Silk, mohair, cashmere and other luxury fibres
Other titles in the Woodhead Publishing Limited series on fibres, published in association with The Textile Institute: Series Editor: Professor J E McIntyre Wool science and technology High-performance fibres Synthetic fibres Cotton science and technology Bast and other leaf fibres Regenerated cellulose fibres
Silk, mohair, cashmere and other luxury fibres Edited by Robert R Franck
Cambridge England
Published by Woodhead Publishing Limited in association with The Textile Institute Woodhead Publishing Ltd Abington Hall, Abington Cambridge CB1 6AH, England www.woodhead-publishing.com Published in North and South America by CRC Press LLC 2000 Corporate Blvd, NW Boca Raton FL 33431, USA First published 2001, Woodhead Publishing Ltd and CRC Press LLC © 2001, Woodhead Publishing Ltd The authors have asserted their moral rights. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts have been made to publish reliable data and information, but the authors and the publishers cannot assume responsibility for the validity of all materials. Neither the authors nor the publishers, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming and recording, or by any information storage or retrieval system, without permission in writing from the publishers. The consent of Woodhead Publishing and CRC Press does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from Woodhead Publishing or CRC Press for such copying. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress. Woodhead Publishing ISBN 1 85573 540 7 CRC Press ISBN 0-8493-1311-2 CRC Press order number: WP1311 Cover design by The ColourStudio Typeset by Best-set Typesetter Ltd., Hong Kong Printed by T J International, Cornwall, England
Contents
Preface Acknowledgements
ix xi
1
Silk ronald currie
1
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13
Introduction and history Silk fibre and its characteristics Silkworm rearing and cocoon production Reeling and yarn production Raw silk testing and classification Yarn and fabric manufacture The care of silk Sand-washed silk The market position of silk Silk production and trade today Silk producing countries Silk consuming countries What about the future? Acknowledgements Bibliography
1 9 11 20 24 28 35 37 39 40 48 55 60 66 67
2
Mohair lawrance hunter and mrs e l hunter
68
2.1 2.2 2.3 2.4 2.5
Introduction and brief history Chemical and physical fibre properties Fibre production and early processing Yarn and fabric manufacture Mohair production in various countries
68 74 88 104 109 v
vi
Contents
2.6
Marketing and cost considerations Acknowledgements References
113 117 117
3
Cashmere, camelhair and other hair fibres j dalton and r franck
133
3.1 Introduction 3.2 Cashmere, Pashmina and Cashgora 3.3 Camelhair 3.4 Alpaca fibre 3.5 Llama fibre 3.6 Vicun˜a fibre 3.7 Guanaco fibre 3.8 Angora 3.9 Yak fibre 3.10 Musk ox fibre References Bibliography
133 136 143 147 152 154 158 162 166 170 173 174
Glossary
175
Appendix 1
International trade rules for raw silk and other products of silk Appendix 2 Spider silk Appendix 3 Composition of mohair fibres and of amino acids Appendix 4 Mohair yarn spinning and properties Appendix 5 Mohair fibre and fabric properties Appendix 6 Mohair dyeing and finishing Appendix 7 Mohair product list Appendix 8 Rules for the use of the Mohair trade mark (label) Appendix 9 Scotland and China and cashmere trade Appendix 10 Quality assessment of goat hair for textile use Appendix 11 Luxury flame retardant fabrics for aircraft applications Index
179 189 191 198 210 213 214 219 220 227 234 243
Contributors
Editor:
Mr R Franck 3 Garden Road Bromley Kent BR1 3LU UK Tel: 0208 402 0307 Fax: 0208 402 0308 e-mail:
[email protected]
Chapter 1 Silk Mr Ronald Currie Former Secretary General International Silk Association 34 rue de la Charité 69002 Lyon France Tel: 0033 478 42 10 79 Fax: 0033 478 37 56 72 e-mail:
[email protected]
Chapter 2 Mohair Dr Lawrance Hunter and Mrs E L Hunter CSIR Division of Manufacturing and Materials Technology PO Box 1124 Port Elizabeth 6000 South Africa Tel: 027 41 5832131 Fax: 027 41 5832325 e-mail:
[email protected] vii
viii
Contributors
Chapter 3 Cashmere, camelhair and other hair fibres Mrs J Dalton The Homestead Farm Bakestonedale Road Pott Shrigley Macclesfield Cheshire SK 10 5RU UK Tel: 0162 5572 381 and Mr R Franck (as above)
Preface
When The Textile Institute and Woodhead Publishing Limited decided to produce a book on luxury textile fibres, we immediately came across the problem of which fibres to include. What makes a fibre luxurious – its softness, its rarity and therefore its price, its ‘image’ (no doubt a consequence of the previous two factors)? If this is so, then why did we not include Sea Island cotton and flax? There was no good reason on the basis of image or for the other reasons mentioned. It really came down to the fact that, in the series of books on various textile fibres of which the present one forms a part, cotton and the other vegetable fibres will each have their own coverage, and we believe that it would be more appropriate to include Sea Island cotton and flax in these. None of the fibres covered in this book are produced in large quantities. Even silk, with an annual production of approximately 70 000 tonnes, is not a major fibre. The total annual production of all the luxury fibres discussed in this book, of the order of 100 000 tonnes, is negligible in comparison with the world’s total textile fibre production of 50 000 000 tonnes. Their production and harvesting are difficult and labour intensive, they often come from remote areas of the world where access and transport are difficult, and their prices are high to very high. Nonetheless, their fineness, softness, warmth and pleasurable handle have secured them a firm place in the niche areas of luxury apparel and furnishing fabrics. Were these fibres to disappear, many thousands of people in developing countries would suffer from a loss of an income which, if small by developed country standards, contributes in an appreciable way to their financial security. As the quantities produced are so limited, the prices of all these luxury fibres can be subject to wide fluctuations. A sudden drop in demand from a major market or a diminution in production for one reason or another can lead to prices increasing or decreasing by 50 % or more in a period of a few weeks. It is striking that certain general basic marketing concepts emerge, and when these are ignored problems arise. One of these basic concepts is to match, as far as is possible, supply and demand. Concerning demand, basic statistical techniques exist which ix
x
Preface
permit the forecasting of demand over a period of two to three years with considerable accuracy and these are used by the synthetic fibre industry and their raw material suppliers as a matter of routine, so why not for silk and luxury hair fibres. Regarding supply, the problem is more difficult because in the case of silk and luxury hair fibres this depends on the number of animals in existence and this cannot be rapidly increased or decreased. However the knowledge of future demand would enable the trade associations concerned to pass on this information to producers who would then, over time, be able to adjust their own activities to suit their individual interests. At the moment all, in this respect, are operating in the dark! Being expensive, the fibres necessarily have a market which is limited to wealthy consumers who buy luxury goods not only for their intrinsic qualities of appearance, softness, warmth, handle and comfort but also simply because they are rare and expensive. It is the sum of such objective and perceived qualities which creates the image of the clothing and furnishing fabrics made from luxury fibres and which persuades the consumer to spend considerable sums of money in their purchase. In this respect, a cashmere garment is the textile equivalent of a Rolls Royce, a diamond necklace or a holiday home in the Caribbean! However, such status carries an inherent risk for goods of this kind because if, for any reason, their image is lowered, perhaps because of a genuine decrease in quality or of over-supply causing a drop in price, their attraction for wealthy consumers will fall and they will spend their disposable dollars elsewhere. Should the damage to the product’s image be serious it may have difficulty in recovering its market, and two examples of events which have damaged a fibre’s image are included in the book. Although difficult to prove direct cause and effect, these two cases (sand washed silk and poor quality cashmere knitwear) probably led to a decrease in consumer acceptance for a few years. In both cases, the poor quality of the product led to its own demise and luckily, the damage done to the reputation of the fibres concerned was not permanent. Whilst it is very difficult for Trade Associations and others concerned to prevent all such occurrences, remedial and preventative measures are possible, from regulatory action to more effective marketing and promotion. However, these require unity of purpose, adequate marketing budgets, and the co-operation of all concerned. These are not always forthcoming. Finally, although spider silk is not a luxury fibre in our general sense of the term, we have included it in this book because very little has been published about it. We do believe that the subject will be of sufficient interest to textile professionals to warrant its inclusion and so provide a wider circulation of information concerning this recent development in textiles. Bob Franck
Acknowledgements
Many have helped by supplying information and advice on the fibres covered in this book. The Editor would particularly like to thank the following for their help and encouragement: Joyce Dalton (Dalton Lucerne), Nan Kern (Cashmere and Camel Hair Manufacturers Association), Don Fox (Forte Cashmere Company) and Francis Rainsford (Internacional de Commercio). The Editor would also like to acknowledge Antonio Canevarolo who provided the photographs for Pier Alvigini’s book, The Fibres Nearest the Sky.
xi
Silk worm
Spider
Silk
Cashmere wool
Mohair
Goat hair
Common goat Bactrian
Camel hair
Dromedary Camel hair
Camel
Hair fibres
Guanaco
Camel family
Llama hair
Llama
Alpaca
Alpaca hair
Llama
Animal and insect producers of luxury fibres (after W Von Bergen).
Cashmere goat
Angora goat
Goat family
Luxury fibres
Vicuña wool
Vicuña
Rabbit hair
Rabbit
1 Silk
1.1
Introduction and history
Silk has a whole series of connotations which transcend its actual technical characteristics. A simple experiment will suffice: say the word ‘silk’ to a woman and ask her what the word conjures up for her. It is likely that she will respond with words like ‘sensuality’, ‘luxury’, ‘glamour’. These qualities may now be available, to a certain extent, among other fibres but it is very unlikely that the mention of nylon, polyester or polypropylene will spark off quite the same set of dream-like reactions. Silk is also the only fibre which has inspired writers and poets over the ages. The very word ‘silk’ has entered everyday language in such phrases as ‘smooth as silk’, ‘silken hair’. It has even gone beyond the realm of textiles, and its name is used to promote goods and services as diverse as cigarettes, shampoo, whisky and airlines. Which indicates that silk is not perceived as an ordinary fibre but one which has come to represent something almost magical. This legendary quality of silk has several explanations: – – – – –
Its geographical origins. The way it is produced. How it was used in the past. Its real technical qualities. Its use in different textile applications.
There is also the fact that silk is a very small fibre in terms of global production quantities. In overall textile fibre production it accounts for less than 0.2 %, as compared with over 51 % for cotton and 40 % for synthetic fibres. As silk production declines and that of man-made fibres increases, this proportion is likely to become even smaller.
1
2
Silk, mohair, cashmere and other luxury fibres
1.1.1 The origins According to Confucius, the discovery of silk goes back to 2640 bc. Legend has it that a Chinese princess, Xi Lin Shi, was drinking tea in a mulberry garden when a cocoon dropped into her cup. The hot tea dissolved the hard outer layer of the cocoon. In trying to extract it with her long fingernail, she discovered that the cocoon contained a continuous filament. As she kept pulling on the thread, it continued to unwind. The princess had just invented the first technique of reeling silk. At that time in China’s history, weaving was already well-established, so it was possible to convert this new-found fibre into fabric. Although it is difficult to prove with certainty, it is highly likely that the discovery of silk went hand-in-hand with some important improvements in the technology of weaving. Recent archaeological discoveries in China, notably in Hubei province in 1982, have brought to light fragments of some highly elaborate fabrics, over 2000 years old, which could only have been produced on sophisticated looms. These fabrics included chiffons, brocades and gauzes and the majority of them were embroidered. If the discovery of silk really did lead to vast improvements in weaving (and in other processes such as dyeing and printing) it is because of another special characteristic of silk, namely that it is the only natural fibre in the form of a continuous filament. All other natural fibres, wool, linen, cotton, cashmere, have to be spun into a yarn from short fibres. (This is also the way in which spun-silk is manufactured, as described later.) Although today a single silk cocoon can yield up to 1600 metres of continuous filament, this is the result of centuries of selection and development of the silkworm, but in ancient times the yield was obviously much lower, possibly between 100 and 150 metres per cocoon. Nevertheless, the continuous nature of the silk thread made it much stronger and easier to weave than cotton, flax or wool. The Chinese were quick to realise the potential of this extraordinary fibre which, in their own expression, ‘came from heaven’. They took every precaution to make sure that the secret of its origin was carefully guarded and made the revelation of its derivation an offence punishable by death. From the very beginning, silk was the object of two major orientations, one technical and the other marketing, which were to mark its development right up to present times. First of all, the Chinese set about domesticating the silkworm, originally an insect which lived in the wild, so as to optimise both the quantity and the quality of the filaments produced. Secondly, the final product, embroidered or printed fabrics and garments, was reserved for an exclusive market. Silk was used by the Empress and her court and as a means of payment for high-ranking civil servants. It was also the means of exchange for products which the Chinese wanted to import. From the
Silk
3
first millennium, China was already exporting silk fabrics to India, central Asia and ultimately Europe. This trade became progressively more organised with the extension, in the first century bc, of the legendary Silk Roads. The Silk Roads, which were to become the first ever major trade route, are generally considered to have their starting point in the city of Ch’Ang’an (known today as Xi’an). They spread westwards into central Asia and India. In addition to the land routes, the maritime routes also made a major contribution to the spread of silk throughout Asia and Arabia.
1.1.2 Silk production outside China Although silk fabrics were exported from China throughout south-east and central Asia, the most important fact for the future of silk was the loss of China’s production monopoly. It was no doubt inevitable that one day the jealously guarded secret of the silkworm would be broken. Silk as we know it is produced by the domesticated silkworm, Bombyx mori, which originated in the wild, but numerous other varieties of wild silkworm existed in various countries, notably India, which is still the world’s major producer of wild silk. The basic idea of a fibre-producing insect was therefore probably familiar to other peoples. Bombyx mori sericulture is thought to have spread to India through Khotan in Chinese Turkestan around 140 bc. Sericulture was introduced to Korea by Chinese immigrants in about 1200 bc and from there it reached Japan. There are several versions of the way in which the Japanese learned how to produce silk. It is likely that military conquest was the reason, for Japan invaded Korea in the third century bc and Korean prisoners, including many silk farmers, were brought to Japan. The history of silk is not merely economic. It has always been intimately connected with the major political and military events of history. The Roman Empire, which in the first century bc extended throughout the Mediterranean basin, attempted to expand eastward from its frontier on the Euphrates. Seven Roman legions under the command of Marcus Licinius Crassus, their lines of communication stretched to the limit, came into conflict with an army composed of Parthian tribesmen near the city of Carrhae (today, Harran in Turkey). The result of the battle was a disastrous defeat for the Roman army and the death of its commander. Apart from the terrible efficiency of the Parthian archers, one of the factors which contributed to the utter demoralisation of the legionaries was the sight and sound of the banners which the Parthians unfurled near the end of the day. These brilliantly coloured and embroidered banners were the first contact the Romans had with silk.
4
Silk, mohair, cashmere and other luxury fibres
From then on, silk was to become a feature of Roman life, either through trade or as the spoils of more successful campaigns beyond the eastern reaches of the Empire. Less than 50 years after the terrible defeat at Carrhae, silk had become so widespread in Rome, not only on ceremonial occasions but among the wealthier citizens for everyday wear, that the Senate had to limit its use to women. Although the official reason was that silk was considered too effeminate for men, the actual grounds were probably economic, because all silk was imported and hence responsible for a considerable outflow of capital. (About 1500 years later, the same reason led to the introduction of silk manufacture in France.) In the early centuries of the Christian era, the main centre of the silk trade outside China was Persia. Weaving and finishing were also known in Syria, Greece and Egypt. The raw material, raw silk, was obtained by importing from China or by recovering silk yarn from imported fabrics. The Emperor Justinian was anxious to gain economic independence in the silk trade by eliminating middlemen as far as possible. In 552 bc, he sent two monks on a mission to the mysterious eastern territories, the land of the Sers. (Sers was the name given to the Chinese at that time and the root ‘ser’ is still found in such words as sericulture and sericin.) The ostensibly evangelical objective of the mission concealed its real purpose, which was to bring back the secret of silk production. The monks, whose knowledge of silk came from their having lived in China, were to be handsomely rewarded if they succeeded, which they duly did. They brought back silkworm eggs hidden in their hollowed-out canes, and this early example of industrial espionage marks the beginning of sericulture in Asia Minor and later in North Africa and Europe. This was by no means the beginning of the end of trade in silk, however, which continued to flourish and was to receive even more impetus after the next major political upheaval, the Arab conquest of Syria and Persia. In the space of barely 100 years, Islam spread as far east as the frontiers of India and China and as far west as Spain. The Arabs not only assimilated the artistic traditions of the vanquished territories, they developed them even further. Their appreciation of the silk fabrics that they found in Syria and Persia led them to create workshops to provide new silk products. Damascus was to become the centre of silk creation under Arab rule. Its importance as a creative centre of weaving technology is reflected in the special type of fabric known as damask. The major centre of textile design and weaving in the Roman Empire, Alexandria, also fell to the Arab invaders and brought them not only advanced techniques in fabric production but also new artistic influences. It was the Islamic conquests along the southern rim of the Mediterranean that led to the introduction of sericulture to North Africa, Sicily and Spain. In Spain, raw silk production started in Murcia and Valencia, while the
Silk
5
industry was to flourish in Almeria, Granada and Cordoba. (It is interesting to note that if Charles Martell had not halted the Moorish invasion of France at Poitiers in 732, sericulture might well have started up in France some 860 years before it actually did.)
1.1.3 The development of silk in Europe At this time, silk was used throughout Asia and the Arab world, but remained relatively rare in Europe. Silk fabrics were appreciated as trophies of war or as gifts from foreign ambassadors but their use was not widespread. One of silk’s essential functions was as a means of exchange; goods could be bought or bartered using silk. Because of its exceptional resistance to the passage of time, silk was considered a solid investment. The spread of the silk industry to Europe really began with the conquest of Sicily by Roger II in 1060. Not only did he foster the existing silk industry established in Palermo, but he also imported Greek and Jewish workers to develop the industry, both from a technical point of view and by the use of designs hitherto unknown in Sicily. The next decisive step in the development of silk in Europe came from the Crusaders, who were in contact with the superb silk creations developed by the Persians, the Arabs and the inhabitants of Byzantium. Silk was no longer reserved for kings and emperors but began to find its way into the homes of wealthy merchants and soldiers. In the early Middle Ages, Italy was composed of a number of flourishing city-states and it was in one of these, Lucca, that the silk industry started, with the help of refugees from the Norman conquest of Sicily. In this unstable period of Italian history, the fortunes of the city-states could change very quickly and Lucca was eventually supplanted by Florence as the chief silkproducing city in Italy. Florence already had a woollen industry and was thus able easily to assimilate silk weaving. Although the merchants of Lucca remained, many of the weavers moved to Florence, Bologna, Genoa and Venice. During the twelfth and thirteenth centuries, the overland route used for silk trading with China had been closed by the Arabs, and commerce became highly unreliable or was diverted to the maritime silk routes. Once again, political events were to change the picture, not only in terms of trade but in terms of artistic influence. The conquest of central Asia by the Mongols pacified the territories crossed by the overland silk routes and trade between east and west underwent considerable development, not only in silk but in a vast range of goods such as gold and silver, porcelain, spices and horses in both directions. Italian art was at that point undergoing its most creative period, and the influx of Chinese and central Asian designs profoundly influenced the Italian artists of that time. Marco Polo’s travels
6
Silk, mohair, cashmere and other luxury fibres
in China, at the end of the thirteenth century, also gave new sources of inspiration to the silk weavers in Italy, in particular to those in his native city, Venice. Florence and Venice continued to vie for creative supremacy, especially in the field of velvets. The industry was well organised, under the aegis of the guilds and corporations, and already there were regulations governing what is known today as intellectual property. It was not until the fifteenth century that silk manufacture really began to develop in France. Although there were silk weavers in Avignon, working to provide vestments and embroideries for the exiled Pope and his entourage, France was essentially involved in the trade of silk products but not yet their manufacture. The chief centre of this trade was Lyon, which was later to become the centre of the whole European silk industry. The starting point for trade in silk was the existence of two annual tradefairs established in Lyon by Charles VII in 1419. These fairs attracted merchants and bankers from Florence whose influence on the city of Lyon can still be seen today. The old quarter of Lyon is characterised by Florentine architecture. The Italians not only developed the silk trade but were also dressed in silk garments and thus served as a kind of walking advertisement for their wares. At the same time they proved that silk could be worn not only by kings and aristocrats. The purchase of foreign silks began to represent a serious drain on the country’s foreign exchange, to such an extent that Louis XI decided to initiate silk manufacture in France. Lyon’s proximity to Italy and the presence of numerous Florentine bankers and merchants who lived there made it the ideal place to establish silk weaving. However, Louis XI’s offer (1466) to grant Lyon the privilege of being the first centre of silk manufacture in France met with a very cool reaction from the Lyon Chamber of Commerce (or Consulat as it then was). Either the Lyonnais were afraid of spoiling their relationship with the Italians or more prosaically they were unwilling to pay the money the king was asking for the privilege. The most plausible explanation is that the Lyon silk merchants, influential members of the Consulat, were making so much money from importing Italian silks that they were loath to contribute to the creation of local competition. Whatever the reason, Louis XI tired of insisting and set up the first official manufacture of silk in Tours in 1470, followed by another in Nîmes, intended to compete with Avignon. Tours became an important centre of silk weaving, not only of fabrics for garments but chiefly for furnishing fabrics to embellish the châteaux along the Loire. During this time, there were a few Italian weavers, from Piedmont and Genoa, working on a small scale in Lyon. The most enterprising of these immigrants was Etienne Turquet, a Piedmontese trader and weaver.Turquet was quick to see the possibilities of creating a silk industry in his adopted
Silk
7
city, especially as one of the major producing areas, Genoa, was going through a period of political turmoil. Together with the city authorities, he obtained from the then king, François I, in September 1536, letters patent which gave the city of Lyon the right to establish a silk industry and also, what was even more important, the monopoly of raw silk imports. The king had no difficulty in acceding to the requests of the people of Lyon because he had always held the city in the highest esteem, and had even considered making it his capital. By this decision he was able to stem the outflow of currency and contribute to the downfall of a major competitor, Genoa. In order to hasten the development of the nascent silk industry, François I also decreed a certain number of privileges for silk workers, including tax exemptions, as a means of attracting foreign (i.e. Italian) craftsmen to Lyon. The skilled workers already installed in Nîmes and Tours moved to Lyon to benefit from these advantages, thus beginning the decline of the industry in the towns they left and the concentration of silk manufacture in Lyon. There was no lack of venture capital from the Florentine bankers already well acquainted with Lyon through its trade fairs. For the time being, Lyon depended on imports of raw silk from Italy to supply its manufacturing industries. The next logical step in ensuring the industry’s economic independence was to start silk production in France. Sericulture started up in the Rhône valley under Henri IV. The architect of this production was the agronomist Olivier de Serres and the initial purchases of mulberry saplings and silkworm eggs were financed by a special tax raised in Lyon, following a decree published by Henri IV in 1604. From then on, Lyon was able to become less dependent on imports of foreign raw silk, but it was not until the middle of the nineteenth century that French production was able to make a really significant contribution to the industry’s needs in terms of raw silk. The Ottoman Empire was also a major centre of silk production and manufacture at this time, concentrated in the town of Bursa, where some silk production continues to this day. The Italian industry was also still extremely active, with Florence now the dominant force, but political and economic unrest hampered the progress of the Italian silk weavers and enabled Lyon to begin to position itself on the international market for silk fabrics. The relative peace that France enjoyed, at least after the end of the wars of religion, enabled the industry to prosper while the city-states of Italy were in almost permanent conflict with each other. One of the strong points of the Lyonnais silk workers was their capacity to innovate, sometimes by improving on existing machinery. The draw-loom perfected in Lyon from an Italian design enabled the weavers to execute larger and more complicated patterns. Throughout the seventeenth century Lyon continued to develop its weaving, but in 1685 the revocation of the Edict of Nantes, which for a
8
Silk, mohair, cashmere and other luxury fibres
hundred years had protected the Huguenots from religious and political persecution, dealt a serious blow to the silk industry. Huguenot refugees exported their technical skills and business acumen to other, more tolerant, European countries. The Netherlands, Germany, Switzerland and England were therefore able to benefit from the misfortunes of the Protestant silk workers and traders and create their own silk industries. In London, the silk industry was concentrated in Spitalfields. The courts of Europe were the greatest patrons of the European silk industries in the eighteenth century. Catherine the Great of Russia, among others, placed orders for silk fabrics from the well-known designers of the time. The new designs being produced in France by such famous artists as Philippe de la Salle represented a break with the past. They were more figurative and less symmetrical than in the previous century. They were also more refined, while the constant development of weaving techniques made them more and more intricate. Although it is not often realised, blended fabrics including silk were also commonly produced at this time. The silk manufacturers understood even then that they had to offer more than just the most luxurious fabrics if they were to reach a wider market. In the nineteenth century, Lyon had established its leadership in luxurious furnishing fabrics. A major step forward came with the invention by Joseph-Marie Jacquard of the mechanism which bears his name. The idea of selecting individual yarns to compose the designs of a figured fabric was not new, but until Jacquard’s invention it was done by hand. The ‘draw-boy’ (as a boy, Jacquard himself was one) pulled the cords which controlled the warp-yarns at each pick of the loom. Jacquard’s process consisted of translating the required design onto a perforated card placed in a mechanism above the loom which replaced the draw-boy and also made the weaving quicker and more efficient. This enabled the Lyonnais to gain a technical advantage over their European competitors and produce fabrics appealing to a wider clientele. Nowadays, Jacquard designs are no longer realised through perforated cards but by computer, which is a very neat completion of a logical cycle. Jacquard is sometimes considered as the father of computer language, since the perforated-card system is an early example of binary language; there is a hole or there is no hole. Although Lyon was to establish its advantage over its competitors, particularly the Italians, the nineteenth century also saw the decline of silk production in France. The first major event was an outbreak of a disease endemic to the silkworm, pébrine, which decimated production in the Rhône valley in the middle of the century. Although a young scientist then at the beginning of his career, Louis Pasteur, discovered the causes of this deadly disease and devised means of combating it, the epidemic was the start of the slow decline of French sericulture. Despite a revival of produc-
Silk
9
tion in the years 1865–1870, the French silk industry began to look for its raw material supplies elsewhere. Commercial exchanges with China and Japan were beginning to develop and the opening of the Suez Canal in 1872 meant that Asian raw silk could be shipped direct to Marseilles, instead of going through London. London was a major centre of the raw silk trade because of the superiority of Britain’s shipping, built on the experience of trade in tea and other commodities from Asia and the efficiency of the clipper ships. In the United Kingdom at this time, the silk manufacturing centre was Macclesfield. However, the British silk industry benefited from protectionist trade measures which were abolished in the context of the free trade movement which gained strength in England in the 1860s. Foreign, mainly French, silks were able to enter the UK much more freely, and this obliged many of the Macclesfield weavers to emigrate, in particular to Paterson, New Jersey. Macclesfield nevertheless continued to be a centre of quality silk production but on a smaller scale. In the latter part of the nineteenth century there were still 60 000 looms in Great Britain but strong competition for the British silk industry also came from Krefeld in Germany (with 70 000 looms) and Zürich, which counted over 30 000.
1.2
Silk fibre and its characteristics
As mentioned before, silk is a natural fibre, in common with others such as cotton, wool, linen, cashmere and mohair. Silk is a protein fibre and its amino acid composition is close to that of the human skin. The proteins composing the outer layer of sericin are soluble in hot water while the proteins in the fibre itself are insoluble. When pure, silk fibre is hygienic and non-allergenic, but the various treatments to which it is subjected during its processing may introduce elements that can cause irritation of the skin. Compared with the other natural fibres, silk has certain specific characteristics which set it apart. These specific properties of silk are summarised in Table 1.1. Table 1.1 Some properties of silk Physical properties
Mechanical properties
Moisture regain: 11 % Shrinkage (wet): 0.9 % Specific gravity: 1.3
Tenacity: 5 gr/denier Elongation: 17 %–25 % (dry), 30 % (wet) Rigidity modulus: 2.5
10
Silk, mohair, cashmere and other luxury fibres
These physical characteristics are determined by the structure of the macromolecule composing the fibroin as shown in Fig. 1.1. Part of the macromolecule is made up of amino acids with a low molecular weight, offering a series of crystalline regions which confer a high degree of tenacity on the fibre. The rest of the macromolecule is characterised by the presence of amorphous areas enclosing amino acids of a relatively higher molecular weight. The presence of both crystalline and amorphous zones makes for a combination of strength, flexibility and elasticity.
1.1 Silk micrograph (ITF).
Silk is composed of two protein groups, forming respectively the fibroin and the sericin. In the fibroin, alanine and glycine together account for 70 % of the total composition, whereas in the sericin they make up about 15 %. The chief component of sericin is another amino acid, serine (30 % of the total). –
–
Silk is the only natural fibre which exists as a continuous filament. Each Bombyx mori cocoon can yield up to 1600 metres of filament. These can be easily joined together using the adhesive qualities of sericin to form a theoretically endless filament. The silk fibre’s triangular cross-section gives it excellent light reflection capability.
Silk – –
– –
11
The silk fibre is smooth, unlike those of wool, cotton and others. This is one of the reasons why silk fabrics are so lustrous and soft. Silk can absorb up to 30 % of its weight in moisture without creating a damp feeling. When moisture is absorbed it generates ‘wetting-heat’ which helps to explain why silk is comfortable to wear next to the skin. Silk has a tenacity of approximately 4.8 grammes per denier, slightly less than that of nylon. Silk has poor resistance to ultraviolet light and for this reason is only recommended for those curtains that are lined or not exposed to direct sunlight.
From the nineteenth century, attempts have been made to reproduce the qualities of natural silk. It is no coincidence that rayon was initially known as ‘artificial silk’ before the term was banned. The basic principle of the production of synthetic fibres is the extrusion of a semi-liquid mix through a tiny hole to form a filament that hardens on contact with the air, and this is exactly the same principle that is used by the silkworm. Although the chemical composition of natural silk is extremely wellknown and the ‘recipe’ can be reproduced, no one has so far succeeded in spinning a continuous filament of natural silk. This is because the molecular organisation of the sericin-plus-fibroin combination is not the same when it is in the body of the silkworm and when it is extruded. For the time being, only Bombyx mori knows how to rearrange the molecules into a continuous fibre. Obviously, chemical fibres have made and continue to make enormous progress. They often possess characteristics which are far superior to those of silk, particularly in the field of washing and ironing. They even, in some cases, have the appearance and the feel of silk. However, not one of the new fibres, for all their undoubted qualities, has so far succeeded in bringing together all the characteristics associated with silk, and in particular its specific combination of handle, drape, appearance, lustre and comfort when worn. One of the greatest tributes to silk is the number of brand names and advertisements for synthetic fibres which describe them by using such adjectives as ‘silky’ and ‘silk-like’.
1.3
Silkworm rearing and cocoon production
Figure 1.2 shows the flow chart for silk manufacturing. There are hundreds of varieties of Lepidoptera which produce silk in the wild. The silk thread presents extraordinary properties of physical strength and insulation, hence its use in building prey-catching structures or protective ‘housing’.
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Silk, mohair, cashmere and other luxury fibres China Cocoons
Reeling Raw silk
Throwing Thrown silk yarns
Weaving Knitting Warp-and-weft fabrics Knitted fabrics
Silk waste De-gumming Carding Combing Spinning Spun silk yarns Silk noil yarns Yarn-dyeing
Sewing and embroidery threads Jacquard weaving
De-gumming Dyeing Printing Finishing Finished fabrics
Making-up Garments Accessories
Retail
1.2 Silk manufacturing flow chart.
Over the centuries, one of these species, Bombyx mori, has been progressively domesticated to fulfil its two most important functions and nothing else, namely to produce a textile fibre and to perpetuate the race. Today, Bombyx mori is the only totally domesticated animal, that is to say it is entirely dependent on man for its survival, unlike other ‘domestic’ animals, cats or dogs for example, which could survive if abandoned to their own devices.
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This domestication has taken the form of suppressing the silkworm moth’s ability to fly, so that it is entirely captive. This means that its production of eggs can be totally controlled. The moth has no digestive tube, so after mating and laying its eggs it dies. It is also sightless. Bombyx mori (literally ‘mulberry silkworm’) is so named because mulberry leaves are its only food. Here we have one of the first and most important constraints on sericulture, namely there must be an accessible and abundant supply of mulberry leaves to feed the silkworms. Hence, sericulture is confined to areas where such factors as temperature, hygrometry and soil conditions are favourable to mulberry cultivation. In the past, this meant that sericulture was concentrated in temperatezone countries, where the white mulberry, Morus alba, was well-established. Southern Europe, the Mediterranean basin, central Asia, northern India, China, Korea and Japan were ideal places for sericulture for this reason. The mulberry is a very hardy tree and can adapt to many different climates. Some varieties have been developed which can thrive in subtropical conditions, which means that silkworms can be fed practically throughout the year. In temperate areas, however, the mulberry tree only yields leaves twice a year, in May and September. Since the silkworm will eat nothing else, it is leaf production which determines when the worms can be reared. Silkworm eggs can be stored until they need to be hatched, but there is no point in hatching them if there is no food available. Consequently, in economic terms, farmers in temperate zones cannot live on silkworm rearing (and therefore cocoon production) all the year round. This is one of the reasons which resulted in the decline and eventual disappearance of sericulture in France, Italy, Spain and Portugal, as well as in Korea. In other countries, for example in Colombia, continuous cocoon production is possible because the climatic conditions allow for year-round leaf production. In Japan, Italy and France attempts are being made to replace mulberry leaves as the sole food of the silkworm. An artificial diet, containing some mulberry-leaf powder but also protein from other sources, such as soy, is being developed. Although this type of feeding is not yet viable on an industrial scale, except in Japan, and is consequently expensive, it offers a hope of solving two major problems: the need to wait for propitious periods of the year to hatch the silkworm eggs and, secondly, the need to rear silkworms in close proximity to the mulberry plantations. The silkworm is not only very fussy about its source of food, but the leaves also have to be perfectly fresh. Despite attempts to dehydrate or freeze-dry mulberry leaves, the silkworm will only recognise the real thing. The silkworm begins its existence as a tiny egg, the size of a pin-head. In just over one month, the egg will develop into a fully grown silkworm. In this respect Bombyx mori can lay claim to another record, namely the
14
Silk, mohair, cashmere and other luxury fibres
fastest rate of growth in the animal world. From the egg to the adult caterpillar, the weight is multiplied 10 000 times. Silkworm eggs are prepared in grainage stations, which select the appropriate eggs for the area and the season in which they are to be used. The eggs are usually delivered in boxes of 20 000 (or 33 000 in some countries). Once the rearing season can begin, i.e. when the temperature is right and there are enough mulberry leaves, the eggs are put into incubation at 25 °C and the young silkworms hatch roughly 12–14 days later. The newly hatched worms immediately start looking for something to eat and at the beginning of their growth have to be fed at regular intervals with tender young mulberry leaves. During the feeding period, eating is the silkworm’s preoccupation. Its appetite is voracious and it has to be constantly looked after. Not only is it a very finicky eater, but it requires specific rearing conditions which have been described in sericultural manuals ever since ancient Chinese times: no noise (such as a dog’s barking), no odours (the minders should not eat garlic), harmonious development of all the worms simultaneously (malingerers should be eliminated and fed to the fishes) and so forth. The growth of the silkworm is spread over five ages or ‘instars’, and is so rapid that the worm quickly outgrows its skin and has to stop eating four times during its lifetime in order to shed its skin and then resume its feasting. Each age is separated from the next by this period of moulting. The instars are of unequal duration: first instar 3–4 days; second 2–3 days; third 3–4 days; fourth 5–6 days; fifth 7–8 days. (These periods include moulting.) In Fig. 1.3 the feeding of fourth age silkworms is shown. Silkworm rearing therefore requires an abundant and accessible supply of fresh mulberry leaves as well as a large number of individuals to pick the leaves, chop them into a manageable size, feed the silkworms, clean out their litter and so on. The rearing houses must be kept meticulously clean and disinfected regularly in the interval between rearings. Figure 1.4 shows the rearing mat being cleaned. The labour intensive nature of sericulture is one of the causes that led to its decline and ultimate disappearance in Europe. The future of sericulture is in countries which have, apart from the right climate, an abundant source of inexpensive labour. Even then, cocoon production will most often be an addition to the farmer’s revenue rather than its mainstay. Once the silkworm has reached the limit of its adult development, it stops eating and prepares to spin its cocoon. The cocoon is a shelter designed to protect the silkworm from predators while it metamorphoses into a chrysalis, the intermediate stage between the larva and the moth. To build its cocoon the silkworm extrudes the semi-liquid silk contained in its two silk glands which are disposed in a zigzag manner throughout the length of its body, and are therefore much longer than the silkworm itself. They
Silk
1.3 Feeding fourth age silkworms.
1.4 Cleaning out the rearing mat.
15
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Silk, mohair, cashmere and other luxury fibres
1.5 Preparing silkworms for cocooning.
contain a large amount of silk, of which the worm actually ‘empties’ itself through spinning its cocoon, and this is why people often ask how such a large worm can ‘fit into’ such a small cocoon. Figure 1.5 shows the silkworms being prepared for cocooning. Each silk gland produces one strand and the two strands are bound together by the sericin as they leave the silkworm’s body through the tiny hole in its lower lip, the spinneret. The function of sericin is to stiffen the two filaments and protect them from damage, in the same way that the plastic covering of an electric cable protects the copper wire inside. The worm begins by fixing a few individual filaments to a support in order to anchor its cocoon. Traditionally, the support used for this was a sprig of heather, but in modern times racks of small cardboard compartments are used, or sometimes a plastic ‘hedgehog’. In Fig. 1.6 the traditional Japanese cocooning frame is shown. Once the initial strands have been put in place, the silkworm can begin the construction of its cocoon. The sericin-plus-fibroin hardens on contact with air so the resulting cocoon offers good protection and at the same time remains porous which enables its occupant to breathe. The silkworm will take three or four days to complete its cocoon by rotating its head in a rough figure-of-eight movement to enclose its body completely. Inside its cocoon, the larva will change into a chrysalis, which will take about three
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1.6 Traditional Japanese cocooning frame.
or four days. Another ten days later, the chrysalis will in turn change into a moth that will emerge from the cocoon by dissolving the gum which binds the filaments together. Should the cocoon be damaged in this way by the emergence of the moth the silk filaments will be damaged and cannot be reeled. Figure 1.7 shows the harvesting of fresh cocoons. The development of the chrysalis into a moth is therefore interrupted. The cocoons are ‘stifled’, i.e. they are subjected to hot air which kills the chrysalis and so ensures that the cocoon remains intact. There are different stifling methods. The one which takes the longest time consists of stifling at a steady temperature of 110 °C over a period of about 8 hours. Another method consists of stifling at different temperatures, starting at 110 °C, for short periods. The stifling process is followed by drying in a drying chamber, so as to remove the high moisture content of the fresh cocoons and enable them to be stored until they are required for reeling. A certain percentage of cocoons are allowed to reach the end of their cycle, i.e. the emergence of the moth, for reproduction purposes. As soon as they hatch, the moths begin to mate. As they are blind, they are attracted to each other by the female’s powerful pheromones. A male is capable of mating with several females. Mating generally lasts 3 days, at the end of which the female lays between 350 and 500 eggs and then dies. Figure 1.8 shows the female laying eggs.
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Silk, mohair, cashmere and other luxury fibres
1.7 Harvesting fresh cocoons.
1.8 Egg laying.
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1.9 Silk moths being crushed to test for pébrine.
Tests are carried out at this point to detect the presence in the moths of any of the diseases which affect the silkworm. The deadliest of these diseases, pébrine, is highly contagious and can wipe out a whole rearing, hence the need to ensure disease-free layings. Once it has been determined that no diseases are present, the eggs are put into hibernation at a low temperature until they can be hatched at the next rearing season. Figure 1.9 shows silk moths being crushed to test for pébrine. The selection, conservation and cross-breeding of the eggs is the work of grainage stations. It is important to select and to develop silkworm strains adapted to different conditions of climate, humidity and so forth. There are basically two main ‘families’ of silkworms, bivoltine and multivoltine, that have their specific characteristics. Bivoltine silkworms are capable of two generations per year, while multivoltine strains can produce several. These two main groups have different properties that can be defined as follows: Bivoltine strains: – – –
Produce large quantities of thread per cocoon, up to 1600 metres or more. Produce thread of good quality, even, lustrous and strong. Are highly vulnerable to disease.
20 – –
Silk, mohair, cashmere and other luxury fibres Require very strict rearing conditions in terms of hygiene and temperature- and humidity-control. Are much better suited to temperate than to sub-tropical or tropical climates.
Multivoltine strains: – – – – –
Are very hardy and resistant to disease. Will accept imperfect rearing conditions. Are well-suited to sub-tropical and tropical climates. Produce relatively low quantities (400–800 metres per cocoon). Produce a thread of fairly poor quality in terms of physical characteristics.
The obvious answer to overcoming the disadvantages and combining the advantages of the two main branches of silkworm strains lies in crossbreeding, and this is carried out regularly in the silk-producing countries. The best example is shown by India, where sericulture is practised mainly in the south of the country, in the Bangalore/Mysore region. The climate and the rearing conditions are not propitious to bivoltine strains but crossbreeds are frequently used to attempt to produce more and better qualities of raw silk. The main difficulty at present is that the genome of the silkworm is not yet fully known, so the attempts to combine the best characteristics of the two strains are not very certain. However, this situation is due to change in the very near future. Genetic research is developing rapidly and, as is discussed later, a scientific breakthrough was achieved in January 2000 that now makes transgenesis of the silkworm a practical reality. This means that once the Bombyx mori genome has been fully plotted it will be possible to endow the bivoltine silkworm with the best qualities of its multivoltine cousin, to make it less vulnerable to disease, for example, and at the same time make the tough multivoltine varieties produce larger and better qualities of raw silk filament.
1.4
Reeling and yarn production
Before the cocoons are dried, they are carefully sorted to eliminate those which are unfit for reeling because they are stained, deformed, double or otherwise inadequate. These cocoons are not totally discarded and can be used at least partly for producing silk waste, used for the production of spun-silk yarns, and subsequently for some by-products. In some Asian countries the chrysalis is sold to restaurants as a delicacy. The first operation in the reeling process consists of softening the gum (sericin) which binds the thread together because the cocoons are at this stage too dry and too hard to reel. This operation, known as ‘cooking’, con-
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sists of passing the dry cocoons through a series of wet processes designed to soften the sericin bond. The sericin is not removed at this point because its protective qualities are needed throughout the initial industrial processes of throwing and weaving. Reeling, like every other operation in the silk process, was once done entirely by hand and in some countries still is. In Thailand, a major part of raw silk production is hand-reeled, and this gives Thai silk its coarse, irregular and rustic appearance and feel, which are so highly prized by the market. In India, part of the cocoon production is reeled on simple domestic reeling machines known as charkha or on improved versions called cottage-basins. The yarn produced by these simple devices is well-suited to handloom weaving, which remains the mainstay of Indian fabric production. However, if raw silk yarn is required for processing on sophisticated, high-speed textile machines, the necessary quality can only be obtained through using very good multi-end or automatic reeling machines. The ‘cooked’ cocoons are brushed with a stiff rotating brush to find the end of the continuous filament which forms the cocoon. During this process a certain amount of silk waste is produced and set aside for future use in spinning. (Note that in English ‘reeling’ is used for the production of continuous filament, and ‘spinning’ for the processing of short fibres.) Reeling is a critical operation in achieving good quality silk yarn. One of the chief characteristics of a good quality yarn, of any fibre, is its evenness. However, since silk is a natural and not a synthetic fibre a certain degree of irregularity of diameter is inevitable. Thus, the natural unevenness of a silk filament can be attenuated by the quality of the reeling, in which the filaments of several cocoons are combined into one yarn. The filaments from the cocoons are reeled together using the adhesive properties of the sericin to bind them together. As the filaments are fed through a yarn guide on the reeling machine they cross each other in a phase known as croisure (traverse). The croisure (shown in Fig. 1.10) squeezes out the excess water and gives the filaments a very slight twist to ensure their cohesion. The single filament of one cocoon weighs about 2 deniers. (The silk trade continues to use the denier as a system of weight, one denier being the weight in grams of 9000 metres of yarn.) Consequently, in order to achieve the thickness (denier) of yarn required, several cocoons are reeled together. This quality of a silk yarn depends, in the case of semi-automatic reeling, on the skill of the reeler. Seven, eight or ten cocoons are being reeled together to produce a yarn of 13/15, 17/19 or 20/22 denier. Obviously, each cocoon does not contain exactly the same length of filament as the others, so the reeler has to be constantly alert to finding a cocoon which is exhausted, injecting a new cocoon into the basin and joining it up with the others so as to maintain the same diameter of yarn. If the reeler is not vigilant enough, the diameter of the yarn will go, for instance, from eight
22
Silk, mohair, cashmere and other luxury fibres Yarn-guide Skein
Yarn-distributor Pulleys
Swift
Croisure
Yarn-guide
Cocoons
1.10 Croisure.
filaments to seven or six and then back to eight, thus creating an irregular yarn which will cause problems at later stages of processing, particularly during weaving. Today, raw silk is often reeled on automatic reeling machines that have been developed, particularly in Japan, to improve the quality of raw silk and at the same time save on labour costs. A set of electronic sensors permanently measures the diameter of the yarn and detects any variations. As soon as one cocoon is exhausted, the machine will automatically stop the reeling in that particular basin and inject a new cocoon and then resume the reeling process so as to maintain the evenness of the yarn. Although an operative is still necessary to join up the new filament, one operative can look after several basins at a time, thus making for a considerable saving in labour.
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During the reeling process, the silk is reeled first of all onto small reels then re-reeled onto larger reels. This double operation is designed to enable the yarn to dry and to avoid the formation of gum spots, where the sericin has accumulated on the still wet yarn. After re-reeling, the raw silk is packaged into hanks, or skeins as they are called in the silk industry. The skeins are twisted into their characteristic torsaded shape and made up into bales of 60 kilogrammes.
1.4.1 Dupion Mention must be made at this point of another type of reeling. While the silkworms are spinning their cocoons, it sometimes happens that two worms are so close to each other that they spin a double cocoon instead of two separate ones. These double cocoons cannot be reeled in the conventional way but have to be processed on a special machine. This is known as dupion (douppion) reeling, dupion literally meaning ‘double’. The two filaments thus produced are intermingled, and when added to normal filaments in fabric manufacturing produce irregular slubs which create an effect very much in demand for making special fabrics, particularly for bridal wear. These fabrics are often mistakenly known as ‘wild silk’, because they appear natural and irregular.
1.4.2 Wild silk In addition to silk produced by the domesticated Bombyx mori, there are several varieties of wild silk that are produced by totally different insects. Wild silk comes from insects that live in wild or semi-domesticated conditions, notably in India, China and Vietnam. The largest group of wild silk producing insects belongs to the Antheraea family and the silk they produce is variously known as tasar, tussah or tussore. These insects feed on oak leaves, not mulberry, in areas such as the foothills of the Himalaya where small oak trees grow in abundance. Although tasar cocoons contain some continuous filament, it is very difficult to extract and most wild silk thread is used for spinning rather than reeling.Tasar silk is widely used for women’s and men’s clothing and furnishing fabrics. In China, the chief wild silk producing area is in the north-east of the country, in Liaoning province in particular. India is also the home of two other wild silk varieties, muga and eri. Muga is a gold-coloured discontinuous fibre while eri comes from a variety of silkworm that feeds on castor leaves. Wild silk production is very small compared with that of cultivated silk. World raw silk production (Bombyx mori) was around 70 000 tonnes in 1999, while known wild silk production was about 3000 tonnes.
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Silk, mohair, cashmere and other luxury fibres
1.4.3 Spun silk and noil During the initial stages of silk processing, particularly during reeling but also at later stages, a certain quantity of waste silk is produced. This is composed of short fibres as opposed to the continuous filament known as raw silk. Waste silk is also derived from unreelable cocoons, i.e. those discarded during the pre-drying sorting. Pierced cocoons are a major source of waste silk. The term ‘waste silk’ is something of a misnomer because it suggests a product of inferior quality barely worth commercialising. In fact, waste silk is a quality raw material that is processed into two by-products, spun silk and silk noil, both highly valued by the processing industries. It occasionally happens that when there is a shortage of waste silk its price can actually be higher than that of raw silk. While the term ‘schappe’ is commonly used with reference to spun silk in general, the expression was originally used to designate waste silk that had been degummed using the natural fermentation method, in which the bacteria present in the silk waste are allowed to ferment in a warm, humid atmosphere and begin to break up the sericin present on the fibre. This facilitates the subsequent washing and rinsing of the waste. The washing agents used are based on olive oil soap and other alkaline agents such as sodium carbonate. This is particularly important for the silk waste produced from the discarded cocoons, to make sure it contains no foreign matter such as fragments of pupa and cocoon-shell. In addition, pupa residues present in the waste will add to the total amount of fatty acids. The silk waste is then processed in a way which is similar to the processes used for wool and other staple fibres. The silk waste is carded, combed and spun into yarns. These are then singed (‘purged’) to remove hairiness. This yarn can be dyed and made into sewing and embroidery threads or used for weaving. Fabrics woven from silk spun yarns have their own particular appearance, handle and drape and produce very attractive apparel and furnishing fabrics. Alternatively, the short fibres can be blended with other natural fibres such as cotton, wool and linen which have staple fibres of approximately the same length, to give a range of blended fabrics offering various properties such as warmth (silk-and-wool) or coolness (silk-andlinen). During the carding and combing silk waste prior to spinning some even shorter fibres, noils, are produced.
1.5
Raw silk testing and classification
Before raw silk is traded it has to be tested and classified. Testing has two purposes: (a) to determine the characteristics of each lot (usually 600 kg) of
Silk
25
silk and decide for what end-uses it can be employed, and (b) to classify the silk into different grades and thus determine its price. Raw silk is classified according to an international system drawn up by the International Silk Association (ISA) in the years following the Second World War. Representatives of the main producer and consumer countries formed a ‘Classification Committee’ and agreed on the international system which is the world-wide standard, although some minor differences may exist in certain national classification systems. There are 11 grades in the international system of classification, ranging from 6A (the top) through 5A, 4A down to F. These grades apply to raw silks of three different categories: 18 deniers and below, 19–33 deniers and 34 deniers and above. In countries where high-speed machinery is used in twisting and weaving, the minimum grade required is 3A. The grade of the silk is determined after the silk has been subjected to a series of tests. These tests include those for such criteria as evenness, cleanness, neatness, tenacity, winding, size-deviation (average and maximum), elongation, breaking strength and cohesion. There are also some more subjective criteria such as lustre, handling and colour that must be determined. These tests are carried out on small skeins of silk, known as sizing skeins, drawn from the lot of raw silk to be tested. The scope of each of the tests, i.e. what they are aimed at testing, can be summarised as shown in Table 1.2. Raw silk testing is still carried out using a visual system based on an apparatus called the seriplane; this presents a number of standard panels for each of the major criteria. For example, when testing neatness, the operator posts a standard photographic panel for neatness. He then draws samples of the raw silk under test and winds them onto a black panel which is placed below the standard photograph. He then compares the samples against the standard and reaches a judgement on this criterion, for example 95 % neatness. Figure 1.11 shows the testing of raw silk with the aid of a seriplane and Fig. 1.12 demonstrates testing raw silk for cohesion with a Duplan tester. The ‘scores’ obtained for each of the major tests are gathered together to reach the classification. A poor result in one of the tests is enough to declassify the lot of raw silk. However, what counts for the user is the final purpose for which he or she wants the raw silk. If a particular lot has obtained a low mark in evenness, this may not be disqualifying if the silk is intended for doubling and twisting using a large number of ends, where the relatively poor evenness will be less critical than for an application in chiffon, for example, which requires only two ends with a low twist. It is for this reason that it is not enough for the throwster and weaver to know the grade resulting from the different test results. The raw silk merchant, skilled in interpreting the test certificate, advises the industrial user on the possi-
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Silk, mohair, cashmere and other luxury fibres
Table 1.2 Quality control testing of silk skeins Test
Result
Winding test
The number of breaks in raw silk threads over a certain period of winding. The degree of size deviation within the test pieces of sizing skeins. The maximum amount of deviation from the average size. The average size of the silk thread at conditioned weight. The degree and frequency of size variations in silk threads over approximately the same length as the sizing skeins. The type and number of cleanness defects. These defects are categorised as super major defects, major defects and minor defects. ‘Major’ defects include: waste filaments, large slugs (thick places), long knots, corkscrews and loops. The percentage of neatness of raw silk. Neatness defects are smaller than minor cleanness defects and include: nibs (small thick places), loops, hairiness and fuzziness, raw knots (less than 3 mm), fine corkscrews. The tenacity of a 20/22 denier raw silk is 4–5 gr/denier. The elongation of the same raw silk is 18 %. The tenacity (strength) of the raw silk per denier and the amount of stretch up to breaking point. The degree of agglutination of the cocoon filaments making up the silk thread.
Size-deviation test Maximum deviation test Average size test Evenness variation test
Cleanness test
Neatness test
Tenacity and elongation
Cohesion test
ble applications of each lot. Given the relatively subjective and oldfashioned nature of the seriplane method of raw silk testing, there is increasing demand for a new testing method based on electronic systems. In recent congresses of the International Silk Association, testing institutes in Switzerland and Japan have proposed modern alternatives to the seriplane system. If one of these systems were to be officially adopted by ISA, this would probably lead to the drawing up of a new classification system with a reduced number of grades. However, at the present moment no consensus has been reached among producers and consumers on the adoption of a new electronic testing method. Every lot of raw silk which is exported must be accompanied by an official test certificate issued by the competent testing authority in each country. (In China the body responsible for these tests is the China Commodities Inspection Bureau or CCIB.) The test certificate accompanies the
Silk
1.11 Testing raw silk with the aid of a seriplane.
1.12 Testing raw silk for cohesion with a Duplan tester.
27
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Silk, mohair, cashmere and other luxury fibres
shipment of the raw silk and is used as the basis for the price. In a very general way, the price difference between two grades, between say 4A and 5A, is roughly US$1 per kg. This can make a considerable difference in an order of 10 tonnes. On arrival in the importing country, buyers can have the raw silk retested by a local testing laboratory if they have any doubts about the reliability of the test certificate or if their first use of the raw silk has been unsatisfactory. In Japan it is common for all imported raw silk to be systematically retested. In addition to international standards for raw silk classification, the International Silk Association also publishes trade rules for international trade in raw silk and other silk products. These rules form a basis for transactions between sellers and buyers and although they do not have force of law they have the merit of providing a mutually recognisable framework for international trade in silk. (These International Trade Rules for Raw Silk are reproduced in Appendix 1.)
1.6
Yarn and fabric manufacture
Silk is traded in many different forms and at various stages of finishing. From the point of view of the processing countries in Europe, the traditional stages are: – – – – –
Raw silk imported from China or Brazil. Throwing (twisting). Weaving or knitting. De-gumming, dyeing, printing and finishing. Making-up (garments and accessories).
1.6.1 Throwing The throwster is responsible for supplying the weaver or knitter with thrown (twisted) yarns for a specific purpose. Raw silk yarn is generally too fine to be woven with no twist, except for some special fabrics such as habutae which are not made in Europe. This means that several yarns have to be assembled and twisted together to form a substantial yarn for weaving or knitting. The continuous filaments reeled from the cocoons have to be joined together as they enter the twisting frame. It is more convenient for the workers to do this operation at waist level and this is why silk is uptwisted rather than down-twisted, which is usual for other textile fibres. The most common types of twist are: –
Tram: several single yarns assembled and twisted to 100–150 turns per metre.
Silk –
–
29
Organzine: two or more yarns, each of which has been S-twisted and the assembled yarn Z-twisted crêpe: an assembly of several single yarns which have each received a high twist of 2000–3500 turns per metre. Crêpe: an assembly of several single filaments which have each received a high twist of 2000–3500 turns per metre.
Immediately before the thrown yarns are sized they are lubricated, using a mineral oil-based lubricant, to reduce friction during weaving. In silk weaving, a full beam is used, but sectional warping may be employed in the case of weaving dyed yarns into stripes or checks, for example. According to the density of the fabric to be woven, over 20 000 yarns can thus be arranged on the beam in rigorously parallel order and under strictly uniform tension.
1.6.2 Weaving and knitting The thrown yarns are delivered to the weaver or knitter on different types of packaging such as bobbins, cones and perforated tubes. Silk fabrics may be yarn dyed or piece dyed. In the case of yarn dyeing, the yarns are delivered to the dyer generally on skeins or perforated tubes to be dyed before weaving into figured (jacquard) fabrics or other fabrics (e.g. taffeta) made from dyed yarns. The yarns in this case have previously been de-gummed (see below), but in the normal weaving process they still contain the original sericin. This enables the sericin to fulfil its natural function of protecting the fibre from the stresses and strains to which it will be subjected during throwing and weaving. Silk is woven on a wide variety of looms. In countries such as India and Thailand, handlooms are still commonly used. The irregular quality of the silk yarns used and the desire to produce fabrics with a characteristic appearance and feel mean that handlooms will be used for several years. In addition, they have an important social and economic value because they offer employment to a large number of people. In developed silk processing countries on the other hand, handlooms have all but disappeared. They survive in some countries, such as France, Italy and the United Kingdom, for reproducing, restoring or copying ancient fabrics, particularly furnishing fabrics, that can only be woven on the traditional type of loom. In most cases, however, silk is now woven on modern weaving machines, rapier or air-jet, at speeds of up to 450 picks per minute and in widths of up to 270 cm. Because silk is such a small part of total world textile production, no machine builder manufactures looms specifically for weaving silk. Those modern weaving machines designed for weaving filament yarns are intended for synthetic fibres and can operate at high speeds because these
30
Silk, mohair, cashmere and other luxury fibres
yarns are sufficiently level to avoid yarn breaks even when the machine is running at high speed. This means that silk must be as level as any synthetic yarn if it is to be woven efficiently and quickly. Silk lends itself admirably to knitting. Being a naturally highly elastic fibre, its qualities are brought out to the full by the additional elasticity conferred by the knitting process. Knitted fabrics, through their specific structure, give stability, elasticity and comfort. They also have excellent draping qualities and high crease-resistance. That they are not used more extensively is probably due to their higher cost compared with woven fabrics and to a lack of consumer education. Although silk stockings are no longer produced in appreciable quantities, having been superseded by nylon, they were for many years the mainstay of the silk industry, particularly in the United States where, in 1938, 6 pairs of stockings out of 7 were made of silk, a total of 600 million pairs. Silk is knitted on circular, flat-frame, warp, and on special ‘Milanese’ knitting machines. Silk knits are still extensively used in women’s dresses, lingerie and sportswear. Interlock fabrics (such as for dresses) are woven on circular knitting machines as well as silk jerseys (lingerie, sportswear). Milanese is a type of knitted fabric designed to give the maximum resistance to laddering, even when subjected to very high tension.
1.6.3 Fabric types Silk fabrics can be found in an almost infinite number of constructions, but there are four main families of weaves: tabby, sergé, satin and crêpes. Tabby is the simplest form of weave, ‘plain weave’, one warp thread passing over one weft thread then under the next weft thread and so on (see Fig. 1.13). The tabby weave is frequently found in taffeta, made of dyed yarns. Taffeta is a crisp, structured fabric, much in favour for women’s dresses. When the warp and the weft in a taffeta are of different colours, a
Plain weave (tabby)
Satin weave
Twill weave
1.13 Plain weave (tabby), satin and twill point paper designs.
Silk
31
changing effect is produced when the fabric is viewed from different angles. This type of taffeta is known as shot silk, or changeant. Sergé (twill) weaves are characterised by their diagonal appearance and are often used in the manufacture of scarves. Satin is a weave which can be made from almost any fibre although the word ‘satin’ is often misinterpreted as the name of a fibre. The lustrous appearance of satin is due to the large number of warp yarns which are visible. A 6 : 1 satin is one in which each warp yarn covers six weft yarns before it passes under one weft yarn. Crêpes exist in a large number of weaves, some of which can be very heavy to give better draping qualities. All crêpes have a characteristic ‘grainy’ appearance and feel, due to the high twist of the yarns from which they are made. Crêpe-de-Chine is made of a raw silk warp and a crêpe weft, while crêpe georgette is composed of crêpe yarns in the warp and the weft. Satin-backed crêpes are popular in fashion garments. One of the most luxurious applications of silk has always been velvet. Silk velvet continues to be manufactured in relatively small quantities. There is still considerable production of ‘burn-out’ velvets, which are made from two fibres, usually silk (for the backing) and viscose (for the pile). In this type of fabric, the pattern to be picked out is protected from the rest of the pile of the velvet. The whole fabric is then subjected to an acid treatment, which ‘burns out’ the unprotected parts of the pile, leaving the desired pattern in relief. The chemical used does not affect the base fabric.
1.6.4 De-gumming and weighting Once the fabric has been woven or knitted, it is almost ready for dyeing, printing and finishing. There is one important operation before these processes can be undertaken.As has been stated, the silk fabric (at this stage still a ‘grey’ fabric) contains the original sericin. However, the sericin has two disadvantages: it gives the fabric a stiff, cardboard-like feel and it prevents dyestuff from penetrating into the heart of the fibre. It therefore has to be removed before dyeing or printing. (There are some exceptions, such as organza, in which the sericin is only partially removed and the fabric is said to be ‘dyed in the gum’.) The sericin is removed by de-gumming or boiling off. This is a critical operation in the preparation of the fabric for further finishing. If the grey fabric is unevenly boiled off, some traces of sericin will remain on the yarn in places. The fault is difficult to detect before the fabric is dyed. After dyeing, when it is too late, this fault will appear as differences in shade in the finished fabric. The traditional method of de-gumming involves the use of olive oil (‘Marseilles’) soap as shown in Fig. 1.14. The fabric is soaked for
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Silk, mohair, cashmere and other luxury fibres
1.14 Bath of olive oil solution.
1.15 Silk fabric mounted on a star frame for de-gumming.
Silk
33
6 hours in a solution of Marseilles soap (3–5 g/l at 40–50 °C) then boiled off for 2–6 hours using a solution of soap at 8–10 g/l at 90–95 °C. The fabric is hooked onto a ‘star’ frame equipped with small hooks (see Fig. 1.15) and once installed resembles a loosely rolled cylinder of paper. The ‘star’ is then gently raised and lowered in the soap-and-water solution. After degumming, the silk is bleached in a bath of hydrogen peroxide (35 %, 15–20 ml/l) and rinsed in clean water. The text above details the procedure for Bombyx mori silk, but tussah silk has a natural yellowish-brown colour which it is practically impossible to remove totally without damaging the fibre. De-gumming also serves to remove the oiling and sizing auxiliaries used in weaving. Although this is the traditional and gentlest way of de-gumming silk it is also slow and expensive, and olive oil soap is not available everywhere. Other de-gumming methods have been developed using enzymes or hot water at very high pressures, but the silk purists would still say that olive oil soap continues to be the best de-gumming agent. After washing and drying the fabric is ready for printing or dyeing. The difference between a grey fabric and a boiled-off fabric is quite spectacular. Before de-gumming, the cloth is stiff, dull and unattractive; after the process the fabric ‘breathes’ and is lustrous and supple; in other words, it now feels like silk. The weight lost in de-gumming must be made up, and this process is known as weighting. Sericin accounts for approximately 25 % of the weight of the yarn so the de-gummed fabric weighs 25 % less than before the process began. This weight loss has to be made up, not only to recover the initial weight of the fabric but to give it sufficient body and draping qualities. The return to the original weight is known as weight-for-weight, but in some cases, when a particular feel or bulk is required, the weighting added to the fabric may exceed the 25 % of the weight removed in de-gumming. Silk was traditionally weighted using tin salts or stannic acid, which had the added advantage of conferring flame-resistant properties to the fabric. Mineral weighting is no longer used partly because of the expense involved and partly for ecological reasons. In some countries weighting by means of tin salts is prohibited. Nowadays, silk is weighted using a different method, known as chemical grafting. Instead of applying a weighting agent to the fabric as a whole, the finishers graft a molecule of methyl methylacrylate to the polymers of the silk yarn. This chemical action achieves the desired result of restoring bulk to the fabric without altering its ‘hand’. Some weavers continue to use de-gummed, non-weighted silk which is officially known as ‘pure silk’, whereas weighted silk is ‘all silk’, i.e. no other fibre is present. European legislation does not take into account the presence of such substances as weighting agents or dyeing auxiliaries in the
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Silk, mohair, cashmere and other luxury fibres
definition of a fabric as ‘silk’. What is important in the labelling of silk as ‘100 %’ is that no other fibre is present.
1.6.5 Dyeing and printing 1.6.5.1 Dyeing Silk has excellent dyeing affinity and is capable of rendering colours in a unique way. The silk fibre is triangular in section and when several yarns are twisted together they offer a number of facets that reflect light rather in the same way as a diamond is cut to give maximum brightness. Yarn dyeing is the traditional method of dyeing fibres and practised throughout Asia. In Europe, yarn dyeing is still used when weaving jacquard, striped, checked or ‘shot’ designs. The commonest method of dyeing, piece dyeing, was developed in Lyon in the nineteenth century. Today, silk fabrics are dyed using different types of dyestuff: acid, metallic, reactive, and vat. One of the problems facing contemporary silk dyers is the relatively small number of dyestuffs available on the market. Once again, because of the small quantities of fabrics that silk represents, it is no longer possible to find dyestuffs specifically designed for silk because they are of little interest to the dyestuffs manufacturers. Very often dyers have to substitute dyestuffs designed for other fibres, particularly wool, which is also a protein fibre. In addition, European legislation on the protection of consumers and of the environment has banned the use of certain azoic dyestuffs because they are potentially carcinogenic. Some of the brightest hues which used to characterise silk are no longer possible because these dyes have to be fixed using certain agents that contain, for example, chromium whose use is also banned. With the decreasing number of chemical dyes available and more and more pressure from the legislator, there is increasing interest in returning to the use of natural dyes, such as indigo or madder. The difficulty in producing natural dyes is that they require large areas of land for small quantities of dyestuff, land which could more profitably be used for food production. Furthermore, natural dyes are not usually fast to washing.
1.6.5.2 Printing One of the areas in which silk can best express its unique characteristics is in prints. Printing is a technique which has never ceased to evolve over the centuries, from block printing to screen printing. Nowadays, screen printing is the most common method of printing silk, although roller printing may be used when long runs are called for. Screen printing is a relatively long
Silk
35
and complex process, consequently it is expensive. Some designs call for as many as 32 colours and this means preparing 32 screens. The dyestuffs used in screen printing contain gum arabic, used to thicken the dyestuff and ensure it does not migrate outside the limits of each individual yarn to which it is applied but remains precisely within the area intended by the designer. Once the entire design has been completed, the gum is washed out, the dyestuff can penetrate the fibre and the contours of the design remain sharp. Another printing technique, discharge printing, is also commonly used to print silk fabrics. This process consists of dyeing the fabric uniformly then removing the dyestuff within the area of the design to be printed. The fabric is then printed over the spaces left free after discharge. Printing technology continues to change and the latest development is ink-jet printing, derived from the computer industry. It is as yet too early to say how far ink-jet printing will replace screen printing, because it remains relatively slow and expensive. Nevertheless, silk printers are all seriously studying this new possibility and there is every chance that it will find an application in printing silk each time short runs and rapid changes of colour are required.
1.6.6 Specific finishes Various finishing treatments can be applied to silk to give it special characteristics, for example ‘scroop’. Scroop is at the same time the familiar rustling sound produced by a silk fabric when it is handled and the ‘crackling’ handle which accompanies it. The effect is achieved by a special treatment using an organic acid such as formic, lactic, citric or acetic in a concentration of 2–4 ml/l. Other forms of treatment are intended to make the fabric crease-resistant, waterproof, spot-resistant and so forth. The art of finishing consists of enhancing the natural suppleness and brilliance of silk without altering its ‘hand’. Theoretically, it is possible to apply a finishing treatment to silk to make it more easily washable, even in a washing-machine. One such treatment consists of coating the fibres with a silicone-based product. The danger is that the resulting fabric will no longer feel like silk.
1.7
The care of silk
There is no doubt that many potential customers are afraid of buying silk because it has a reputation of being difficult to wash and iron. Silk is often described as ‘delicate’ or even ‘fragile’ with regard to its care characteristics. Part of the problem is that today’s consumers are used to fabrics which
36
Silk, mohair, cashmere and other luxury fibres
are ‘easy care’ and made of fibres such as polyester that can be washed in a machine and often do not require ironing. As we mentioned above, silk is a natural microfibre. When the silk fibre is wet, i.e. swollen with water, it becomes extremely sensitive to abrasion. Putting silk into contact with other, rougher fabrics or with the metal drum of a washing-machine will expose it and cause chafing. Many a housewife has had the disagreeable experience of washing a navy blue silk blouse in the washing-machine and discovering afterwards that it seems to be covered with white patches or streaks as if icing sugar had been spilled on it. This defect is often attributed to a loss of dyestuff when in fact it is due to chafing. The outermost layer of microfibre has been brushed up off the surface of the fibre and these fibrils reflect light. During processing, before and after printing and dyeing for example, silk is frequently exposed to water without suffering any damage. The difference between the industrial processes and domestic washing is in the quantity of water used. The drive for ‘economic’ washing cycles in a typical washing machine means that the bath ratio between the weight of laundry in the wash and the quantity of water is very low, so the silk items in the wash are not as well cushioned against abrasion as in industrial washing. It also means that the quantity of detergent in relation to the amount of water is relatively high. Fortunately, modern washing machines are often equipped with a ‘gentle’ washing cycle, designed for wool and other delicate fibres. In this type of cycle, the temperature is low (30–40 °C) and the drum, instead of completing a full revolution is ‘rocked’ backwards and forwards. Under these conditions, many silk items can be washed in safety. The other alternatives to machine-washing with a special gentle cycle are hand-washing and dry-cleaning. Hand-washing is recommended for silk, providing the proper precautions are taken: – –
– – – –
The temperature of the water must be about 30–40 °C. The detergent must be non-aggressive. It is recommended to use a gentle, liquid detergent as a powder may not completely dissolve in the water giving a possible risk of abrasion. Detergents designed for wool will adequately wash silk, some consumers even use shampoo but care must be taken not to produce too many suds as this could cause problems in some types of washing-machine. The ratio of water to fabric must be high. The fabrics or garments must be washed separately, i.e. not washed together with other, more abrasive items. The fabrics or garments must not be rubbed, screwed up into a ball or wrung in the wet state. Excess water should be squeezed out and the silk item dried flat.
Silk
37
The care method most frequently recommended by manufacturers of silk garments is dry-cleaning, which is the safest method of cleaning in comparison with hand-washing or machine-washing, unless these are conducted under optimal conditions. But dry-cleaning has other drawbacks. It is inconvenient to have to go to the dry-cleaner’s and come back to pick up the goods. Dry-cleaning is also relatively expensive and the process often leaves a disagreeable odour on the garments. In addition, the traditional drycleaning process is destined to change for ecological reasons, in particular through the elimination of potentially harmful chemical solvents. In the near future, dry-cleaning will become ‘wet-cleaning’, with the gradual inclusion of more and more water in the process. Everything points to careful hand-washing as being a sensible answer to the problem of silk care, with one notable exception. Silk ties should never be washed because of their structure, which is based on a tie-fabric, a lining and an interlining. These three fabrics are liable to behave in different ways when subjected to water and there is a serious risk of distortion if a tie is washed in water. Modern consumers are often reluctant to wash by hand unless it is strictly necessary and this is certainly an obstacle when encouraging more people to buy silk. Attempts to add a finishing agent to silk to make it washable have always resulted in an alteration of the hand of the silk, so this is not really a step forward. For the consumer, there has to be a trade-off between the incomparable qualities that silk offers and its lack of easy care. For the silk manufacturer, it is vital to educate the consumer in the characteristics of silk and remove his or her fears of looking after it. When ironing, it is important to know that silk should always be ironed damp, with a cool iron and on the ‘wrong’ side of the garment or fabric.
1.8
Sand-washed silk
As we have seen, silk always had a special place among textile fibres. It was considered the luxury fibre, partly because of its peerless qualities and partly because of its relative scarcity. This positioning of silk at the summit of textiles was to change radically in the late 1980s and early 1990s with the arrival of sand-washed silk. This new treatment of silk, that originated in the United States but was mainly exploited in Hong Kong and China, was a revolution in the way in which the public looked on silk. From now on, silk was to be found in places other than in up-market garments and accessories. So what exactly is ‘sand-washed’ silk? ‘Sand-washing’ has nothing to do with sand. The term is derived from ‘stone-washing’, a process used to treat denim jeans in which pumice stones
38
Silk, mohair, cashmere and other luxury fibres
are used to soften the fabric and remove some of the dyestuff. The sandwashing process, based on enzyme treatment and/or mechanical abrasion, is a deliberate reproduction of the fibrillation defect to which silk is prone. In sand-washing, a normal silk fabric is deliberately roughened to produce fibrillation over the whole surface and not just in some places where it is an accident of the washing-machine. After the individual fabrics have been treated in this way, a softening agent is added. Garments made of sand-washed silk are characterised by their soft feel, their lack of lustre and by a distinctly limp or ‘distressed’ appearance. For several years, sandwashed garments were very successful because: – – –
They were low-priced. They looked and felt natural. They were different from the lustrous, smooth and structured traditional silk garments.
Sand-washed silk garments consequently found a ready market among young consumers who had heard so much about silk but had never been able to afford it. This was particularly true for young women who had heard about silk from their mothers or grandmothers but for whom silk was something they saw in the glossy magazines. Suddenly they were able to buy silk garments at a price equal to (and sometimes lower than) the price of an equivalent polyester garment. Before the arrival of sand-washed silk almost the only silk items men would normally wear were silk ties or the occasional dressing-gown. However, sand-washed silk opened up a large market in casual wear for men but manufacturers of these goods, in their desire to capture a massmarket through low prices, often economised on quality. The initial craze for sand-washed silk started to wear off when the consumers, women and men, began to be disappointed by the overall quality of the garment. The sand-washing treatment is a deliberate degradation of the fibre, which is consequently weakened by the abrasion of its outermost layer. If the original fabric is not strong enough, and in particular if the weave is not dense enough, the fabric itself will also be weakened. In addition, the chemical finish applied to give the sand-washed garment a soft feel wears off in the wash, and then the fabric becomes stiff and disagreeable. In 1994 the European Union, under pressure from the silk textile industry, imposed quotas on the import of Chinese silk garments, blouses in particular, which were often made of sand-washed silk. The objections raised by the European silk industries were founded less on a question of direct competition than on a question of image. Silk, traditionally the most prestigious of all fibres, was now being offered at rock-bottom prices in supermarkets, department stores and even on street markets. It should be added
Silk
39
that the sand-washed phenomenon was exploited by these distributors of inexpensive clothing, rather than by the traditional textile trade. The consumer was also confused because, with no thorough knowledge of what constitutes the quality of a silk garment, it was difficult to understand the enormous price differential between an imported silk blouse sold in the local supermarket and the designer blouse in the High Street boutique. The professionals of the silk industries in Europe consider sandwashed silk as an aberration with regard to the traditional image of silk that is associated with luxury, quality and exclusivity. In any event, independently of the European quotas, the consumer was already beginning to turn away from sand-washed silk because of quality problems. In particular, some consumers had the disagreeable experience of seeing their silk blouse literally come apart at the seams. The statistics are eloquent. In 1994, the year quotas were introduced, Europe consumed 5674 tonnes of silk garments. In 1995, the figure had dropped to 3141 tonnes and by 1998, Europe consumed only 1701 tonnes.
1.9
The market position of silk
1.9.1 The organisation of the silk industry In terms of market positioning, silk has two characteristics which make it ill-suited to the mass-market: –
–
It is not only a very rare fibre (it constitutes about 0.2 % of total textile fibre production) but its production cannot be easily or quickly increased. It is relatively difficult to look after in terms of household care and cannot offer the convenience of synthetic fibres.
This suggests that the place of silk is to be something other than a massmarket fibre. From the most ancient times, silk has always been an inspiration for textile creation, not only artistic creation in the sense of colours and designs, but creation in a wider sense of innovation. Although silk is not as widely used in Europe today as it was before the Second World War, it remains the inspiration for fashion designers. The top fashion designers always include a significant percentage of silk dresses in their collections, and these dresses are considered as the highlights. Fashion designers have never ceased to consider silk as the ultimate reference because of its inimitable qualities of texture, brilliance and beauty. The areas in which silk continues to be used in the west are: –
The fashion industry: silk continues to be the ideal mode of expression of the top fashion designers.
40 – – –
Silk, mohair, cashmere and other luxury fibres Lingerie: silk is still the irreplaceable fibre for luxury underwear. Accessories: scarves and ties are the vehicles of the most elaborate prints. Furnishing: silk furnishing fabrics are widely used for the most prestigious decoration. Silk can meet the most stringent non-flammable regulations.
The major silk producing and processing countries are grouped together in an international body, the International Silk Association (ISA).This association was founded in 1949, following a constituent congress held in Lyon and Paris in 1948. Prior to the Second World War, Japan was the chief producer and supplier of raw silk, so the silk trade was totally disrupted by the hostilities. Following the end of the war, General Douglas MacArthur, as head of the provisional government of Japan, was anxious to revive the whole of Japan’s industry, which had been seriously damaged by the war. He decided to begin by re-establishing the silk industry, first of all because of the important role of silk in Japanese culture and traditions and also because silk had been the basis for Japan’s industrial development at the end of the nineteenth century. It was the revenue from the silk trade which had fuelled Japan’s industrial revolution. With the collaboration of the French silk trade, an initial congress was held in June 1948 and the major decision of this congress was to set up an international federation of silk producers, industrialists and traders. The statutes of ISA were drawn up the following year in Zürich, and the headquarters of the Association were settled in Lyon, which at that time was the centre of the silk industry. Today, ISA counts 40 member countries, including all the major producers such as China, India, Brazil, Uzbekistan and Brazil, as well as the top silk consuming countries. ISA is responsible for setting international standards for raw silk and trade rules for the raw silk trade. It also helps to promote silk and defend the proper use of the word ‘silk’ and its derivatives. It is also the only organisation which brings together every sector of silk activity, from cocoon production to the finished article.
1.10
Silk production and trade today
1.10.1 Sericulture Silk production is often envisaged as an excellent activity to help solve the problems of developing countries because of the numerous advantages it seems to offer: –
Sericulture is first of all an agricultural activity. It could therefore be one way of halting rural exodus by offering an additional source of revenue to poor farmers.
Silk –
–
–
41
In countries where sericulture is well-developed, farmers can expect to receive on average $2 per kilo or more for their cocoons, which is a much higher unit price than for many other cash crops. In addition, sericulture is not a strenuous activity and can involve all family members, leaving the head of the household more time to look after the basic subsistence of the family. Sericulture is environmentally friendly because mulberry trees need little fertiliser and no insecticides can be used for fear of poisoning the silkworms which feed on the mulberry leaves.
However, this idealistic view of the value of sericulture in developing countries must be tempered by some practical considerations. One of the most tenacious misconceptions about sericultural start-ups is that silk production is a simple activity that can be undertaken with a minimum of investment. Nothing could be further from the truth. If a new sericultural venture is to be ultimately successful it must begin with a serious plan stretching over several years. This plan must start from a marketing outlook rather than from a simple production objective. It is obviously dangerous to begin by saying ‘let’s start by producing raw silk and then see how (or if) we can sell it on the export market’. This plan must incorporate the precise objectives of the project. Is it designed to produce raw silk for export? Is it intended to use its raw silk production in the local textile industry? Is the ultimate objective to produce raw silk, fabrics or garments? The answers to these questions will determine the nature and the scope of the project and consequently the level of investment required. In any event, the investments required are substantial, not only to buy and prepare the land and to purchase mulberry saplings and eggs but also for the following: – – –
To provide for irrigation where required. To set up proper grainage and selection procedures so as to produce parental strains of silkworms adapted to local conditions. To create training and extension services.
In general, it takes two to three years, according to the climate, for a mulberry tree to produce enough leaves to feed silkworms. There must therefore be sufficient will on the part of the authorities responsible for the project to keep going throughout the initial period when substantial investments are being made but no revenue is coming in. The experts in this field agree that a country with no sericultural tradition that decides to undertake a sericultural project will take a minimum of ten years to produce any tangible results, at least in terms of exportable products. This is a long time to wait for a return on investment.
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Silk, mohair, cashmere and other luxury fibres
1.10.2 World production and international trends There are at least 50 countries producing silk throughout the world, with a production ranging from over 38 000 tonnes of raw silk in China (1999) to 20 tonnes in Turkey. The major producers, with the exception of Brazil, are all in Asia. China is the world’s largest producer of raw silk, followed at some distance by India. Table 1.3 shows how world raw silk production has evolved over a ten year period (all figures in tonnes). It is difficult to obtain accurate figures for raw silk production because of the areas and conditions in which it is produced. The farmer who produces a few kilos of cocoons which he sells on the local market is not necessarily recorded in official figures. This is why the figures shown are to be considered as estimates. To compare how silk production has developed, it should be noted that production in 1939 was just under 54 000 tonnes. It is clear from the figures given that overall raw silk production is declining and the causes of this decline are explained elsewhere. Sericulture and raw silk production are notably labour intensive activities. This means that the overall economic conditions of the producer country play an important role in the way its production develops. There are no longer any significant quantities of raw silk being produced in Europe, except in Bulgaria, which continues to produce about 60 tonnes per annum.All the other erstwhile European producers, France, Italy, Spain, Portugal and Greece stopped their production when it became uneconomic to continue. There is a distinct connection between industrialisation and the
Table 1.3 Estimated world raw silk production (tonnes), 1989–98
China India** Japan Brazil** Uzbekistan* Vietnam Thailand Iran North Korea South Korea Others Total
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
40 800 10 020 6 060 1 680 4 020 na na na 1 000 1 200 2 120 66 900
43 800 10 800 5 700 1 680 4 020 na 1 503 381 1 000 1 200 1 719 70 983
48 480 10 800 5 520 2 100 4 020 na 1 612 385 1 300 1 000 1 615 76 732
54 480 12 600 5 100 2 280 2 160 na 1 589 423 1 200 910 1 677 82 419
69 300 13 200 4 200 2 340 1 800 na 1 229 427 1 200 840 2 801 97 337
72 000 13 200 3 900 2 520 1 800 na 1 377 396 1 200 491 3 504 100 388
77 900 12 884 3 240 2 468 1 320 2 100 1 313 750 600 346 2 217 105 138
59 000 12 927 2 580 2 270 1 568 1 500 1 144 600 360 146 2 165 85 192
55 117 14 048 1 920 2 120 1 500 834 1 039 500 200 72 1 666 79 590
49 430 14 500 1 080 1 821 1 500 862 900 400 150 60 1 438 71 727
* estimate ** silk year April/March or September. Source: ISA National Statistic Bureaux.
Silk
43
decline and eventual disappearance of sericulture, and this statement can be confirmed on examining the situation of all the European countries listed above. In the latter half of the nineteenth century, competition for jobs, better working conditions and higher wages in industry as well as competition from other fibres sounded the death-knell of sericulture in France and later in Italy. This is a universal phenomenon, not confined to Europe. An economic study of the financial aspects of sericulture made by a Korean specialist goes as far as to define the actual level of national revenue at which sericulture ceases to be economically viable. Korean raw silk production today stands at about 60 tonnes, whereas 25 years ago Korea was still producing over 6000 tonnes. In the case of Japan, which has been an industrialised country for much longer than any other Asian nation, the same phenomenon ought to have happened a long time ago. However, sericulture is so deeply rooted in the Japanese national psyche and the traditions of the country that it has a value that goes much deeper and much further than its purely economic aspects. For this reason, the Japanese government for many years continued to support sericulture with heavy subsidies, long after it became objectively uneconomic. This well-managed but highly expensive policy enabled sericulture to go through a gentle decline rather than an abrupt downfall. However, the decrease in Japanese cocoon and raw silk production is now accelerating. Japan, as a member country of WTO, cannot continue artificially to support its sericulture. In addition, the silk farmers are generally very old and their successors are reluctant to follow in their footsteps. In 1999, raw silk production in Japan declined to just over 1000 tonnes. Sericulture is a difficult job. It involves long hours and it is subject to the vagaries of the climate and of the overall market for cocoons. As soon as silk farmers and their children have the chance of earning a better and more reliable livelihood from other agricultural products they will abandon their cocoon production. There is a question mark over the future of world raw silk production and it concerns the major producer, China. The standard of living of the Chinese people is rising rapidly. The Chinese farmer is increasingly independent in the choice of crops he wants to produce, so if he cannot earn as much from cocoon production as he can from food crops or raising pigs he will switch away from sericulture. Silk is produced in the majority of China’s provinces. The province with the largest production is Sichuan. The provinces with a reputation for producing the best qualities, i.e. the higher grades of raw silk that are exported to Europe and Japan, are Zhejiang and Jiangsu. These two provinces, situated in the orbit of Shanghai, are precisely those that are industrialising the most quickly. The consequences are:
44 – – –
–
Silk, mohair, cashmere and other luxury fibres Agricultural land, including that devoted to mulberry plantations, is being built over with factories, housing, shopping-centres and highways. The new industries often bring added pollution that is extremely harmful to the remaining mulberry trees. Farmers can earn a better livelihood producing food for the enormous population of the region around and including Shanghai, and many of them are giving up sericulture. It is becoming increasingly difficult to find girls willing to work in the reeling mills, which is quite understandable. Instead of standing all day long with their hands in very hot water reeling cocoons, the girls now have the option of working in a clean, well-lit factory assembling television sets or portable telephones.
In other words, these two provinces of China are beginning to reproduce, in socio-economic terms, exactly the same situation that existed in the Rhône valley in the late nineteenth century. The Chinese authorities are, of course, perfectly aware of the situation. Already they are beginning to transfer sericulture to inland areas of the country where it has not been highly developed until now. Many experts are concerned, however, about how long it will take for these new sericultural regions to reach the quantities and above all the standards of quality that the international silk market requires.
1.10.3 The international silk trade While there are a great many countries producing silk, there are only two countries exporting any appreciable quantities of raw silk, namely China and Brazil. All the other producing countries consume their own production (Japan) and in some cases supplement their local production by imports (India). The silk processing countries are reduced to two sources of supply of raw materials, China and Brazil, which is an uncomfortable situation. The two basic conditions for exporting raw silk are quality and price. The modern textile machinery used in Europe and Japan requires raw silk of a very high quality. In the International Silk Association’s grading system, 3A is the minimum grade which can be accepted and usually 4A or 5A would be preferred. China and Brazil are, for the time being, the only two countries capable of supplying raw silk of this quality. However, with the introduction of modern textile machinery in China, this country increasingly needs its own higher qualities of raw silk. The preoccupation of the silk processors is that production is declining in China and Brazil, while importing countries depend more and more on these two sources for their supplies, with the result that raw material sup-
Silk
45
plies are being squeezed from both sides simultaneously. As was previously stated, Japan is no longer a major producing country but remains a very large consumer and is increasingly dependent on Chinese raw silk to feed its processing industries. The Republic of Korea, which has almost ceased to exist as a producer of raw silk, is obliged to import more and more from China and Brazil. In recent years, the problem has been masked by the fact that demand for silk was also declining. The financial and economic difficulties of several Asian countries made them reduce their silk consumption. In Europe, silk gradually fell out of favour, due in part to the negative impact of cheap imports and due in part to competition from other fibres. Today, however, there are signs that demand for silk is increasing. Most Asian countries are climbing out of their economic inactivity and beginning to buy silk again. In Europe, colour is coming back into fashion after many years dominated by black and grey, the ‘grunge look’ as it was known in the UK and US. Since silk is the ideal vehicle for bright colours, silk consumption is likely to increase again. China’s silk production has decreased for two reasons: (a) some silk farmers have turned away from cocoon production because it is not profitable enough and (b) because the Chinese government has voluntarily reduced supply in view of falling demand. Many small reeling mills were closed in 1996 and 1997 because demand was poor and the quality of their production was low. Now that demand is increasing again, there is a definite risk of lack of raw silk supplies if only because of the time it takes to increase production. Silk is not nylon or viscose. If there is a sustainable demand for either of these fibres, a new plant can be up and running in under two years. In the case of silk, the time-span is much longer. There are two cases. If the silk farmer has neglected his mulberry trees but left them standing he could resume production relatively quickly. On the other hand, if he has uprooted his trees to replace them with some other plants it will take a minimum of three years to replant new mulberry trees and have them produce leaves again. Brazil is the only other source of quality raw silk supplies. In fact, Brazil is an exception in the world of silk in the sense that is the only remaining country which is a producer/exporter of raw material with practically none of its production used domestically. Raw silk production in Brazil, which used to stand at roughly 2200–2400 tonnes per annum, is now down to 1400–1500 tonnes. Brazilian farmers expect a higher price for their cocoons than Chinese farmers, so unless the market is very strong and prepared to pay high prices, many farmers will not continue in sericulture. This is what is already beginning to happen. There has been, over the past 20 years or so, a considerable change in the silk trade. In the past, China was essentially an exporter of raw or semi-
46
Silk, mohair, cashmere and other luxury fibres
finished materials. The European industries imported raw material and processed it through all the relevant phases up to the finished product. China is now involved in exporting silk at every stage: raw silk, thrown silk, grey fabrics, finished fabrics and garments.This is due to China’s natural desire to export goods with added value. The quality of Chinese fabrics has improved, as China uses more and more up-to-date machinery such as that used in Europe. This also implies that China will increasingly need the higher grades of the raw silk it produces for its own processing industries, whereas previously the better qualities were exported. When it comes to dyeing or printing silk fabrics, it is no longer viable for European processors to buy the basic weaves they need in Europe. Providing the quality is equal, it is more profitable to import Chinese grey fabric to be used as a printing base, except when absolutely perfect quality is required or when more complicated weaves are needed. The latest development in this sense concerns thrown yarns. Europe and Japan are importing more thrown silk yarns and less raw silk. If this trend continues, it could represent a serious threat to the future of the European throwsters. A special mention must be made of Hong Kong, which plays a major part in world trade in silk. Hong Kong is not only a centre of silk processing, it is an important centre of trade in silk products, because of its banking facilities, its commercial dynamism and of course the fact that it is now a part of China. It is thus a centre of exchange between China and the rest of the world. In 1999, Hong Kong was the chief destination of China’s overall silk exports, for a total value of US$64 million. The main destinations of re-exports of these silk goods were: – – –
Raw silk: India, South Korea, Italy, Japan. Silk fabrics: Mainland China, South Korea, Italy, Singapore. Made-up goods: United States, European Union, Japan.
The pattern of Hong Kong’s silk trade for 1998 is as shown in Table 1.4.
1.10.4 Raw silk prices Price is, after quality, the second consideration to be taken into account when a country exports raw silk, but the relationship between quality and price is not a simple one. Basically, if the quality is right, exporters can ask a high price for raw silk, within certain limits. On the other hand they can try to sell as cheaply as they wish, but if the quality is inadequate nobody will buy. The silk market seems to contradict one of the basic laws of supply and demand, namely that when prices are low the customer will buy more, but this is only an apparent contradiction. No-one buys on a falling market
Silk
47
Table 1.4 The Hong Kong silk trade 1998 (US$ ’000) Imports
Cocoons Raw silk and dupion Waste silk Thrown silk yarns Spun silk Blended spun silk yarns Fabrics Finished products Total
Re-exports
Exports
Consumption or stocks released
0.04 1 495 374 102 2 224 619 4 169 9 857
7 1 667 294 236 1 655 409 3 678 8 293
0 0 0.06 3 1 5 68 1858
7 (172) 81 (136) 572 205 423 297
18 859
16 239
1953
667
Note: Numbers in brackets show decrease in stock over the year.
unless it is a question of fulfilling outstanding orders. On the other hand, when prices are rising it is wise to buy early to build up stocks and hedge against further rises. These two reactions to market prices accentuate price fluctuations and contribute to the notorious ‘textile cycle’. The ideal situation for the silk trade is one in which prices are increasing gradually and in a foreseeable way. The worst scenario is one in which prices fluctuate unpredictably, as was the case in the wake of the first oil crisis in the 1970s. Chinese raw silk prices reached the highest level known in 1988–9 at $51 per kilo. European raw silk consumption in 1989 was 5605 tonnes. In 1998, when China’s raw silk prices dropped to a level of little more than $20 per kilo, Europe’s consumption was barely over 3000 tonnes. The main reason for this apparent paradox is given by the very long lead times which characterise the silk business. From the moment when orders for raw silk are placed and the finished products appear on the market several months may elapse. Silk industrialists want to be sure that their product can be sold at a price which reflects its true value so they will have confidence in the market if prices are at least steady and preferably increasing. On the other hand, if the price trend is downwards, buyers will postpone their purchases. There is no international commodity price for silk as there is for substances such as coffee and tin because there are so few players in the field. The Chinese price is the de facto international price. Brazil has to align its prices in relation to the Chinese price but at a higher level because Brazilian cost prices are higher than those of China. Brazil’s main outlet is Japan, which is prepared to pay a high price for Brazilian silk because it will still be cheaper than Japanese raw silk and also because two of the three Brazilian silk reelers are of Japanese origin. In Europe some raw silk users are prepared to pay a premium for Brazilian raw silk because it offers a guar-
48
Silk, mohair, cashmere and other luxury fibres Table 1.5 Raw silk prices 1990–2000 (US$/kg) Year
Price
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
51.00 43.50 35.00 29.00 24.50 27.50 25.50 24.50 27.50 21.10 22.20
antee of regular quality. In France, just over 50 % of raw silk imports come from Brazil, a much higher percentage than in any other European country. In the early months of 2000, prices started to rise again, thus restoring some confidence in the market. Over the period 1990–2000 raw silk prices showed a generally declining trend, with minor fluctuations in the course of each year. The prices given in Table 1.5 are the official Chinese prices in US$ in Beijing for 2A 20/22 denier raw silk on 1 January of each year. The actual prices may vary a little according to the size of the order and to availability at the time of the contract.
1.11
Silk producing countries
1.11.1 China China holds a pivotal position in the world silk trade. It is the largest producer country and the largest exporter. China’s raw silk production at present stands at over 38 000 tonnes but 5 years ago it was 70 000 tonnes. It was in the 1970s that China overtook Japan as the world’s chief source of raw material. At that time, Japan’s production was beginning its long decline and overall demand for raw silk was increasing. For many years, China exported mainly raw silk, spun silk and grey fabrics. Gradually, however, it began to export finished fabrics and after that garments. In the early 1990s, garment exports accounted for the majority of China’s export earnings in silk. The value of China’s total silk exports reached $2.1 billion in 1999. The silk trade is a microcosm of what is happening in every aspect of China’s current economic situation. Following Deng Xiaoping’s directives that the Chinese people should strive to become more prosperous and that
Silk
49
businesses should become more self-reliant and less dependent on state subsidies, there ensued a gradual loosening of central power. In China, the state body in charge of the silk trade is the China National Silk Import and Export Corporation, based in Beijing. The Corporation has branch offices in the main silk producing regions of the country. When there was still a large degree of centralisation, silk prices were standard throughout the country but today the branches are increasingly independent of Beijing. They also have to be profitable in their own right. Consequently, they are in competition with each other and this competition often takes the form of price cutting. The Chinese economy is somewhere between a centrally controlled economy and a free-market one and this is nowhere more obvious than in the silk business. In this context, it is difficult to predict how silk production will evolve in China. However, silk is such a valuable export product, with current earnings around $2.1 billion, that the Chinese authorities will certainly take the appropriate measures to safeguard their raw silk production and their industry. One thing is certain, there is no other country in a position to replace China as the major supplier of raw silk to the processing industries, so the processing countries will continue to depend on China for 80 % of their raw silk requirement for many years to come.
1.11.2 India India has its own tradition of silk production, and it is quite possible that India knew how to exploit wild silkworms before it began to use Bombyx mori silk introduced from China. Indians specialise in hand-woven fabrics, those of Varanasi (Benares) being particularly famous for their rich colours and their complex designs. Over 60 000 villages are involved in silk production in India today. Total production of Bombyx mori silk is almost 15 000 tonnes, mainly concentrated in the state of Karnataka. The vast majority of this Bombyx mori silk comes from multivoltine strains or bi/multi hybrids. These are hardy varieties well adapted to the specific climatic and rearing conditions prevalent in the sub-continent. They have some drawbacks, however. They are not very productive (400–800 metres of yarn per cocoon) and the quality of the yarn is poor compared with bivoltine Bombyx mori silk. One way of solving the problem is the further development of bivoltine/multivoltine hybrids. Another solution is the introduction of bivoltine strains in the north of the country, where the climate is more congenial to these varieties. In the traditional producing areas (such as Karnataka) there is a certain resistance to the introduction of bivoltine strains because in shape, size, colour and general appearance the cocoons differ so widely from the small, hairy, yellow multivoltine varieties.
50
Silk, mohair, cashmere and other luxury fibres
Raw silk produced in India is totally consumed on the local market. The overall quality is not of international standard and, in any event, the Indian government gives priority to the export of value-added silk goods rather than raw materials. India has several other characteristics which differentiate it from China and other countries. Although it is the second-largest producer country, India exports no raw silk, although it does export waste silk and spun silk. Several Indian manufacturers are installing modern weaving machinery, particularly for the production of high-quality furnishing fabrics aimed at the export market. Since domestically produced silk does not have such qualities as evenness required by this equipment, India is obliged to import upwards of 5000 tonnes of raw silk from China, Brazil, Vietnam and North Korea. The Indian government has recently liberalised imports of raw silk as a means of fostering silk fabric and garment exports and the effects of these measures can be seen in Chinese raw silk exports to India, which increased by 28 % from 1998 to 1999. India is also fortunate in having a buoyant domestic market for silk fabrics and garments. Silk is familiar to Indians, particularly in the form of saris. Contrary to the Japanese national dress, the kimono, which is rapidly losing ground, the demand for saris remains very strong in India. Although India is often seen as a poor country, there are approximately 80 million consumers of silk. One reason for the success of silk saris is the number of occasions when an Indian woman can wear one, notably for festive and religious events. One of silk’s numerous connotations is its spiritual value, which makes it the fibre par excellence to be worn on the occasion of diwali, for example. India exports furnishing fabrics and large quantities of dupion. Indian dupion is considered by the specialists as the most lustrous, and its most frequent application is in bridal wear. Indian fabrics are highly appreciated for their texture and colour. They are instantly recognisable, and this is one reason why they are being exported in increasing quantities. They also benefit from a demand for ethnic designs and textures, particularly in Germany and the United States. In the United Kingdom, they find an outlet among the large population there of Indians and Pakistanis. They also hold a strong market position in the Middle East. Although silk generally is going through a relatively difficult time, in common with other textile fibres, India is in a comparatively strong position. In addition to this strong domestic market, India is enjoying increasing success with its exports of silk fabrics and garments.
1.11.3 Japan Ever since silk was introduced to Japan from China via Korea approximately 2000 years ago, it has held a special place in Japanese culture and
Silk
51
in the hearts of the Japanese people. Sericulture and raw silk production remained tasks essentially performed by artisans until the advent of the Meiji emperor in 1868, which marked the beginning of modern Japan. Meiji encouraged western specialists in every field (military, administrative, industrial and others) to come to Japan and help the country break with its feudal past. In 1872 a French engineer, Paul Brunnat, was invited to build and start up the first modern silk reeling plant in Japan, at Tomioka. Brunnat was accompanied by several young women from the Ardèche region who were to instruct their Japanese counterparts in the art of producing high-quality raw silk. The Tomioka reeling mill ceased its commercial activity approximately 15 years ago, but it still stands, in immaculate condition, as a historic monument. The importance of the mill at Tomioka went far beyond its immediate function of producing raw silk. The Japanese learned how to use steam generators, similar to those used in the mill, for numerous other industrial applications. The Tomioka reeling mill can rightly be considered the starting-point of Japan’s industrial revolution. The high-quality raw silk produced by this first mill and the others which soon sprang up was exported, in particular to the United States, but also to Europe. The earnings from these exports fuelled the whole of Japan’s economic and industrial development. This is another reason why Japan remains so strongly attached to silk, the starting-point of its remarkable success as a modern industrial power. The turning-point for Japanese sericulture and silk industries was the Second World War. In 1938, Japan accounted for over two-thirds of world raw silk production, with 43 000 tonnes out of a total of 54 000 tonnes. Japan exported almost 70 % of its production, mostly to the United States. The chief end-use of silk at that time was hosiery, mainly as silk stockings. Out of seven pairs of stockings sold, six were made of silk. The invention of nylon just before the war put paid to silk as a material for stockings and at the same time almost destroyed the American silk industry. Nylon also captured another market from silk, namely that for parachutes. If Japan owes so much to silk, it has also given much to silk. No other country has devoted so much time, ingenuity and money to improving silk quality. Japanese research on the mulberry, the silkworm and raw silk production techniques has been a trail-blazer since the beginning of this century. The most efficient parental strains of silkworm are Japanese and it is the Japanese who have gone furthest in attempting to diminish the impact of the labour intensive nature of sericulture and silk production. The Japanese were the first to develop an automatic reeling machine, although the principles and design were first drawn up by an American engineer living in France, Edward Serrell, who registered a patent as far back as 1886. It was also in Japan that a synthetic diet for silkworms was first developed. One of the major bottlenecks in silk production is the fact
52
Silk, mohair, cashmere and other luxury fibres
that silkworms will eat only mulberry leaves. There now exists a synthetic diet which contains about 25 % mulberry leaf extract but also soya bean meal, rice flour and various proteins. Not only does this remove the need to cultivate such large areas of mulberry plantations, but also the silkworms no longer need to be fed and raised next to the fields. The kimono still accounts for about 65 % of all uses of silk in Japan, but this proportion is diminishing steadily. The kimono is still used on ceremonial occasions, but it is increasingly rented. Young Japanese women are active and, for everyday use, the kimono is not a practical garment. On the other hand, western-style garments in silk are becoming more and more popular. Nevertheless, Japan remains a very important country in the overall silk market. It still consumes almost 20 000 tonnes of silk in various forms out of a total world production of 70 000 tonnes.
1.11.4 Brazil Silk production was introduced to Brazil by Italian immigrants in the early part of the nineteenth century, but this activity did not last very long, possibly because the farmers found it more lucrative to cultivate other crops. Sericulture really began with the first Japanese immigrants in the late 1930s. Brazilian sericulture got off to the best possible start because it was founded on the finest Japanese technology and the most stringent rearing conditions. Brazilian production reached its peak in the early 1990s, with just over 2500 tonnes, of which 95 % was exported. Japan has always been the chief outlet for Brazilian raw silk, taking between 65 % and 70 % of total exports. There are only three reeling mills left in Brazil, of which two are Japanese. The third reeling mill is part of a large Brazilian agricultural co-operative, mainly involved in producing such items as cotton, coffee, soy beans and orange juice. Brazil exports only raw and thrown silk, and a small percentage of its production is processed into fabrics in the country. Because the sector is almost totally dependent on exports, Brazilian sericulture is extremely sensitive to prices and to the economic situation of its main markets, in particular those of Japan. In 1998 and 1999, Brazilian production suffered considerably from the following factors: –
Brazil’s prices were very high compared with the low prices offered by China, given that the Brazilian real was tied to the US dollar which was gaining in value all the time. (The real has been allowed to float since late 1999.) – Japan, the main outlet, was buying fewer imports of everything, including silk from Brazil. – There was less demand from Europe.
Silk
53
The Brazilian reelers were consequently obliged to offer their farmers a much lower price for their cocoons. From just over $3 per kilo three years ago, farmers are now being offered less than $2. The result is that many of them have stopped cocoon production. It is unlikely that even with a recovery in raw silk prices these farmers will return to cocoon production because many of them have moved out of agriculture altogether.
1.11.5 Thailand There are two types of raw silk production in Thailand, white silk and native yellow silk, which is also made from Bombyx mori but is multivoltine rather than monovoltine. The first type of silk is used as warp for fabrics and garments for export, the latter essentially for domestic consumption. Most of Thailand’s production comes from multivoltine silkworms, similar to those in India. Thailand also imports raw silk from China to supplement local production. The Thai silk industry has a long history, but it came to international prominence after the Second World War, due to the efforts of the famous American, Jim Thompson, who almost single-handedly promoted it in the United States and then in Europe. If measured by international standards, Thai silk is of poor quality. It is coarse, uneven, imperfectly de-gummed and full of slubs. It is almost exclusively hand-woven, which contributes to its authentic appearance. But it has very good dyeing affinity and its very rustic quality makes it a highly desirable product. Much of Thai silk is exported ‘invisibly’, i.e. it is sold to tourists who take it out of the country. Thai silk is used for garments, furnishing fabrics and a wide range of accessories, not only clothing accessories but also such items as handbags, purses and picture frames. At the moment, Thailand is striving to introduce more bivoltine silkworm strains in order to become self-sufficient. Bivoltine silk is needed to make a strong warp which can then be filled with a weft of Thai silk.
1.11.6 South Korea The evolution of South Korea’s sericulture in the past 15 or 20 years is a case study in how increasing prosperity can cause this type of activity to decline. From being a fairly large producer (2200 tonnes in 1980), Korea is now an importer of raw silk (1256 tonnes in 1998) while its domestic production hovers around 60 tonnes. One of the causes which accelerated the decline of Korean sericulture was the Olympic Games, held in Seoul in 1988. The construction of the facilities for the games and the creation of numerous jobs in the capital attracted thousands of country people, many
54
Silk, mohair, cashmere and other luxury fibres
of them silk farmers, who never returned to the land. This move has now apparently reversed, with the economic crisis of 1997–8 sparking off a return to the land. Paradoxically, Korean cocoon production is actually increasing, but the cocoons are not used for the silk industry. The silkworm pupa, 100 % protein, goes into the manufacture of health foods, beverages and cosmetics. The speciality of the Korean silk industry today is printing. Korean printers have a reputation for being highly skilled, and their products are less expensive than their European or Japanese equivalents. Korean fabrics are especially appreciated in the United States and in Japan.
1.11.7 Other producer countries Raw silk is produced in many other countries, mostly for local use. However, if the quality of these countries’ raw materials improved, they could export the product. 1.11.7.1 Vietnam This country is a case in point. Here there is a very long sericultural tradition, but production was interrupted by many years of war. Since peace was restored to Vietnam, it has relaunched its silk production, which today stands at about 1300 tonnes. Some of the silk produced is exported to countries where the highest quality levels are not necessary, but Vietnam is making serious efforts to raise its standards so as to reach international grade 3A or 4A and thus gain access to the raw silk markets in Europe and Japan. Vietnamese raw silk is also processed into fabrics and garments through joint ventures with Japanese and Italian companies. Vietnam is a country which has considerable advantages as a potential producer/exporter of high-quality raw silk. – – – –
It has a silk tradition, giving it a big advantage over complete newcomers to the business. It has good climatic conditions. It benefits from an educated and skilled workforce. Its government has the will to continue developing sericulture.
For the time being, it seems to be that certain organisational problems are the only obstacle to progress. Because of the need to protect the farmers and guarantee a reasonable level of income from cocoons, Vietnam was not competitive during the period when raw silk prices were at their lowest. The fact that prices are increasing again is a good sign for Vietnam, providing this increase is sustainable.
Silk
55
1.11.7.2 Uzbekistan Silk production in the former Soviet Union reached about 4000 tonnes per annum in the 1980s. Most of this production came from Uzbekistan and the rest from such places as Ukraine, Tajikistan and Azerbaijan. Production was strictly controlled in terms of quantity and price, in common with all agricultural products. Trade in silk was almost entirely conducted within the Union. Since the break up of the Soviet Union, Uzbekistan has remained the largest producer in central Asia, but the quantities obtained are at present only about 1500 tonnes of raw silk per annum. Now that Uzbekistan is independent, it is seeking outlets for its production on foreign markets. However, raw silk produced in Uzbekistan is not yet of international standard. In the old Soviet system, as in many centralised economies, it was quantity, not quality, that was rewarded. The result is that the quality of Uzbek cocoons is low, although strong efforts are being made to remedy this. On the other hand, Uzbekistan is a major source of cocoons for producing silk waste and then spun silk. 1.11.7.3 Iran Apart from clothing, another application of silk is in carpets, the speciality of Iran. Production of raw silk in Iran is about 600 tonnes, used to manufacture the famous Persian rugs and carpets. Silk carpets are also manufactured in India, Turkey, Morocco and Egypt.
1.12
Silk consuming countries
As has been noted, there is no longer a sharp distinction between producer countries and consuming countries, with the possible exception of Brazil. Naturally, there are some countries, the United States for example, which have never been raw material producers but which are very large consumers. Traditional producers such as China, India, Japan and Korea both produce and consume large quantities of silk. As the Chinese people’s standard of living rises, they can be expected to consume increasing quantities of silk goods. Silk plays as important a role in Chinese traditions as it does in Japan. At present, domestic consumption of silk in China is estimated at about 28 000 tonnes. India and Japan are producers, importers and consumers. The United States has always been and still is a very large consumer of silk. Whereas this consumption was based on stockings and knitted goods,
56
Silk, mohair, cashmere and other luxury fibres
today’s consumption is in two different market segments. On the one hand, there are imports of silk fabrics from Asia and Europe and, on the other, imports of ready-made garments. These two markets represent a total value of over $2 billion.
1.12.1 Supply World raw silk production has been falling steadily since 1995 with an overall drop of about 30 %. Silk production is closely linked to the standard of living of rural populations. Silk is often described as a fibre produced by the poor for the rich to wear and it is true that the farmers who produce silk have usually been poor farmers. For a farmer to undertake or develop his production he has to be sure of a reasonable and steady income. However, silk is not a reliable product. It is subject, like all other agricultural crops, to the whims of the weather. One of the reasons for the decline in Brazilian raw silk production in 1998 was a series of meteorological setbacks: drought, followed by frost, followed by hail. Another factor of uncertainty for the farmer is the fact that demand for silk is conditioned to a certain extent by the demands of fashion. If silk is in fashion, cocoon prices will be high, but there is no guarantee that prices will remain at a high level over a long period. In certain countries, silk has been envisaged as an alternative crop to coca production (‘cocoons not cocaine’). It is a sad fact, however, that the market for drugs is more reliable than the market for cocoons.
1.12.2 Demand The overall demand for silk has also been going through a period of decline. European silk consumption, all products included, has dropped from 16 601 tonnes in 1995 to 11 658 tonnes in 1998. There are many reasons for the decline in silk consumption: –
–
Low raw-material prices which have discouraged producers and to a certain extent demoralised processors. In Europe, for example, there are no weavers specialised in weaving silk. Modern textile machines, notably weaving machines, are extremely versatile in the yarns they can process. A weaver can thus easily switch from weaving silk to weaving viscose or polyester for example. If weavers are convinced that they can earn money weaving silk they will continue to do so, but if low prices devalue the product as they have tended to do, weavers will give up. Competition from other fibres. Silk used to be considered as above competition, but many of the new microfibres offer comparable qualities in terms of feel and appearance, with the added benefit of being easier to
Silk
– –
–
–
57
maintain. In addition, these new fibres, being synthetic, are constantly being developed to give them new characteristics. Whatever its qualities, silk is not particularly convenient for the working person because of its care properties. The image of silk has been damaged not only by cheap garments which do not correspond to silk’s traditional image of luxury, but also because the silk products being manufactured in Europe no longer appeal to the consumers, who often find them old-fashioned. Fashion has to a certain extent turned away from prints, one of the major applications of silk. Printed silk ties, for example, which were a mainstay of the processing industries in Italy in particular, have lost ground in favour of jacquard ties using dyed yarns. Silk cannot be dissociated from textiles in general, and one of the trends of recent years is that people are dressing more casually. Consumers are adopting clothes in which they feel comfortable and seem less interested in dressing smartly. In many situations men no longer feel obliged to wear a tie, much less a silk tie.
Table 1.6 shows how silk consumption has evolved in Europe over the ten-year period from 1989 to 1998, not only in absolute terms but also in relation to the different product categories. The impact of protectionist legislation on imports of silk garments as well as decreasing consumer interest in these products are clearly brought out by the figures after 1994. The same trend is obvious to a slightly lesser extent in the United States as shown in Table 1.7. The United States is a major importer of silk garments which also sought to limit its imports. Table 1.6 European consumption of all silk products, 1989–98 1989 Raw materials Fabrics Garments Accessories TOTAL
1990
1991
1992
1993
1994
1995
1996
1997
1998
8 935 4 170 2 301 111
6 031 4 058 2 623 204
6 010 3 726 3 700 225
5 412 4 638 4 771 440
6 739 4 728 5 250 655
13 359 6 791 5 674 1 033
7 393 5 563 3 141 505
6 753 5 391 2 747 538
8 319 3 649 2 139 960
6 396 2 884 1 701 678
15 517
12 916
13 661
15 260
17 371
26 857
16 601
15 429
15 067
11 658
Table 1.7 US imports of silk garments (tonnes)
Garments
1994
1995
1996
1997
1998
35 111
24 583
23 888
24 476
20 519
58
Silk, mohair, cashmere and other luxury fibres
1.12.3 Possible evolution of supply and demand Today, supply and demand are roughly in balance. For example, as overall demand has declined, for a variety of reasons, China has cut back production to take this into account. Chinese production is also declining for other, socio-economic reasons. The question silk professionals are asking themselves today is ‘what will happen if there is a sudden increase in demand?’. Demand is much more volatile than supply, so the fragile balance between raw silk supplies and final consumption could be broken. It is extremely difficult to make reliable forecasts about how the situation is likely to evolve in the silk market. In 1989, when raw silk was at $51 per kilo, who would have forecast that it would have dropped to less than half that price within the space of 5 or 6 years? In the same way, to go back to the 1940s, many observers considered that nylon and other synthetic fibres would eliminate silk production. This has patently not been the case and in 1995 almost twice as much silk was produced as in 1938.
1.12.4 Production in relation to demand The fear of many western silk professionals is a shortage of raw material supply. If we take a look at the possible development of production, we can begin by stating with a fair amount of certainty that some of the traditional producers such as Japan and Korea will never be able to restart their production. The Chinese situation is less clear, because it is still too early to know whether or not China has already entered the critical point in its economic development at which sericulture enters an inevitable decline. There is every likelihood that India will continue to be a major producer for many years to come, but its needs on the domestic and export markets will have to be increasingly met by imports. If the traditional producer countries are unable to maintain or increase their production, what are the chances of new producers filling the gap? In the present state of sericultural technology, silk production is associated with countries that have abundant and cheap labour. When the other requirements for successful silk production are taken into account (e.g. soil, climate, proper technology, investment, training) there are not many countries which offer the possibility of becoming major producers. There is no lack of projects, or even of some new production on a limited scale. Indonesia, Cambodia, Laos, Myanmar, Colombia, Paraguay and other Latin American countries have the potential, but their contribution to world silk supply will take many years to reach significant proportions. Several African countries are also doing their best to introduce sericulture.
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They include the Central African Republic, Egypt, Ivory Coast, Kenya, Nigeria, Uganda, Zambia and Zimbabwe.
1.12.5 Consumption Silk has been known for over 5000 years. It has had its ups and downs throughout the ages and, in particular, it has survived the invention of synthetic fibres. Obviously, silk must be offering something other than pure performance for it to remain a desirable fibre. We can therefore imagine that it will continue to be in demand, although the real need for it is difficult to quantify. The two crucial elements in its survival will be, once again, quality and price. First of all, the quality of the raw material must be so high as to allow it to be processed on modern equipment. There are no raw silk newcomers as yet capable of providing this level of quality. Secondly, the price must be acceptable. This does not mean necessarily low, because as we have seen even at $51 per kilo silk was selling better than at $25. However, the price is not infinitely elastic. It must always be remembered that silk (0.2 % of world fibre production) is a luxury, not a necessity as are cotton (55 %), synthetic fibres, mainly polyester (40 %) or wool (about 4 %). There will always be a small number of clients prepared to pay a higher price for silk than for other fibres, but within certain limits. Consumption is likely to be influenced much more by products than by price. Although silk still benefits from a very strong image as a fibre, silk products are, at least in Europe, losing some of their appeal. Silk has so far failed to capture a sizeable market share among younger customers, if we except the sand-washed phenomenon. The demand for sand-washed silk ceased partly because it was a contradiction: the world’s most prestigious fibre was offered in the form of cheap, down-market garments. It was also a nonsense in marketing terms: how is it possible to sell silk (0.2 % of total fibre production) more cheaply than polyester (40 %)? Part of the explanation for silk’s slump in the past two or three years lies in the overall financial difficulties of some major Asian users, Korea, Japan and Thailand. As these countries slowly recover, they will presumably resume their consumption of silk products. Today, silk seems to be enjoying a partial recovery in Europe also. Designers are looking at silk again, attracted by its naturalness and its various textures. There is more and more interest in ethnic looks, which helps to explain the increasing success of Indian designs and fabrics on western markets. In addition, colour is coming back into fashion after years of minimalist blacks and greys. As silk is considered an ideal vehicle for colour, this ought to trigger increased consumption.
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Silk, mohair, cashmere and other luxury fibres
Everything considered, the signs are relatively promising for more consumption. In traditional silk countries such as China and India, improved living standards will surely lead to more people buying silk. There is not the same need to promote silk in China and India as in the west, because it is much closer to people’s everyday life and therefore more familiar. The fundamental question for the future is how to balance supply and demand, given that production is declining but consumption appears to be rising again.
1.13
What about the future?
1.13.1 Supply In every attempt to estimate the future of raw silk supply it has to be recognised that world production is declining, perhaps irrevocably. Total production in 1998 was the same as in 1990, just over 70 000 tonnes, after reaching a peak of 104 000 tonnes in 1995.The drop was particularly marked in the chief producer country, China, while the second main producer, India, is increasing its production very slowly. It has also been noted that initiating or developing raw silk production in new countries, with or without a sericultural tradition, takes a number of years, so it is vain to hope that in the near future there will be new sources of large quantities of raw silk, especially raw silk of internationally tradable quality. Does this mean that silk is doomed to disappear? If the present situation continues unchanged, the answer to this question is probably ‘yes’. The critical factor lies in the word ‘unchanged’. Silk as a fibre has always shown remarkable resilience, literally and figuratively. If it has managed to survive for over 5000 years it is because: –
–
It has succeeded in adapting to new conditions. From the initial work carried out by the Chinese and then the Japanese in domesticating the silkworm, silk production has constantly been the object of intensive research. Improved strains of mulberry, scientific selection of parental strains of silkworm and more efficient rearing methods have all contributed to the survival of silk over the centuries. When nylon was invented, silk could have disappeared completely. It did not because silk possesses a certain number of qualities that make it precious to a given segment of the overall textiles market.
There is no doubt, however, that if the present situation continues exactly as it is, there is a real threat to the future of raw silk production.
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1.13.2 Technical and scientific developments However, another scenario is now possible. The present context is not frozen in time. Many new developments are feasible in technical, scientific, industrial and commercial areas: –
–
–
Japanese researchers have for a long time been involved in trying to remove the bottlenecks in the silk production chain. One of these bottlenecks is the need to bring fresh mulberry leaves to the silkworms at regular intervals, especially in the early stages of their development. Japan has experimented with a different principle, namely bringing the silkworms to the mulberry leaves by a system of conveyor belts. Another factor which adds to the cost of silk production is the need for research. Improved strains of mulberry, scientific selection of parental strains of silkworm and more efficient rearing methods have all contributed to the survival of silk over the centuries. The Bombyx mori silkworm is capable of eating only one thing, mulberry leaves. But in Japan, and now in Italy, an artificial diet is available to feed the silkworms. This diet is based on other protein-rich ingredients as well as a certain proportion of mulberry leaves. The advantages of this type of feeding are numerous. For one thing, the area planted with mulberry trees can be much smaller, thus sparing land for food crops. Secondly, it is possible to feed the worms all the year round, as they are no longer totally dependent on freshly picked mulberry leaves. Thirdly, artificial feeding means that it is no longer necessary to rear the silkworms close to the places where the leaves are grown. It is theoretically possible to rear silkworms in any premises, provided they are clean, disinfected, temperature-controlled and have the other correct conditions.
For the time being, the possibilities of these new technologies are limited because they are expensive, but if they prove to be viable under real conditions they will be adopted in an increasing number of places and their price will inevitably start to decrease. It can therefore be expected that the silk process still leaves room for a large degree of rationalisation, without altering the natural characteristics of the silk thread. Meanwhile, science has not been standing still. One of the fields in which research is the most active is that of genetic engineering, and the silkworm is in this respect one of the organisms that interest scientists in several countries. The silkworm is an animal which presents some highly promising characteristics independently of its capacity to produce a continuous filament of textile fibre. This alone would be enough to establish its uniqueness, but there are other interesting factors.
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Silk, mohair, cashmere and other luxury fibres
The silkworm produces a fibre made of protein, i.e. it is a proteinproducing organism. If it is capable of producing the groups of proteins present in its fibroin and sericin, it ought to be capable, through genetic engineering, of producing other proteins. For some years now, scientists have been looking at the possibilities of the silkworm as an animal which could produce proteins useful to medicine. First among these is natural insulin. Diabetics are dependent on synthetic insulin which they have to take at regular intervals. It is obvious that the natural insulin, in which their bodies are deficient, would be much better. Similarly, interferon is used as a means of fighting certain types of cancer; to produce interferon naturally would be a great step forward. In January 2000, a major scientific breakthrough was achieved by research teams working together in France, Japan and the United States, who perfected the mechanism of transgenesis of the silkworm. In other words, scientists now know how to transplant certain genes onto the silkworm’s DNA. Apart from the possible applications in terms of medicine and pharmaceuticals, this technique opens up vast new horizons for the animal’s silkproducing functions. The two main lines of research which have now been made possible are: –
–
–
Enabling the silkworm to become resistant to the endemic diseases that, despite all the precautions taken, can still ravage production, especially in countries where proper conditions of hygiene are not always respected. Increasing the productivity of the silkworm. At present, Bombyx mori can produce 1600 metres of silk thread per cocoon. Research will be directed towards increasing this capacity. Finally, it ought to be possible to produce not only more quantity of silk thread but better quality, through a judicious selection of the genetic factors which enter into the production of fine silk yarn.
The development of alternative technologies, artificial diet and the results of genetic research in terms of greater productivity of the silkworm, improved disease resistance and better quality could together lead to a large-scale increase in raw silk production without planting one extra hectare of mulberry. Due to better selection of silkworm strains through genetic research, any new producing country could achieve production of good quality raw silk much more quickly than before. Obviously, the achievement of these objectives will require a considerable amount of investment, but if it is clear that the market is still capable of absorbing enough quantities of silk, it will be worth the effort. From an industrial point of view, the increasing use of computer-aided design and manufacture offer new possibilities in the realm of silk weaving.
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63
Increasingly complex designs are being realised on fabrics and it is also possible to change weave structures in the course of the process, without having to reinstall the machine each time. At this particular moment when printing is temporarily out of favour, computer-aided design allows for the production of a greater variety of jacquard fabrics. There are two areas in which the use of silk could be developed more than it is today. The first area is in blends. Silk blends easily with other fibres, especially with other natural fibres. Silk–wool, silk–cashmere, silk–cotton, silk–linen blends are easier to dye than blends of silk and synthetic fibres. In addition, these blends are mutually enhancing. Silk benefits from the specific qualities of the other fibre it is blended with, while the addition of silk adds prestige and value to the blend. While blends are already used frequently in clothing fabrics, their use could be developed and diversified, both by developing new fabrics based on fibre/fibre (‘intimate’) blends of silk with wool, linen, cotton or polyester and by the use of yarn/yarn blends. Knitted silk fabrics are another possible avenue of development. The chief advantage of knits is that they reduce one of the perceived drawbacks of silk, i.e. its tendency to crease. Silk in itself is not naturally prone to creasing, providing there is enough volume in the fabric, but its use in knits makes it virtually crease resistant without the need for chemical finishing. Silk knits have probably not been used more widely because its users expect to find a smooth, lustrous appearance as in satin, but those consumers who have experienced silk jersey are won over by its specific qualities of comfort, handle, drape and appearance. Still in the industrial context, the development of ink-jet printing will make it possible to undertake short runs with much greater flexibility, and even to offer customised silk articles. Printing a special silk scarf for promotional or commemorative purposes becomes a real possibility.
1.13.3 Spider silk So far, we have been talking almost exclusively of silkworms, in particular the Bombyx mori family, but have said almost nothing about another silk producing animal, namely the spider. The spider’s web has always held a certain fascination for people, not only because of its inherent beauty, especially when it is sprinkled with dewdrops, but also because of its strength. The spider’s capacity to produce silk has been exploited by humans in countries such as Madagascar where laces were commonly manufactured from spider silk. It has so far not been possible to domesticate the spider in the same way as the Chinese domesticated the silkworm. Anyone who has ever seen trays containing thousands of silkworms happily gorging themselves on mulberry leaves in total indifference to their neighbours will recognise that the same type of rearing is impossible for spiders. Attempts have been
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Silk, mohair, cashmere and other luxury fibres
made to extract the silk from spiders, notably in the last century, when a French priest working in Madagascar invented a tiny reeling machine designed to ‘milk’ three or four spiders of their silk. It has never been possible to extend the scope of this kind of device. Spider silk possesses some extraordinary physical properties, notably its capacity to absorb a large amount of energy without breaking and then gradually to recover its shape. This is the basic principle of the spider’s web. Scientists know how to reproduce the ‘recipe’ for making spider silk in its semi-liquid form. It is already used in certain applications such as bulletproof vests, precisely because of its energy-absorbing capacity. Until now, however, no-one has discovered how to spin this semi-liquid silk into a filament. Only the spider and Bombyx mori know how to do that. Another possible consequence of the latest discovery in terms of gene transplantation is that Bombyx mori could be modified to manufacture spider silk instead of mulberry silk. This is by no means in the realm of science fiction. Generally speaking, as soon as somebody says ‘genetically modified organism’ all sorts of fears are raised about the possible consequences if the modified genes ‘escaped’ into nature. In principle, there is no danger in the case of genetic manipulation of the silkworm, because it is, as already stated, totally captive and incapable of surviving without human intervention. So if we come back to our basic question about the future of silk production, the possibilities are not quite so bleak as they initially appear. Appendix 2 by Joyce Dalton gives further details about spider silk.
1.13.4 Developments in international trade The next few years should see an increase in silk exchanges all over the world. The ultimate objective of the World Trade Organisation (WTO) is to liberalise world trade and in particular to remove quotas. Textiles are no exception and WTO textiles are governed by a special arrangement known as the Agreement on Textiles and Clothing (ATC). The ATC is designed to assimilate the previous multilateral textile system, the Multi-Fibre Arrangement (MFA) into the WTO. This MFA was initiated in 1974 as a means of giving the textile and clothing industries of developed countries a number of years’ breathing space to enable them to adapt to competition from developing countries. MFA was in that respect an exception to the existing GATT rules. Although the initial life-span of MFA was intended to be 4 years, it was periodically renewed and instead of lasting 4 years it lasted for 21. Now that GATT has been replaced by WTO, the products covered by MFA will be ‘integrated’ into WTO, and be covered by the same rules as every other product. This period of integration is due to last until 31 December 2004, by which time all existing quotas
Silk
65
on the import of textiles and clothing should disappear. (ATC does not provide for the removal of tariffs, only for the removal of quotas). The implications for silk are considerable. Silk goods from Asia will be able to enter the European Union and the United States in unlimited quantities. In the meantime, the developing countries will have to open their frontiers to increased imports. Countries such as India and China still have high levels of import duties on the import of silk goods from the west. The level of these tariffs will inevitably have to come down. There is undoubtedly a market for western-designed silk goods in India and China. Western designer labels combined with high-quality silk garments and accessories are considered as highly desirable by the more affluent Asian consumers who already have a keen appreciation of silk. In trade terms, European manufacturers of silk goods have certain advantages over their Asian competitors. Because they are physically closer to the centres where fashion is decided (Paris, Milan, London, New York) they can react more quickly to change. In addition, they are constantly driven towards greater creativity and the best possible quality so as to appeal to a market segment that is always looking for innovation. These same features, creativity and quality, are also appreciated in Asia and there is no doubt that the western countries’ competitive advantage will not last indefinitely, as designers in Hong Kong, Korea, China and India are becoming increasingly aware of the needs of the market. For the European silk professionals it is a race to keep ahead of the competition by the exploitation of their own specific knowledge of design and marketing. Silk’s tiny share of overall textile production is at the same time an advantage and a handicap. The advantage is the exclusiveness that silk enjoys. The handicap is that the funds available for the promotion of silk are limited, compared with those available for wool and man-made fibres. Given that there is no agreement between silk producers and silk processors on the need for promotion or on the means of financing it, it may be better to talk about ‘education’ rather than promotion. The younger generation knows little or nothing about silk, unlike their mothers or grandmothers, who were much more likely to own at least one item made of the fabric. As consumers, the young have no means of distinguishing between the properties of different textile fibres if they have received no training in doing so. In today’s context, the criterion for textiles is increasingly ‘performance’. The major retailers draw up specifications running into tens of pages and their suppliers must meet these requirements, which become ever more stringent. Silk has its own specific properties, but they cannot be measured in the same way as those of man-made fibres. The obvious danger for silk is that consumers (i.e. retailers or end-users) will measure silk against these per-
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Silk, mohair, cashmere and other luxury fibres
formance criteria. If they expect silk to offer the same performance as the most recent polyester microfibres they will find it wanting. The qualities of silk are more subjective, more emotional. It is an illusion to try to evaluate silk in purely scientific or practical terms. The way colour is expressed by a silk fabric can best be appreciated by the human eye and not by a laboratory instrument. The way a silk garment feels next to the skin is quite different from the evaluation made by a system such as Kawabata, which attempts to give objective values to an essentially personal sensation. It is as much an illusion to attempt to evaluate silk in terms of ‘performance’ as it is to discuss a Van Gogh painting in terms of the chemical composition of the paints used, or to describe a Beethoven symphony in a purely mathematical way. There is no ambition for silk to replace man-made fibres in quantitative terms and there never could be. It is not fighting in the same arena, despite the persistent claims of certain synthetic fibres to be ‘silk-like’. Even in a world obsessed with performance, work-rate and productivity there is still a space available for a fibre charged with history, emotion, magic, naturalness, sensuality. This is what silk is offering and this is how it has to be judged, with its incomparable qualities which far outweigh its shortcomings. As textiles tend to become more ‘consumable’, more disposable, when consumers increasingly buy cheap garments because they can replace them easily, silk has to make a stand for quality, for durability, for value rather than price. Appreciation of silk will not happen spontaneously. There is an urgent need for consumer education, about fibres in general and silk in particular. Even among sales staff there is a serious lack of knowledge about the characteristics of a silk garment. The message that must be conveyed is that silk is different and should be cherished for its difference. For a fibre to be used uninterruptedly for over 5000 years, it must have something unique. It is up to the silk professionals to communicate this individuality and make sure that in another 5000 years silk will still reign supreme as the Queen of Fibres.
Acknowledgements A debt of gratitude is acknowledged to the authors of the following publications which, over the years, have provided such a wealth of information. The preceding chapter has drawn deeply on them to provide a wide overall picture of the world of silk as it is today. Boucher J-J, Arts et Techniques de la Soie, Paris, Editions F. Lanore, 1996 Boulnois L, La Route de la Soie, Paris, B Arthaud, 1966 Howitt F O, Bibliography of Silk, London, Hutchinson’s Scientific and Technical Publications, 1946
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Monthly Newsletter, International Silk Association, Lyon Nanavaty M, Silk: Production, Processing and Marketing, New Delhi, Wiley Eastern, 1990 Sandoz, Silk and Colour, Basle, Sandoz (Clariant) Ltd, 1988 The Silk Book, London, The Silk and Rayon Users’ Association, 1951 Vaschalde J, Les Industries de la Soierie, Que Sais-je?, 975, PUF, 1972 The following are acknowledged for permission to use their photographs. Ets. Proverbio Groupe Perrin Institut Textile de France (Lyon) International Silk Association
Bibliography Boulnois L, La Route de la Soie, Paris, B Arthaud, 1966 Feltwell J, The Story of Silk, Stroud, Alan Sutton Publishing, 1990 Hopkirk P, Foreign Devils on the Silk Road, London, Murray, 1980 Hyde N and Wolinsky C, ‘Silk; the queen of textiles’, National Geographic Magazine, January 1984 Rheinberg L, The Romance of Silk, Textile Institute, Manchester, 1992 Scott P, The Book of Silk, London, Thames & Hudson, 1993 Silk, Macclesfield, H.T. Gaddum & Co., 1989 Silk, Inter-Soie France, 1999. A comprehensive collection of samples of silk fabrics with explanations (English/French)
2 Mohair
2.1
Introduction and brief history
2.1.1 General background Mohair, the lustrous fleece of the Angora goat (Fig. 2.1), is one of the most important speciality animal fibres, detailed on the frontispiece. This is true although it represents less than 0.02 % of the total world fibre production.1 Mohair finds application in a wide range of textile end-uses, notably apparel and household textiles, but is very dependent upon fashion, as reflected in large fluctuations in price (see Fig. 2.2). Although a considerable amount of published information exists on mohair, much of the specialised knowledge required to convert the fibre into quality products remains unpublished and a closely guarded secret, even today. A comprehensive review, containing more than 1000 references, on the properties, processing and applications of mohair published by Hunter in 19932 provides a more detailed source of reference and information. For centuries, mohair has been regarded as one of the most luxurious and best quality fibres available to man. It is generally a long, straight (uncrimped but often wavy), smooth and naturally lustrous fibre which can be dyed to deep, brilliant and fast colours. The predominant natural colour of mohair is white, although there are also occasionally brown, black and pink or red varieties; such coloured fibres contain pigment (mainly melanin) in the cortex.3 The Angora goat has a single coat with good quality mohair virtually free of medullation and kemp. On average, mohair fibre diameter ranges from below 24 mm for Superfine Kids to about 40 mm for Coarse Adults. Today, mohair is largely produced in South Africa and the United States of America (Texas) but also in Turkey, Argentina, Lesotho, Australia and New Zealand. South Africa presently accounts for approximately 60 % of the world production of mohair. Table 2.1 gives the annual production of mohair worldwide since 1970.
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69
Price (US cents/kg)
2.1 Angora goats in the Pearston district of South Africa.
Year 2.2 Fluctuations in the average price (US cents/kg) of South African mohair over time.
2.1.2 General characteristics of mohair Mohair is characterised by excellent lustre, durability, elasticity, resilience, resistance to soiling, soil shedding, setting, strength, abrasion resistance, draping, moisture and perspiration absorption and release, insulation,
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Silk, mohair, cashmere and other luxury fibres
Year
South Africa
USA
Turkey
Argentina
Lesotho
Australia
New Zealand
Misc. production
Total
Table 2.1 World mohair production (million kg greasy)
1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
4.1 4.3 3.7 3.4 3.7 3.8 4.1 4.6 4.9 5.4 6.1 6.9 7.6 7.2 8.1 9.2 11.0 11.5 12.2 11.7 10.1 7.6 6.7 6.0 5.7 5.4 5.6 5.2 5.0 4.5 4.3
7.8 6.8 4.6 4.5 3.8 3.9 3.6 3.6 3.7 4.2 4.0 4.5 4.5 4.8 5.0 6.0 7.2 7.3 7.8 7.8 7.3 7.4 7.1 6.5 5.4 4.8 3.5 2.5 1.5 1.2 1.0
4.1 4.5 4.1 4.1 4.1 3.9 4.0 4.1 4.5 4.5 4.5 4.5 4.5 3.8 3.5 3.5 3.0 3.0 2.9 2.0 1.8 1.2 1.2 0.8 0.8 0.6 0.4 0.4 0.4 0.4 0.4
1.1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.9 0.6 0.6 0.4 0.5 0.4 0.4 0.4 0.3 0.25
0.9 0.9 0.8 0.6 0.6 0.6 0.6 0.4 0.5 0.5 0.6 0.6 0.6 0.7 0.7 0.8 0.8 0.8 0.7 0.6 0.6 0.5 0.4 0.4 0.4 0.5 0.5 0.4 0.4 0.4 0.5
— — — — — — — — — — — — — — 0.5 0.5 0.6 1.0 1.0 1.2 0.6 0.5 0.5 0.4 0.4 0.4 0.4 0.3 0.3 0.2 0.25
— — — — — — — — — — — — — — 0.05 0.07 0.14 0.25 0.4 0.6 0.4 0.3 0.3 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.2
— — — — — — — — — — — — — — 0.05 0.06 0.07 0.08 0.1 0.2 0.2 — — — — — — — — — —
18.0 17.5 14.2 13.6 13.2 13.2 13.3 13.7 14.6 15.6 16.2 17.5 18.2 17.6 18.9 21.1 23.8 24.9 26.1 25.1 22.0 18.4 16.8 15.0 13.3 12.4 11.0 9.4 8.2 7.2 6.9
Source: Mohair South Africa.
comfort and pleasing handle, and by low flammability, felting and pilling. Its good insulation makes mohair fabrics light-weight and warm in winter and comfortably cool in summer, which is also a function of the fabric and garment construction. Although mohair has proved extremely popular in many applications it has some limitations in certain apparel applications, because of its coarseness relative to other types of apparel fibres such as, for example, cotton. Its outstanding properties, such as resilience and durability, also make it particularly suitable for household textiles, such as upholstery fabrics, curtains and carpets.
Mohair
Cashmere Cashgora
Mohair Fine kid
15
20
71
25
Adult buck
30
35
40
Diameter (µm) From Bigham (1985)
2.3 Diameter ranges of goat fibres.4
Mohair’s lustre, smoothness, low friction, low felting and certain other properties are all related to its surface scale structure, the scales generally being thin (unpronounced or flat) and relatively long. Mohair shares many of the outstanding properties of other animal fibres, such as wool. Kettle and Wright4 gave a figure that compares the diameter ranges of various goat fibres (see Fig 2.3). Woodward5 listed the main distinguishing characteristics of mohair. Flammability Mohair has low flammability, in common with other animal fibres such as wool. When exposed to a naked flame, it burns at a low temperature and tends to shrink. The flame produces a bead-like ash, but the fibre will stop burning almost as soon as it is taken away from the flame. Durability Because mohair’s structure is pliable, it can be bent and twisted repeatedly without damage to the fibre, making it one of the world’s most durable animal fibres. Elasticity Mohair is very elastic. A typical mohair fibre can be stretched to 130 % of its normal length and will still spring back into shape. Because of the fibre’s resilience, mohair garments resist wrinkling, stretching, and bagging during wear.
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Silk, mohair, cashmere and other luxury fibres Moisture absorption
Animal fibres, such as mohair, can absorb moisture from the atmosphere readily (up to 30 % without feeling wet). Because mohair dries slowly the danger of getting a chill is reduced. Setting Mohair may be set to retain extension or deformation more readily than most other animal fibres. The fibre’s setting ability is capitalised on in the manufacture of curled-pile rugs and imitation Astrakhan rugs. Lustre Mohair’s well-known lustre is caused by its closed (unpronounced) scale formation and can be preserved or even enhanced by careful processing and dyeing. Dyeing It is possible to dye mohair brilliant colours that resist time, the elements, and hard wear. From this property has come the name ‘The Diamond Fibre’. Soiling resistance Because of its smoothness and other characteristics, mohair generally exhibits good soil resistance and desoiling. Felting Mohair has a very low tendency to felt. Light weight Mohair blends well with wool and can produce smooth yarns, enabling fabrics to be produced which are noted for coolness, such as lightweight summer fabrics. It is unsurpassed in tropical suitings, largely because it combines coolness with durability; the material is also effective when made into linings because of its good moisture absorption and drape characteristics. Length Prized as a textile fibre because of its length, mohair fibre averages about 300 mm for a full year’s growth (i.e. 25 mm per month), and 150 mm when
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73
the animals are shorn biannually. For example, exceptionally long fibres (up to 300 mm) are used to make women’s switches, doll’s hair and theatrical wigs. Various articles (quoted in Hunter2) provide general background information on mohair, its production, properties, marketing and related applications.
2.1.3 Historical background Mohair, one of the oldest fibres known to humanity and referred to in biblical times, is the fibre (i.e. the coat) from the Angora goat. The word ‘mohair’ is derived from the Arabic word ‘Mukhayar’ (also spelt Makhayar6 and Mukhaya7) stated to mean ‘best of selected fleece’,8 ‘select choice’,9 ‘silky goat-skin cloth’,10 ‘cloth of bright goat hair’7 or ‘hair cloth’.11 The Angora goat (Capra hircus aegagrus)12 is of the same species, Capra hircus, as the European milch breeds and all other breeds of domesticated (common) goat, and also a near relative of the Cashmere goat of Asia13 and certain types of Himalayan goats.14 Richterich,15 quoting Cronwright Schreiner, stated that the Angora goat descended from the genus Capra falconeri, that is thought to have had its origins in Tibet and Kashmir and is believed to be closely related to the Cashmere goat, whereas the domestic goat Capra hircus is descended from the genus Capra aegagrus, the wild goat of Persia. The Angora goat tends to thrive in areas of low rainfall and humidity.14 The Angora goat is regarded as being unique amongst goats, in that it grows fibres that do not differ widely in diameter from the primary and secondary follicles.16 The Angora goat, unlike other goats, can therefore for all practical purposes be regarded as a single-coated animal,16 and unlike cashmere goats, the Angora goat’s fibres grow continuously throughout the year,16 and the fibres are not shed annually, i.e. Angora goats do not moult. The exact origins of the Angora goat are unknown, although it is believed to have originated in the Asian Himalayas (Asia Minor)17 or Highlands of Tibet,7,9 later migrating to Ankara (known in ancient times as Ancyra)15 the province of Phrygia in Asia Minor,15 in Turkey from where the name Angora was derived,13 the Angora goat emerging in Turkey after the Middle Ages6 (at least as late as the thirteenth or fourteenth century).13 Records of the Angora goat dating back to the eleventh, twelfth and even fourteenth centuries bc have been uncovered.7 In the Bible, 1500 bc, the book of Exodus relates that the sons of Israel left Egypt ‘carrying with them goats of which the fleece [pure white goats’ wool]17 was used to make fabric to dress the altar’,7 their fleeces being woven into altar cloths and curtains for the Tabernacle.17,18,19 In Ankara, the birth of the mohair industry took place, making Turkey the first country to supply mohair as a raw material.17 This was after the
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Silk, mohair, cashmere and other luxury fibres
animals had trekked thousands of kilometres from Turkestan, the journey beginning during the thirteenth century.7 In 1550 a Dutchman found the Angora goat in Angora, Turkey and recognised the exceptional qualities of the fleece,18 and a pair of goats was sent to the Holy Roman Emperor Charles V in 1554.18,19 Ryder20 stated that the first European record of the Angora was made by Belon, and Tournefort, a French botanist (1654) in his Levant Voyage wrote that the finest goats in the world were bred in Angora (Ankara).20 Tournefort reported in 1653 that ‘the Angora goats dazzled with their whiteness and had hair as fine as silk’. The spinning of mohair in Ankara (or Ancyra, as it was then known) was undertaken by women for their families but later a closely guarded mohair industry developed in Turkey,18 with the export of unprocessed mohair being forbidden by the Sultan.18,21 In 1838, under pressure from England, the ban was lifted and to meet the demand, the Angora goat was crossed with the Kurdish goat which resulted in a decline in quality18 and a few bales were shipped to Europe. Holland used an amount of ‘Turex Gaaren’ (Turkish yarn), combining a mohair weft with a silk warp.18 In 1820 there occurred the first authentic record of the export of a few bales of mohair fibre from Asia Minor to Europe.22 In 1853 mohair spinning began in England. When mohair first reached Europe, wigmakers appreciated its qualities.6 Mohair goods were first manufactured in England in the nineteenth century,11 a cloth containing a mohair weft across a cotton warp being much in demand in 1883.11 The first Angora goats to leave Turkey went to South Africa in 1838.18,22 During the journey, involving a cargo of 12 bucks and a doe, the latter gave birth to a male kid.18 Not until 1865 did mohair exports from the Cape to the United Kingdom reach any magnitude.23 Angora goats (seven does and two bucks)9 arrived in the USA around 1849.6 Angoras were introduced into Australia during the 1850s and 1860s24 (although some state the date to be as early as 1832),13 but received little interest; a new ‘mohair industry’ was established in about 1970.24 Angora goats were introduced to Britain in 1881.24
2.2
Chemical and physical fibre properties
2.2.1 Single fibre tensile properties Single fibre tensile properties are important from a textile point of view, fibre strength playing an important role in fibre breakage during mechanical processing, including spinning, yarn strength, fabric manufacturing and in the ultimate strength of the fabric. Generally, in the case of animal fibres, fibre strength increases almost linearly with the fibre cross-sectional area,
Mohair
75
Table 2.2 Average values for some tensile properties of wool and mohair*26 Property
Mean
SD
CV %
Range
n
Wool** Fibre diameter (mm) Linear density (dtex) Staple crimp (cm-1) Resistance to compression (mm) Bulk/diameter ratio (mm/mm) Tenacity (cN/tex) Initial modulus (cN/tex) Extension at break (%)
22.7 6.6 4.2 17.5 0.79 12.7 290 37.0
3.3 2.0 1.2 2.8 0.19 0.9 27 2.6
15 30 27 16 24 7 9 7
18.1–33.1 3.5–12.8 1.9–6.5 13.6–24.7 0.41–1.29 10.9–15.0 230–392 31.5–41.2
56 56 56 56 56 56 56 56
Mohair Fibre diameter (mm) Linear density (dtex) Tenacity (cN/tex) Initial modulus (cN/tex) Extension at break (%)
32.1 11.9 16.7 407 42.7
5.8 3.3 0.7 13 2.1
18 28 4 3 5
20.7–44.3 5.8–20.1 14.6–18.1 384–430 38.0–45.8
29 29 29 29 29
* 20 mm test length and rate of extension 20 mm/min. ** Low crimp wool excluded.
more particularly the cross-sectional area of the thinnest (i.e. weakest) place along the fibre. The fibre strength divided by the fibre cross-sectional area, preferably at the thinnest place, is therefore almost constant for a particular type of fibre. Meredith25 found that mohair and camel hair have a greater yield stress than the coarsest wool and about the same initial Young’s modulus. Smuts et al.26 found that mohair generally had a higher single fibre tenacity, initial modulus and extension at break than wool of the same diameter, and the mohair tensile characteristics were fairly constant over the whole range of diameters, probably because of the absence of crimp and variations in crimp and any associated fibre characteristics. Lustre wools (e.g. Lincoln and Buenos Aires) had tenacities and initial moduli close to those of mohair.26 Table 2.2 (as given by Smuts et al.) shows average values for some tensile properties of wool and mohair. Table 2.3 is reproduced from the report by Smuts and Hunter.27
2.2.2 Fibre bundle tenacity properties Hunter and Smuts28 found that both bundle and single fibre tenacity were independent of mohair fineness, although the initial modulus increased slightly with an increase in fibre diameter. They gave a table (Table 2.4) of typical tensile properties for mohair.
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Silk, mohair, cashmere and other luxury fibres
Table 2.3 Effect of gauge length on single fibre tensile values27 Gauge length (mm) 10 40 or 50 100
Extension at break (%)
Tenacity (cN/tex)
Mohair
Heterotype
Kemp
Mohair
Heterotype
Kemp
47.9 38.3 30.2
— — 26.2
46.6 34.9 21.8
17.9 15.5 12.6
— — 10.8
14.8 12.4 8.8
Table 2.4 Typical tensile properties of mohair28 Property
Bundle test*
Single fibre test
Tenacity (cN/tex) Extension (%) Initial modulus (cN/tex)
14.0 14.6** —
16.7 43.0 407
* Leather linings were used and the tenacity values were multiplied by a correction factor of 1.16. ** The bundle test is not considered to give reliable extension values.
2.2.3 Fibre bending stiffness King29 found that the static bending and extension moduli of mohair fibres were similar and of the order of 308 cN/tex. They also found that the medullae of kemp fibres differed in optical density, indicating different cell densities; this affected the bending but not the extension moduli. Two types of kemp, one with a filled medulla and the other with a virtually empty medulla, were investigated. For the latter, the bending and extension moduli of the kemp were similar at about 77 cN/tex, whereas the filled medullae gave a bending modulus of about 365 cN/tex, which was higher than that found for mohair.29 The extension moduli of the two types of kemp fibres were similar, indicating that any material in the medullae did not contribute to the tensile properties of the fibre, confirming the results of Hunter and Kruger.30,31
2.2.4 Fibre friction As in the case of wool, mohair fibres have a lower friction when rubbed from the root to the tip (i.e. with the scales) than when rubbed in the oppo-
Mohair
77
Table 2.5 Fibre frictional properties35 Fibre
m2
m1
m2 - m1
m2 + m1
Wool Mohair Human hair
0.40 0.23 0.19
0.22 0.15 0.09
0.18 0.08 0.10
0.66 0.38 0.28
(all measured in distilled water against felt) m1 with-scale. m2 against-scale.
site direction (i.e. from tip to root, termed against-scale). The low againstscale friction of mohair, relative to wool, which is one of its distinguishing features, can be largely attributed to its relatively smooth (unpronounced) scale structure. It is this characteristic which gives mohair its low felting propensity. Mohair has a very small directional friction effect (DFE), due to the extremely easy deformation of the thin distal edges in mohair and also to the absence of tilted outer surfaces and other high asperities. The against-scale (m2) to with-scale (m1) friction ratio of mohair is about 1.1 compared to about 1.8 for merino wool.32 The ‘scaliness’ ((m2 - m1) ¥ 100 %/m1) of mohair, measured dry, is about 5 compared to about 60 for a fine merino wool (Speakman and Stott33 quoted by Onions32). When measured wet the respective values are about 16 for mohair and 120 for merino wool. Frishman et al., quoted by Harris,35 gave a comparative table (Table 2.5) for fibre friction.
2.2.5 Moisture related properties Although mohair, as does wool, can absorb large quantities of moisture (up to about 30 %) without feeling wet or damp, its surface is naturally water repellent, largely due to the presence of a strongly bound thin surface layer of waxy or lipid material which requires strong chemical action to remove it. The moisture-related properties of textile fibres are extremely important as they play a crucial role in the comfort of the fibre and in its behaviour during wet treatments and drying. Temperature and moisture also play an important role in the visco-elastic properties of wool and mohair. Speakman36 published a table (Table 2.6) illustrating the absorption and desorption of moisture by wool and mohair at different relative humidities. Watt presented a comparative table (Table 2.7) of equilibrium water content (regain) for seven keratins including mohair.
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Silk, mohair, cashmere and other luxury fibres
Table 2.6 The absorption and desorption of moisture by wool and mohair at different relative humidities36 Percentage increase in weight of wool Relative humidity %
Geelong 80s merino
Southdown
Oxford Down
Leicester
Wensleydale
Mohair
7.0 25.0 34.2 49.8 63.3 75.0 92.5 100.0
3.40 6.96 8.41 11.22 13.97 16.69 23.81 33.3
3.37 6.90 8.62 11.48 14.19 17.03 24.17 32.9
3.17 7.03 8.79 11.68 14.41 17.30 24.49 35.3
3.40 6.96 8.54 11.44 14.46 17.43 24.59 32.9
3.46 7.01 8.67 11.59 14.51 17.44 24.90 33.9
3.41 6.93 8.64 11.51 14.41 17.33 24.24 31.8
25.98 19.02 16.28 13.39 10.58 4.79
26.13 19.16 16.46 13.46 10.63 4.76
25.82 18.91 16.26 13.46 10.68 4.87
Desorption 92.5 75.0 63.3 48.7 34.2 7.0
24.70 18.69 16.12 13.36 10.57 4.77
25.70 18.79 16.16 13.38 10.55 4.73
26.33 19.05 16.43 13.47 10.64 4.83
Table 2.7 Equilibrium water contents for seven keratins at 35 °C (in percentages) Relative humidity
Merino wool
Corriedale wool
Lincoln wool
Mohair
Monkey hair
Horse hair
Rhino horn
5 10 20 35 50 65 80 90 95 100
2.6 3.9 5.9 8.6 11.3 14.4 18.6 23.6 27.7 34.2
2.5 4.0 6.1 9.0 11.8 15.0 19.6 25.0 28.2 33.5
2.5 4.0 6.1 9.0 11.5 14.5 19.2 25.4 29.7 36.0
2.5 3.7 5.7 8.3 10.7 13.7 17.5 22.2 26.1 32.3
2.2 3.3 5.1 7.5 10.0 12.4 16.3 21.4 24.9 30.0
2.3 3.5 5.5 7.9 10.7 13.8 18.2 22.7 26.9 32.8
2.5 3.8 5.6 8.4 11.4 14.8 20.1 28.0 35.5 49.0
Source: Watt.
Mohair
79
2.2.6 Scale pattern Mohair, wool and hair are covered by a layer of sheet-like hardened cuticle cells (epidermal scales) which overlap each other, with their exposed edges toward the tip of the fibre. The cuticle plays an important role for the whole fibre because it is, on the one hand, exposed to environmental influences and, on the other hand, responsible for the surface properties of the fibre. The cuticle or scale structure is largely responsible for the felting behaviour of wool and mohair and also for the lustre of mohair. Although, under a microscope, mohair is similar in appearance to wool, the epidermal scales (cuticle scales) of mohair are only faintly visible. The cuticle scales are quite thin and flat, generally being less than about 0.6 mm in thickness and hardly overlap.37 They are anchored much more closely to the body of the fibre,1,38,39,40 i.e. they lie near to the stem or are piled more tightly upon one another,41 giving the fibre a very lustrous and smooth appearance. In general, mohair has a relatively low scale frequency, with a wide distance between the cuticle scale margins. The number of scales per 100 mm is generally of the order of 5 compared with between 9 and 11 in fine wools, with the scale lengths ranging from 18 to 22 mm. In the case of kemp, the number of scales per 100 mm is 10 or more, which is twice that for mohair; and they are arranged in a coronal or ring pattern, with smooth margins.1 The scale structure described above is responsible for mohair’s smooth handle, high lustre, low against-scale friction and very low felting propensity. The width to length ratio of mohair fibre scales is of the order 2.20 Ryder and Gabra-Sanders42 found that the width to length (W/L) ratios of scales from various goat fibres showed a clear sequence from the wild ancestor (Capra aegagrus) to mohair. They defined the scale width as equal to the fibre diameter. Indications were that the W/L ratio was independent of fibre diameter.
2.2.7 Medullation and kemp Medullated fibres in mohair can be a source of problems in many end-uses when they differ in appearance from the rest of the fibres which are not medullated. They are characterised by having a central canal (medulla) containing cell residues and air pockets, running in either a continuous or fragmented form along their length (Fig. 2.4). The term ‘kemp’ is probably more familiar, but this traditionally refers to the more problematic and extreme form of medullated fibre where the medulla is clearly visible to the naked eye. The main problems associated with the presence of kemp (perhaps more correctly termed ‘objectionable’ medullated fibres) are their chalky white appearance, their lighter appearance after dyeing and, to a lesser extent, their effect on handle, stiffness and prickliness.2,50,253 The chalky
80
Silk, mohair, cashmere and other luxury fibres (a)
(b)
(c)
(d)
2.4 Classification of medullae14: (a) unbroken lattice (wide); (b) simple unbroken; (c) interrupted; (d) fragmented.
2.5 Kemp.46
2.6 Mohair.46
Mohair
81
white appearance of kemp is largely caused by the decreased length of the light path through the dyed fibre material and light refraction at the fibre/medulla interface and within the hollow network of cells (aerian vesicles). This, and not poor dyeability, is considered to be the main cause of the different appearance of kemp fibres after dyeing.43,44,45 Generally, the presence of even a small amount of kemp in a high quality mohair may have a pronounced adverse effect on its value. Higher grades of mohair are largely free from kemp and medullated fibres, the kemp content being well below 1 % in well-bred mohair. Those medullated fibres that contain a discontinuous (fragmented or broken) medulla are generally referred to as heterotype or ‘gare’ fibres.47,48 Heterotype fibres are therefore medullated (or ‘kemp-like’) in certain sections and ‘normal’ (i.e. solid) in others. Kemp is usually straight, and oval in cross-section. Of all the types of medullated fibres that occur in both wool and mohair, those collectively called kemp, tending to have a relatively large medulla and to be relatively coarse, are the most visible and unwanted in the final product. Kemp occurs as short kemp, long kemp and heterotype fibres. The ‘short kemp’ is generally the most common, being short, chalky white, medullated and pointed at each end when it has fallen out and has not been shorn off. Small portions of multiple medullae are also occasionally present in mohair fibres.49 Kemp or ‘objectionable medullated fibres’ are generally much coarser than the parent population (on average 1.8 times coarser than the mean fibre diameter of the parent population).50 Hunter46,51 gave an electron microscope photograph of kemp, illustrating its surface appearance (Fig 2.5) compared to that of mohair (Fig 2.6).
2.2.8 Chemical and physical nature of the medulla The medulla consists of a hollow network of cell walls (Fig 2.7) (aerian vesicles), filled with air, which are cytoplasmic remnants of the basal layer cells (Clement et al., quoted in Powell).45 The chemical composition of medullary cell residues appears to be different from that of the cortical cells,53,54 the medullary cells containing little if any sulphur.55 Swart56 showed that the amino acid composition of kemp was different from that of adult mohair and that the medullated fibres contained more b-keratose but less gkeratose than true mohair. It was reported (Mercer57 quoted by Tucker et al.58) that the proteins of the medullary cells are of a non-keratin type and therefore exhibit different chemical behaviour to the keratins. They are easily broken down by proteolytic enzymes but have a high alkali stability (Kusch and Stephani,59 quoted by Tucker et al.58). The levels of the amino acids citrulline, glutamic, lysine and leucine, in the medullary cells are higher than those present in the whole fibre whereas glycine, serine, proline,
82
Silk, mohair, cashmere and other luxury fibres
2.7 Cross-sections and longitudinal sections of medullated fibres illustrating the cellular nature of the medullae.
threonine and particularly cystine are lower (Bradbury and O’Shea,60 Harding and Rogers61 quoted by Tucker et al.58).
2.2.9 Fibre chemical, morphological and related structure and properties The reader is referred to excellent and detailed reviews of this subject by Zahn,40,63 Spei and Holzem64 and Tucker et al.58,65. Zahn et al.66 earlier reviewed the biological composite structure of wool, including mohair. All animal fibres, except silk, contain the same chemical substance, a protein called keratin. Keratin can be regarded as a long fibrous composite, comprising crystalline, relatively water impenetrable microfibrils, lying parallel to the fibre axis and embedded in an amorphous, water penetrable matrix.67 Thus wool and mohair fall into the class of protein materials known as keratins, characterised by their long filament-like molecules and insolubility in dilute acids and alkalis. They generally have a high sulphur content when compared with other proteins.68 All mammalian keratin fibres contain three main protein fractions,69 termed low-sulphur, high-sulphur and high-tyrosine proteins, with the low-sulphur proteins generally representing the largest proportion. All animal fibres contain approximately 3 to 4 % sulphur, largely as cystine. The mohair fibre generally consists of a cortex (cortical cells), the solid and main part or bulk of the fibre, which is predominantly ortho-cortex (cortical cells), and epidermis (cuticle cells) of
Mohair
83
Fine fibre
Endocuticle Exocuticle Epicuticle Tyrosin rich protein
Cuticle
Inter microfibrile material
Protein
Matrix
Right hand helix
Microfibrile
Cell membrane complex Coarse fibre Orthocortex
2.8 Structure of a mohair (Adult) fibre.73
numerous overlapping scales.70 Sometimes there is also a continuous or discontinuous medulla present. The cuticle scales form a protective covering for the cortex and consist of three layers, epicuticle, exocuticle and endocuticle (see Fig 2.8). Each cuticle scale is enveloped by a thin semipermeable71,72 membrane called the epicuticle, which comprises protein and lipid. Smith73 depicted the structure of a mohair fibre as shown in Fig 2.8.73 (For further details and discussion of the physical and chemical composition of mohair see Appendix 3.)
2.2.10 Fibre identification and blend analysis It is important, for such purposes as labelling and Mark Certification to distinguish between mohair and other animal fibres and to quantify the composition of a sample (be it raw fibre, top, yarn or fabric) which reportedly contains mohair in any proportion, particularly where the mohair is blended with another animal fibre, such as wool. It is hardly surprising, therefore, that considerable research effort has been directed over the years, but more particularly since the early 1980s, towards developing reliable methods for distinguishing between mohair and other animal fibres. Wilkinson,99 in summarising the papers dealing with fibre identification, presented at the
84
Silk, mohair, cashmere and other luxury fibres
Table 2.8 Fibre identification tools and targets Tool
Target
1. Microscopy; light transmission and scanning electron, image analysis
fibre dimensions1,2 ellipticity1,2 surface features1,2 pigment distribution1 medullation1 cortical segmentation1 protein composition1,2 external and internal1,2 lipids
2. Chromatography, electrophoresis 3. High pressure liquid chromatography, gas chromatography 4. DNA hybridisation 1 2
cell nuclear remnants1,2
First International Symposium on Speciality Animal Fibres. Second International Symposium on Speciality Animal Fibres (see ref. 99).
Second International Symposium on Speciality Animal Fibres in Aachen in 1990, pointed out that the list of possible techniques was quite long, but could be shortened if restricted to rapid, inexpensive and internationally accepted methods; shortened further if restricted to fibre mixtures of unknown origin in which suspect contaminants are in low proportion; shortened even further if the fibres or fabrics have been subject to pretreatments; and probably obliterated if all the restrictions are imposed. Some tools and targets are listed in Table 2.8.99 Figure 2.9 shows scanning electron micrographs of fibres showing scale structures of wool fibres (a and b) and of mohair fibres (c and d). (All magnification values here refer to original magnification.) Figure 2.10 shows the scale height (h) or thickness of a fibre. Laker and Wortmann34 and Greaves100 have reviewed the various methods of fibre identification and the quantitative analysis of fibre blends, while Hamlyn et al.101 listed the methods (Table 2.9) that have been proposed for the qualitative and quantitative analysis of keratin fibres. A similar list has been given by McCarthy.12 The first methods relied upon the use of a light microscope to examine the surface scale appearance (prominence, pattern and frequency) of the fibre and then to classify the fibre as mohair or wool depending upon a subjective assessment of the nature, frequency and prominence of the scales and they required an experienced operator. Eventually, they led to modern scanning electron microscopic (SEM) methods, as well as image analysis.102,103 In recent years the scale height method, measured by SEM, has found the widest application. In one of the first studies (1985) relevant to the use of the scale height method for differentiating between mohair and wool,
Mohair
85
(c)
(a)
(d)
(b) 2.9 Scanning electron micrographs of fibres showing wool and mohair fibres: (a) wool scale structures 1400¥; (b) wool scale structures 3300¥; (c) mohair scale structures 1400¥; (d) mohair scale structures 3300¥.106–107
2.10 Scale height (thickness), h, of a fibre.
86
Silk, mohair, cashmere and other luxury fibres Table 2.9 Methods proposed for the analysis of keratin fibres101 Amino acid analysis Scale-height measurement Image analysis PAGE Analysis of extracted proteins Internal- and external-lipid analysis DNA Fibre-profiling
Oster and Sikorski108 showed that the scale thickness of merino wool is of the order of 1 mm and that of mohair of the order of 0.4 mm. Dobb et al.109 were among the earliest to observe that differences in scale height (distal edge) measured by electron microscopy could be used to distinguish between wool and mohair. Nevertheless, it was not until 1980 that Kusch et al.110 used the difference in cuticular scale height, as measured by SEM, to distinguish between wool and goat hair. Kusch and co-workers were amongst the first to propose and use the SEM-measured scale heights to distinguish between wool and various animal fibres, for example mohair, and to quantify the blend composition of such fibres; their work is detailed by Hunter.2 The scale thicknesses were measured at a magnification of 25 000 and the fibre diameter at a magnification of 1000, fibres with a scale height greater than 0.6 mm being classified as wool and those with a scale height smaller than 0.5 mm as mohair.111,112 In essence, the SEM method (see International Wool Textile Organisation Draft Method – 1996 E) is based upon the fact that mohair scales are generally, but not always thinner than those of wool, having an average thickness (height) of around 0.4 to 0.5 mm (0.2 to 0.4 mm),113 while those of wool, including lustre wools (such as Buenos Aires), have an average thickness (height) of around 0.8–1.0 mm (0.6–1.1 mm)108,109,113,114,115,116,117 (see Fig. 2.11). Wortmann and Arns116,118,119 concluded that the scale heights of speciality animal fibres rarely exceed 0.5 mm (and are generally 0.2 to 0.4 mm)116 while those of wool rarely fall below 0.5 mm (and are generally 0.6 to 1.1 mm,116 rare occurrences are of little consequence in the application of the scale height method for analytical purposes). They found the scale height for the samples of wool they tested ranged from 0.4 to over 1.0 mm and that of the mohair samples they tested ranged from just over 0.1 to just over 0.5 mm. Phan et al. have also carried out SEM analyses.120 Recent papers121,122,123 discuss, and express opposing views on, the role of chemical treatments on the accuracy of the scale height method of blend analysis. A system of fibre classification (Fig 2.11) according to the SEM method was given by Phan et al.117. Schnabel et al.,124 Wortmann et al.125 and Hermann et al.126 concluded that both the weighted discriminant analysis and the
Mohair
87
Pure fibre sample mean diameter ≈ 16 –19mm
< 16mm
≈ 0.4mm
≈6–8 cashmere
≈ 0.4mm
≈ 0.8mm
cashmere, vicuna
super fine wool
mean scale frequency >9 vicuna
typical scale patterns
Angora rabbit hair GROUP I
> 19mm
Iranian cashmere, wool yak hair, camel hair cashgora mean scale height
super fine wool, cashmere, vicuna
≈ 0.8mm
Iranian cashmere, yak hair, camel hair cashgora
Iranian cashmere, camel hair, cashgora
wool
yak hair
mean scale height ≈ 0.4mm
mean scale frequency >9
≈6–8
mohair, wool llama, alpaca
≈ 0.8mm
mohair llama, alpaca
≈6–8 mohair
wool
mean scale frequency/ scale patterns >9 llama, alpaca
scale patterns
Iranian cashmere
camel hair GROUP II
cashgora GROUP III
2.11 Classifying and characterising of luxury fibres by means of scanning electron micrograph.117
cluster analysis may be applied as an approximate method for evaluating fibre blends, such as wool and mohair. Baxter127 reported that a combination of Optical Fibre Diameter Analyser (OFDA) measured parameters enabled the composition of wool and mohair blends to be determined. In more recent years the application of DNA techniques for distinguishing between different animal fibres has received considerable attention;2,104,128,129 the DNA extracted from the fibre shafts, with about 20 mg of fibre sample, is adequate. A prerequisite for fibre profiling is the identification of short DNA sequences unique to each species.130 Once located, complementary DNA sequences (oligonucleotides) can be constructed which, under carefully controlled conditions, hybridise to the target DNA molecule, giving a positive signal, confirming the presence of a particular fibre type.130 Conventional DNA hybridisation analysis is carried out using a single dot-blot technique, but cannot be applied to wet processed fibre since the latter contains much less DNA. For such materials, in vitro DNA amplification104 technology polymerase chain reaction (PCR) can be applied.104,129,131 This cannot, however, be used as a quantification test, but only for showing the presence of a particular fibre, i.e. adulteration. A combination of the projection microscope technique and DNA investigation has been advocated.130 The rapid and cost-effective application of the DNA
88
Silk, mohair, cashmere and other luxury fibres
2.12 Amplification of target DNA using the polymerase chain reaction (PCR).104
technique for quantitative analysis of animal fibre blends remains a challenge, particularly in the case of wet processed yarns and fabrics.104,129 The amplification of target DNA using the polymerase chain reaction is shown in Fig. 2.12.
2.3
Fibre production and early processing
2.3.1 Fibre growth and production Mohair grows at about 25 mm each month, irrespective of age, and Angora goats are generally shorn twice a year in South Africa and the USA and once a year in Turkey and Lesotho, although high levels of nutrition could necessitate more frequent shearing.3,8 Young and Adult goats produce about 2 to 2.5 kg of greasy mohair every 6 months, and rams generally produce considerably more,132,133 and coarser hair than ewes.3 In the case of Kids, the fleece barely weighs 1 kg at the first shearing and is generally less than 2 kg at the age of one year134 (i.e. at the second shearing). It appears that the Angora goat is very efficient in converting feed into fibre,135 and is more effective than woolled sheep;3,136 the latter are more effective in converting feed into body mass. Greasy fleece mass has a hereditability of 0.4, i.e. 40 % is controlled genetically, although another study137 suggested 0.22; the remainder is due
Mohair
89
Table 2.10 Curvature and diameter values of several different wool fibres140 Fibre
White Alpaca Fawn Alpaca Lincoln Mohair Cashmere Southdown Corriedale
Mean curvature (cm-1)
Mean diameter (mm)
Wet
Dry
2.0 1.2 2.4 1.2 6.8 18.8 10.0
8.4 6.0 5.0 1.4 12.7 32.0 16.4
30.2 40.0 36.0 43.6 13.8 23.8 29.7
to (factors such as feed. Staple length has a hereditability factor of 0.8.20,138 Fibre diameter has a hereditability of 0.2138, (another study found 0.3)139; it is very sensitive to changes in nutrition and to the age of the animal. Mohair does not have crimp in the true sense of the word but exhibits waviness or curl. Curvature values for mohair and other animal fibres are given in Table 2.10.140,141
2.3.2 Effect of Angora goat age on fibre production According to Van Der Westhuysen et al.3,142,143 the age of the goat is probably the most important factor determining the quantity and quality of mohair produced. Mohair production reaches an economic peak at approximately 18 to 24 months of age because at this stage the production of the finest and most valuable fibre is at its highest.3 Kids have a birth coat of fibres that grow mainly from the primary follicles, those being the follicles which produce kemp and medullated fibres.144 From about three to six months the goats shed their birth coat (‘mother hair’) as the fibres grow increasingly from the secondary follicles which produce the finer hairs.144,145 Fibre production increases from birth, reaching a maximum fleece mass at an age of between approximately three and four years.3,8,146,147 With age the fibre diameter increases, reaching a maximum at approximately five years.3,146,147,148,149 Duerden and Spencer150 and Venter151 found the mohair fibres were finer towards the tips, due to the fact that the fibres become coarser as the goat ages.3,146,148 Kids nowadays produce mohair with an average diameter of about 26.5 mm at their first shearing, approximately 28 mm at the age of one year (second shearing), and 31 mm for Young Goats at 18 months of age (third
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Silk, mohair, cashmere and other luxury fibres
Fibre diameter Body mass
Percentage of maximum
Staple length
Mohair mass
kg mohair/ kg body mass
Age (years)
2.13 The effect of age on fleece and fibre characteristics in the Angora goat.3
shearing), while Adult Goats produce mohair varying in fibre diameter from about 34 to 40 mm. In general, mohair obtained from the first two shearings (i.e. at 6 and 12 months) is classified as from kids, that obtained from the third (and also sometimes from the fourth) shearing (i.e. at 18 months and sometimes at 24 months) is classified as from Young Goats and after that (i.e. from the fourth or fifth shearing or from the age of 24 or 30 months) the hair is classified as Adults. Generally mohair from Kids is finer than 30 mm, from Young Goats finer than 34 mm while from Adults coarser than 34 mm. Goats are classed as young goats up to the age of 3 years in Turkey but only up to 18 months in South Africa.152 Van Der Westhuysen et al.3,143 gave Fig. 2.13 illustrating the effect of goat age on fleece and fibre characteristics.
2.3.3 Effect of nutrition, season and lactation on fibres and fibre production Mohair growth shows a seasonal effect, probably mainly as a result of changes in the day length, even when the goats are kept on a constant diet,166 fibre production tending to increase with increasing temperature and length of day;136 lactation and low nutrition have the opposite effect. More fibre is grown in summer than in winter; nutrition affects the seasonal growth cycle but cannot eliminate it entirely. Angora goats can grow up to 1.7 times more mohair in summer than in winter.20,153,154 Both in South
Mohair
91
Africa and in Texas the winter mohair tends to be shorter, finer and less ‘kempy’.166 Reproduction generally suppresses the rate of mohair growth and the demands of lactation are more pronounced than are those of pregnancy.3 Body mass, mohair production and fibre diameter generally decrease during lactation. Adult body mass is correlated with mohair production and fibre diameter.3 As happens to wool, the tips of the mohair fibres covering the back of the animal are damaged by sunlight or weathering, especially during the summer months.1 This damage has an influence on the dyeing property of the affected fibre part.1,38
2.3.4 Secondary and primary follicles The amount and type of hair produced by an Angora goat depends upon the number of follicles present in the skin, namely primary (P) and secondary (S),145 and their ratio (S/P), the Angora having a skin follicle structure very similar to that of sheep, with an S/P ratio of between 7 and 12.155 It is generally thought that all primary follicles are producing fibre when the kid is born, the fibres that make up the birth coat being very coarse, although the primaries do subsequently produce finer fibres.145 The secondary follicles show little sign of development in the first week of the kid’s life, but during the next two weeks follicle maturity is very rapid. By the time a well fed kid is 6 to 8 weeks old, 75 to 80 % of its ultimate number of follicles may be producing fibres. Research results have emphasised the important relationship between nutrition and follicle numbers and hence the effect of nutrition on fibre production. Since there are many times more fine secondary follicles than primaries, it follows that the level of nutrition of the doe late in pregnancy (i.e. when the secondary follicles are developing in the foetus) and of the kid during its first ten months of life (i.e. when the secondary follicles are maturing and coming into production) are critical. If insufficient food is provided at these stages, the lifetime fibre production will be affected.145 Table 2.11 shows some average values and ranges of various mohair properties.
2.3.5 Mohair grease and other fleece constituents The fleece of the Angora goat, when shorn, contains natural and applied impurities; usually a total of 10 to 20 % of non-fibre is present. The sweat or suint, the water soluble component and grease (wax) combined are termed yolk. The grease (wax) is secreted by the sebaceous glands and the sweat (suint) by the sudoriferous glands. Other natural impurities contained in mohair include sand and dust (i.e. inorganic matter), vegetable matter (e.g. burr, grass, seed) and moisture. Applied impurities include branding
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Silk, mohair, cashmere and other luxury fibres Table 2.11 Some average values and ranges of various mohair properties157 Property
Range
Average value
Diameter (mm) CV (%) Staple length (mm) Medullation (%) Curls per 10 cm VM (%) Grease (%) Suint (%) pH of suint Scoured yield (%) Compressibility (mm)
23–45 20–33 84–137 0.3–2.8 2.8–6.6 0.1–1.7 2.9–8.0 1.8–4.2 3.3–6.2 77–93 10–13
33 25 109 1.0 4.5 0.3 4.6 2.7 5.3 86 11
Table 2.12 The composition of raw whole fleeces58 Fibre
Moisture (%)
Grease (%)
Water solubles (%)
Wool Mohair Australian cashmere Chinese cashmere Cashgora Llama Alpaca Camel Yak
11.0–11.7 12.0–14.4 10.7–13.9 11.1–12.9 13.2 12.0 10.9–14.4 9.9 10.4
9.5–27.0 1.2–8.0 0.7–2.5 5.0–7.2 1.2–2.8 2.8 2.8–3.9 0.5–1.1 12.3
3.9–7.1 1.8–4.2 1.2–3.5 2.3–3.0 0.6 — 0.6–2.4 — —
fluids and dipping compounds. Generally, mohair contains considerably less grease than wool (4 to 6 % on average, compared with an average of about 15 % for wool). Because the yolk content of mohair is lower than that of wool, shearers are said to have to change combs and cutters more often than with wool. Tucker et al.58 presented the data for various speciality fibres that is shown in Table 2.12. Mohair, by virtue of its open fleece structure on the goat, is more exposed to weathering than is wool and its wax is more oxidised than that of wool,189 making it more difficult to remove during scouring.143 Ilse190 compared the composition of mohair, karakul and merino wool waxes as shown in Table 2.13 and concluded that the mohair and karakul waxes had the usual merino wax components in surprisingly similar proportions.
Mohair
93
Table 2.13 Characteristics of the waxes190 Merino wax Wax content of the fleece (%) Saponification value (mg KOH/g) Acid value Hydroxyl value Iodine value Acids (%) Unsaponifiable material (%)
Mohair wax
14–16 92–102 4 54 15–30 49 51
Karakul wax
5
3
128 14 57 36 55 45
110 9 58 56 50 50
Table 2.14 Chemical constants for mohair grease192 Characteristics
Value
Literature
Saponification value Acid value Iodine value Percentage acids Percentage unsaponifiable fraction Ester value
126–135 14.6 14.8 54 46 117
128 14.0 36 55 45 114
Mohair from Kids and Young Goats contains more grease than that from Adults, with the grease content higher in winter than in summer191,192 and also higher towards the root (e.g. tip = 2.0 %, middle = 4.6 % and root = 6.0 %). Uys, quoted by Kriel,192 found an average grease content of 4.5 % for summer hair and 5.8 % for the winter hair, with a melting point of 39 °C. He found the acid value to be 14.6 compared with a published value of 14. The unsaponifiable fraction was 46 %. Kriel192 published values (given in Table 2.14) for the chemical constants for mohair grease.
2.3.6 Objective measurement The textile processing performance, applications and general quality and therefore value and price of mohair are largely determined by the characteristics of the raw (greasy) mohair. It is therefore hardly surprising that considerable effort has been directed over the years towards the objective (i.e. instrumental) measurement of these characteristics, as opposed to the subjective techniques traditionally used. Today, characteristics such as fibre diameter and yield can be, and often are, measured objectively with high accuracy.
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Silk, mohair, cashmere and other luxury fibres
Properties that need ultimately to be measured to characterise greasy mohair completely include the following: 1 2 3 4 5 6 7 8 9
Fibre diameter and its distribution. Yield. Staple (or fibre) length and strength, and its variability. Vegetable matter content and type. Inorganic matter content. Colour. Lustre. Medullation/kemp. Style/character.
Douglas193 discussed the advantages of objective measurement of mohair. He stated that the mohair top must achieve strict specifications to satisfy the spinning requirements that include requirements for: – – – – – – – – – – –
Quantity of top. Mean fibre diameter. Mean fibre length. Distribution (CV %) of fibre length. short fibres (shorter than 30 mm). dark fibre content. Maximum percentage of vegetable matter speck contamination. entanglement (Neps). fatty matter content. Moisture regain. Maximum percentage of kemp content (specifically for mohair).
{
In addition, some spinners may have specifications which include:193 – – –
Colour. Distribution (CV %) of fibre diameter. Bundle strength.
If specifications are incorrect, quality and productivity fail.193 Douglas193 emphasised that the variability of natural products, such as mohair, necessitated proper (representative) sampling and adequate testing in order to obtain an accurate and reliable result. Mohair base (i.e. the amount of clean dry fibre, free from all impurities, expressed as a percentage of the greasy fibre mass) is converted into the International Wool Textile Organisation (IWTO) scoured yield basis.193 This relates the tested yield to normal commercial yields for scoured greasy mohair. This yield is calculated from the mohair base to include all vegetable matter, standard residuals of grease and dirt, which would normally
Mohair
95
be retained in commercial scouring, and allows for moisture regain of 17 % which means that yields of over 100 % are possible. Qi et al.194 applied image analysis to the objective measurement of mohair and other animal fibre properties, such as diameter and its variation, staple length, colour and coloured fibres. Various workers121,195 have also reported on the application of Near Infrared Spectroscopy (NIRS) for measuring mohair characteristics, such as diameter, medullation and yield (Mohair Base), while other workers have successfully applied image analysis (e.g. OFDA) to the measurement of diameter, medullation and curvature.
2.3.7 Fineness There can be little doubt that mohair fineness (diameter) is one of its most important characteristics from the point of view of price and textile application and performance, with a 1 mm change in diameter having a significant effect on price (Fig. 2.14). It is therefore not surprising that fibre diameter, that can be measured by airflow, projection microscope, FDA, OFDA or Laserscan, is generally the first objectively measured mohair characteristic. Mean fibre diameter is the parameter most generally measured and reported, although the distribution of fibre diameter, in terms of CV, also has textile significance. A major step forward in improving and standardising the interlaboratory measurement of mohair fibre fineness occurred upon the introduction of the Mohairlabs International Round Trials and associated issuing of Mohairlabs stamps (see ‘Mohairlabs’, Section 2.6.4).
2000 1800 1600 US cents/kg
1400 1200 1000 800 600 400 200 0
<=27 28 29 30 31 32 33 34 35 36 37 38 39 >=40 µm
2.14 Average 1999 prices per micron (fineness) for South African mohair.
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Silk, mohair, cashmere and other luxury fibres 1000
US cents/kg
800 600 400 200 0 125–150
100–125
75–100
<75
Length (mm)
2.15 Average 1999 prices of the various length classes of South African mohair. 1800 1600
US cents/kg
1400 1200 1000 800 600 400 200 0 Super
Good
Average Plus
Average
Poor
Style and Character
2.16 Average 1999 prices of various style and character classes of South African mohair.
The variation of price (in US cents/kg) against different characteristics is shown in Figs 2.14, 2.15, 2.16 and 2.17. Hunter et al.196 studied the diameter and variation in diameter, as measured by projection microscope, of some 852 samples of raw and scoured mohair and 380 mohair tops. They found that, although standard deviation tends to increase with increasing mean fibre diameter, the relationship was a tenuous one and the scatter large. There was a tendency for CV to decrease as mean fibre diameter increased up to a mean fibre diameter of somewhere around 35 mm, after which the reverse occurred. For most
Mohair
97
2000
US cents/kg
1600 1200 800 600 400 0
Fine Kid
Strong Kid
Fine Strong Young Young Goat Goat Age
Fine Adult
Strong Adult
2.17 Average 1999 prices of South African mohair of different age groups.
Table 2.15 Average values of coefficient of variation of fibre diameter corresponding to different mean fibre diameters196 Mean fibre diameter (mm)
CV of fibre diameter (%)
25 30 35 40 45
30 27 26 27 29
practical purposes, however, the CV of diameter could be regarded as independent of mean fibre diameter, with an average value of approximately 27 %. Some 95 % of the CV values were found to lie between approximately 23 and 32 %. The average standard deviation of fibre diameter for the samples was 8.7 mm, with more than 95 % of the values lying between 6 and 12 mm. The data are shown in Table 2.15, which gives average (typical) values for CV of fibre diameter. Wang et al.197 showed that there was a relationship between coefficient of variation (CV) of mohair fibre diameter and CV of single fibre strength as predicted theoretically. Turpie and co-workers198,199,200,201 as well as others202 reported on the calibration and application of the FDA200 for the rapid measurement of mohair fibre diameter and its distribution. It was concluded that, within the ranges covered, kemp level had little effect on the
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Table 2.16 Fineness measurements of US commercial mohair tops38 Grades
Kid Super Kid 40s 36s 32s First 28s 26s 24s Low-second
Average (mm)
Deviation (mm)
CV (%)
Standard error (mm)
Average range (mm)
Dispersion range (mm)
25.7 27.0 28.7 30.0
6.30 5.29 6.23 6.89
24.5 19.1 21.7 22.9
0.19 0.17 0.19 0.22
25.2–26.3 26.5–27.5 28.1–29.2 29.4–30.7
10–45 10–45 10–50 10–50
32.2 34.0 35.7 41.1
7.81 7.99 9.25 10.60
20.5 23.5 25.7 25.6
0.24 0.25 0.29 0.30
31.5–32.9 33.3–34.8 34.8–36.5 40.5–42.3
10–55 15–55 15–60 20–70
relationship between FDA, projection microscope and airflow diameter values. Turpie et al.161 found that different calibrations are required for mohair and wool on both the FDA200 and the OFDA. Various ASTM and USDA test methods and standards for the fineness of mohair (greasy and top) and the assignment of Grade have been published over the years.203,204,205,206,207,208,209 The fineness measurement of some US commercial mohair tops is given in Table 2.16.38
2.3.8 Staple length and strength Turpie and co-workers157,210,211,212,213,214 reported results for the staple length, strength and profile of mohair as measured automatically by means of the SAWTRI Automatic Staple Length/Strength Tester. Using the staple crosssectional profile (taper diagrams) and a technique of best-fit trapeziums, they showed that the staple profile and length distribution could be used to predict the fibre length distribution of the staple and the top. The mohair staple has a very pronounced taper, indicating a fairly wide variation in fibre length within the staple. There was a reasonably good correlation between mohair staple length measured manually and that measured by the automatic staple length/strength tester. An attempt was also made to relate staple profile to style and character, with some success.
2.3.9 Quality and related characteristics The quality of mohair is described as a combination of style and character, freedom from kemp, lustre, handle, yolk and uniformity of length and fine-
Mohair
99
ness.215 The presence of kemp is often the most undesirable quality characteristic of mohair. Handle is largely determined by fineness, although a soft natural yolk and oleaginous dips also improve softness of handle. Mohair characteristics of economic importance (see Figs 2.14, 2.15, 2.16 and 2.17) are fineness (fibre diameter), length, style and character, contamination (kemp, coloured fibres and vegetable matter), and clean yield and uniformity in general, fibre diameter being the most important followed by kemp with length having a smaller, though still important, effect on price and processing as do style and character. According to Van Der Westhuysen216 mohair price (averaged over a ten year period) decreased by about 5 % for each 1 mm increase in fibre diameter, stabilising at about 34 mm with a price of about 55 % of the maximum value (paid for 26 mm mohair). Price was less affected by length, the maximum price being paid for about a 15 cm staple length, representing approximately 6 months’ growth. Since there appears to be no benefit in production efficiency from shearing more than twice a year, there is no economic justification for shearing hair that is under 75 mm.3 Major burr and grass seed contaminants of mohair result in serious price penalties and so do kemp levels, vegetable fault mohair fetching about half the average price of other mohair types.217 Any undesirable contaminant, that will either affect the quality of the final product or will have to be removed, reduces the economic value of the mohair. Coloured (e.g. black or red) fibres, if present, could affect the finished cloth, particularly if light shades are dyed, and thereby the value of the mohair. Burrs or excessive vegetable matter in the fleece also have to be removed.3 Urine and certain types of soil and vegetable matter contain substances which stain mohair permanently.3 These affect the dyeing and value of the mohair and the quality of the final product. Precautions must be taken to limit such stains, particularly urine stains.3 Clean yield (i.e. the percentage of actual fibre plus commercially allowed moisture content in raw mohair) generally varies between about 80 and 90 % in most fleece classes, but may be as low as 60 % in some outsorts, such as lox (locks), the remaining portion being made up of grease, dirt, dust and sweat. Style and character are judged subjectively, high quality style being described as solid-twisted ringlets (staples or locks), while character is described as the waviness or crimp shown in the staple.3,143 Style without character or vice versa is undesirable, and a good balance between these two characteristics is considered to be of paramount importance.3,143 The simplest description of good classing has been given as uniformity within each class of length, fineness, style and character and degree of contamination (kemp, vegetable matter and stain).143 An important objective of classing is therefore to achieve uniformity of quality, particularly fine-
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Silk, mohair, cashmere and other luxury fibres
Table 2.17 Some approximate quality types2 Spinning count
English grades
Fineness /quality Bradford count
Age group
Crimp* per 10 cm
Maximum mean diameter (mm)
Mean fibre diameter (mm)
Description
Age (years)
Kids Kids Kids — Young Goat Adult Adult Adult —
6.5–8.0 5.5–6.5 5.5 — 5.0–5.5
25 28 30 32 34
<26 26–28 29–30 — 31–34
SSK SWK WSK — SYG
1 /2 1 — — 11/2
4.0–5.0 3.0–4.0 2.5–3.0 1.5–2.5
36 39 — —
35–36 37–39 >40 —
SWH SSF SFO WHO ARH CBH
2 21/2 2 2 — —
Tex
Worsted
14.5–15.5 16 16.7–17.5 — 18.5–19.5
58–60s 56s 50–54s — 46–48s
— Kid 30 — 32
8 7 6 6/5 5
20 22–24.5 24.5–27.5 31.5
44s 36–40s 32–36s 28s
34 36 38 40
4 3 2 1
* Preliminary. SSK – Super Summer Kids WSK – Winter/Summer Kids SWH – Super Winter Hair SFO – Summer First and Older ARH – Adult (Ram’s Hair) SWK – Super Winter Kids SYG – Summer Young Goats SSF – Super Summer Ferals WHO – Winter Hair and Older CBH – Cross-bred Hair (Adult)
ness (diameter), and classing standards and regulations are laid down and continuously updated in most of the important mohair-producing countries. Classing, therefore, must separate the different parts of the fleece which differ noticeably in one or more important characteristics.
2.3.10 Grades Much of the information in this section is merely of historical interest, since the trend is to categorise (grade) mohair on the basis of objectively measured characteristics, notably diameter (fineness). The grades of mohair vary in different countries. In general the best grades of mohair are from kids under six months old (i.e. first shearing). Table 2.17 is an attempt to consolidate and rationalise some of the different systems of quality, fineness and grades encountered in the literature.
Mohair
101
Table 2.18 Spinning limits and quality of mohair compared219 Spinning limit
Mohair quality
Worsted
Tex
16’s 24’s 28’s 32’s 40’s 44’s 50’s
55 37 32 27 22 20 18
1’s 2’s 3’s 4’s 5’s 6’s 7’s
2.3.11 Spinning limits and quality Mohair is often considered to be very difficult to spin because of its smoothness and lack of cohesion. Nevertheless, provided the correct processing additives and conditions and raw materials are used, very high quality mohair yarn can be spun with acceptable efficiencies. The finest yarn which can be spun largely depends upon the mohair fibre diameter or fineness, traditionally expressed in terms of ‘quality or quality counts’, and these are related to the minimum number of fibres in the yarn cross-section. Today, mohair fineness is almost solely expressed in terms of the objectively measured mean fibre diameter. According to Wood,218 the finest mohair yarns were originally spun on the flyer method, using the Bradford worsted system. Villers219 described the traditional processing of mohair, and detailed comparisons of the spinning limits of mohair with its quality as given in Table 2.18. He stated that mohair was rarely spun finer than a 40’s worsted count (i.e. 22 tex).
2.3.12 Scouring Scouring is a critical process in mohair production and often it is at this stage that the ultimate state of the finished article is decided. As previously mentioned, mohair generally contains far fewer impurities than does wool220,221 (e.g. 4 to 6 % of grease compared to about 15 % for merino wool)222 and scouring generally causes a loss in mass of between 15 and 20 %.10 Mohair is generally regarded as more sensitive to alkali than wool. Therefore less, or even no, soda-ash should be used during scouring220,221 and non-ionic detergents are preferred today.
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Silk, mohair, cashmere and other luxury fibres
Before scouring, individual mohair bales are often sorted on screens for style and quality, frequently up to eight different kinds being obtained from a single bale,223 efficient sorting and blending playing an important role in the eventual quality of the yarn. The fibre can then be willeyed (opening/cleaning) before it is scoured, and this is advisable. Scouring conditions for mohair are generally gentler than they are for wool and it has been suggested that the first bowl temperature is strictly controlled to no higher than 50 °C, dropping to about 40 ° or 45 °C in the last bowl.11,223 Alkali need not be used and the scouring rate is generally much lower than the capacity of the scouring train.223 The pH must also be strictly controlled and in a 3-bowl scouring set the pH of the first bowl could be 10.5, that of the second bowl 9.5 and that of the third bowl 8.5, and 4 or 5 bowls are preferable. Excess alkali in the fibre can lead to discolouration in dyeing.11 Where a non-ionic detergent is used without any alkali, it is possible to have first bowl temperatures as high as 60 °C, whereas if an alkali is used, the first bowl temperature should not exceed 55 °C. Care must also be taken during scouring not to impair the lustre of mohair, hence soda-ash is often only used in the first bowl224 or even omitted altogether. Spencer11 suggested that mohair should be scoured to a residual grease level of 0.6 % and that l to l.2 % of combing oil should be added to give a total fatty matter content of 1.6 to 1.8 %, which was considered ideal, for the Bradford system. A series of pilot-scale experiments on the scouring of mohair was carried out at SAWTRI in the 1960s.220,221,224 Kriel,189,220 quoting unpublished work by Veldsman, stated that a higher consumption of detergent was required to remove 1 g of grease from mohair than from wool, the generally lower level of grease (4 to 6 %) in mohair as well as its more oxidised nature, because of greater weathering than in the case of wool, being relevant factors. A second bowl temperature of 50 °C was judged better than one of 45 °C, the third bowl temperature being kept constant at 45 °C and that of the fourth bowl at 40 °C. Increasing the first bowl temperature from 45 to 55 °C increased the grease removal, the residual grease decreasing linearly from 0.9 to 0.2 %.189,221 Grové and Albertyn224 concluded that it was unwise to exceed 55 °C in either the first or second bowls when scouring mohair, particularly when using soda-ash. Soda-ash, if used in the first bowl, should also be restricted to 2 % (mass on mass of raw mohair).224 It has also been stated that the scouring liquor should preferably not exceed 45 °C and the drying temperature not be above 55 °C10, and that a pH of 9 is considered suitable for mohair scouring. For the Continental worsted system (French or rectilinear comb) of processing, which is very popular today, scouring to a residual grease content of 0.2 to 0.3 % is advisable, with a total fatty matter level of between 0.7 and 0.9 % (up to 1.2 % for flexible card clothing) prior to carding. After scouring (which normally takes place at between 45 and 55 °C),143 the fibre can
Mohair
103
be dried to a moisture regain of about 20 % for the longer lengths and about 25 % for the shorter types, the higher regain helping to control fly during carding.223 Drying temperatures should be as low as possible, e.g. 80 °C. Turpie and Musmeci,222 investigating the centrifugal treatment of mohair scouring liquors, found that the grease recovery potential from such liquors was rather poor, with the choice of non-ionic detergents having a noticeable effect on the results obtained. Mozes and Turpie225 reported on the treatment of mohair scouring liquors (using hollow fibre pilot-scale ultrafiltration membrane separation) as well as on the particle size distribution of suspended solid dirt in a range of industrial raw wool, mohair and karakul aqueous scouring wastes.226 Mozes227 reviewed literature published on the treatment and purification of wool and mohair scouring wastes, much of the information on wool also being applicable to mohair. Turpie et al.228,229,230 reported on the membrane treatment of wool and mohair scouring effluents from an industrial operation.
2.3.13 Carbonising Very little mohair (±2 %) is normally classified as carbonising, although in high rainfall areas and seasons it can rise to as high as 15 %; mohair with vegetable matter exceeding 3 % is normally carbonised. According to Pfeiffer et al.231 vegetable matter (defect), such as burrs, seeds, twigs and other plant parts that become entrapped in the goat fleeces can pose serious problems in the manufacture of textiles. Some vegetable matter is inevitable but excess amounts increase waste in the carding and combing processes. Some types of vegetable matter cannot be physically removed by carding and combing and may require carbonising, a method using acid, normally sulphuric, followed by baking, crushing and de-dusting to remove cellulosic contaminants completely. This process, which follows scouring, is expensive and results in decreased fibre lustre and strength. Hence, mohair buyers are prepared to pay more for mohair free of vegetable matter contamination. It has been stated232 that the sulphuric acid content of mohair prior to baking should be less than 6 % and that carbonising is normally resorted to when the vegetable matter exceeds 3 %.143 Most carbonised mohair is sold for processing on the woollen system. Nevertheless, Turpie233,234 showed that a mild carbonising treatment (±2.5 % acid as opposed to 6 or 7 % and baking at 115 °C for 60 s) can be advantageous for further processing on the worsted system. Generally, only about 2 % of the Cape mohair clip is classified as carbonising.235 Seasons of high rainfall, however, can result in abundant growth of grass and other vegetation and the presence of undesirable seeds in excessive quantity and therefore of considerably higher (up to 12 %) of mohair classified as carbonising types.
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2.4
Yarn and fabric manufacture
2.4.1 General In converting mohair into yarn, similar machinery is used as in the case of wool. Nevertheless, mohair is not an easy fibre to process, particularly in drawing and spinning. Considerable secrecy exists even today concerning the precise processing conditions used; firms which have built up this specialised knowledge do not share it because it provides them with a competitive edge. It is generally easier to disentangle mohair than wool during carding, with less fibre breakage in this process, although problems with fly generation often necessitate lower carding speeds. Mohair’s low cohesion often necessitates that the fibres (slivers) be supported, for example by aprons, during processing. The efficient mechanical processing of mohair into quality yarn is widely accepted to be a highly specialised field, requiring considerable skill, experience and practical knowledge. Mohair can present problems during processing due to its lack of cohesion (smoothness) and the generation of static electricity. Mohair blends well with wool, however, and wool facilitates its processing. The application of the correct types and levels of processing lubricants and additives (such as antistatics) and the selection of the most appropriate processing machinery and conditions (including atmospheric) are all crucial in the efficient processing of mohair into a quality product. Today, the bulk of mohair is processed on the Continental or dry-combed (French/rectilinear combing) as opposed to the oil-combed system. Nevertheless, most of the shorter mohair and also a significant amount of longer hair as well as mohair waste, such as carbonised noils, are processed on the woollen system. For the woollen system, a minimum amount of vegetable matter is essential (see the section on carbonising (2.3.13)). The final web is normally taken off the card by a Tape Condenser, with special attention to splitting the web and rubbing it, as well as to the choice of rubbing leathers. For woollen carding, an oil and antistatic are applied to the level of about 5 %, a 1-part Scribbler with Breast, a 1-part Intermediate and a 1-part Carder generally being adequate, flexible clothing being used. The handling of the web normally requires special attention, Broad Band feeds being ideal, a Scotch feed being possible for blends with wool. Traditionally, mohair was processed on the Bradford worsted (oilcombed) system (drafting against twist) followed by flyer spinning.236 In earlier times, some mohair qualities used to be double Noble-combed, some Noble- and then Lister-combed and some single-combed, the Noble comb being advantageous for kemp removal. Today, mohair is mainly processed on the French (continental or dry-combed) system of drafting and spinning237 involving French (rectilinear) combing. It is possible to use either
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flyer (twisted) roving or rubbed (twistless) roving for subsequent yarn spinning. In woollen spinning, mohair shorter than 75 mm is generally used while on the Bradford (worsted) system the length is generally 90 mm and longer, with a staple length of some 120 mm often required for worsted processing.166 In order to qualify for a spinners type, which is the top end of the market, a minimum staple length of 125 mm is reportedly required.238
2.4.2 Worsted processing Mohair is most commonly carded on single swift cards, the forepart equipped with burr beaters and morel roller to deal with vegetable contaminants. Lower swift speeds than those used for wool are applied so as to minimise fly and other problems. Card losses usually lie between 3 and 7 % but could exceed 10 % for types of mohair that have an exceptional number of seeds. It is important to apply a suitable lubricant (having good cohesion and antistatic properties) to the mohair prior to carding. Three gilling operations generally follow carding, with lubricant/antistatic being added, by spraying, prior to combing to increase the dichloromethane (DCM) extractable matter level to 1 to 1.2 % for dry-combing and 3 to 3.5 % for Noble oil-combing. It is normal practice to gill combed mohair twice, using autoleveller intersecting gill boxes, to produce commercial tops, because it is important to use cans with springs to support the hair, and ensure delivery in the form of a bump rather than a ball. Spinning can take place on mohair oil-combed tops using the flyer system or Bradford system of drawing and spinning, employing the draft-againsttwist principle, the twist in the roving providing cohesion and controlling the drafting action. More commonly today, the continental system of drawing and spinning is applied, using dry-combed tops, drawing involving two stages of intersecting gill boxes followed by a passage through a doubleapron high-draft draw box. In preparation for spinning, either twisted roving can be produced on a Flyer (Speed frame) or rubbed (false twist) roving on a rubbing frame or false twist rover. It is believed239,240,241 that mohair top and roving should be rested or stored for prolonged periods of weeks between the various stages of its mechanical processing from top to yarn. It used to be customary to rest mohair tops for extended periods (e.g. six weeks) after combing (or topmaking)239,240,241 and also after the drawing operation in roving form243 so as to improve spinning and reduce waste. The subsequent improvements in spinning performance and reduction in fly waste were ascribed to the dissipation of static electricity.239
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Parkin and Blackburn241,244 found that, in the case of Cap spinning, storage reduced static electricity on the rovings and end breakage as well as waste during spinning. The rovings were found to reach equilibrium regain after approximately one week of storage. Yarn evenness, strength and elongation generally improved with increasing periods of roving storage, with yarn twist liveliness increasing with roving storage until it reached a maximum after about 18 weeks storage. Yarn hairiness first increased and then decreased with longer roving storage time. Parkin and Blackburn concluded,245 however, that although roving storage resulted in improved yarn properties, particularly in the finer count, the improvements were generally too small for storage to be of commercial benefit. They also concluded that measuring the cohesive properties of mohair rovings should provide a measure of spinning performance and yarn properties.
2.4.3 Yarn hairiness It has been found that mohair yarn hairiness was reduced by roving storage, decreasing fibre diameter, plying and increasing fibre length (Barella and co-workers and Turpie and Hunter quoted by Hunter2).
2.4.4 Fancy (novelty) yarns Mohair is used to particular advantage in fancy or novelty yarns, such as loop, knop, brushed, bouclé, flame, snarl, slub and gimp, where its properties provide outstanding aesthetic appeal and comfort. Such yarns are used in blankets, stoles, shawls, scarves, knitwear (sweaters, cardigans, jerseys), travel rugs, curtaining, table coverings, upholstery, furnishings, pram covers, women’s dresswear, suitings and coatings. Traditionally, mohair yarns, particularly loop yarns, were raised after knitting by passing the fabric through a teazle machine. Although loop yarns are often brushed prior to fabric manufacture, they can also be converted into fabric and then brushed to give the desired light and fleecy appearance. Adult hair is often used to form the loops of bouclé yarn properly.259 Curl yarn is produced by twisting a number of yarns together, setting the yarn (e.g. boiling at pH 6.7) and then untwisting and separating the individual yarns again. Metchette260 has discussed the spinning and dyeing of fancy yarns.
2.4.5 Fabric production and machinery Generally, mohair yarn is converted into knitted and woven fabrics using similar equipment as for wool, though sometimes in a modified or adapted form and under special conditions.
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2.4.6 Weaving and woven fabric properties Mohair finds significant application in woven suiting and coating type fabrics, particularly in men’s light-weight summer (tropical) suitings where it provides the wearer with considerable comfort and good wrinkle resistance.
2.4.7 Wrinkle recovery Mohair is widely recognised as having very good wrinkle resistance and recovery, which, together with its stiffness, make it an ideal fibre for use in comfortable light-weight tropical type fabrics. Nevertheless, laboratory tests for wrinkling are often at variance with perceived and actual performance in wear, with different laboratory tests also often providing contradictory results. For example, according to the Thermobench wrinkle recovery test mohair was superior to wool, whereas according to the AKU test there was little difference between the two fibres, at the same mean fibre diameter. Ageing has a considerable effect on laboratory test results. According to laboratory tests, wrinkle recovery actually deteriorates with an increase in fibre diameter, which is contrary to widely held beliefs.280 The reader is referred to Hunter2 for more detailed information on this subject. The fibre and fabric properties of mohair and their relationship to other variables are discussed in Appendix 5.
2.4.8 Knitting and knitted fabric properties Mohair, often in blends with other natural fibres, notably wool, is used to great advantage in knitwear, mostly in brushed, loop or some other fancy form, particularly to impart a soft, lustrous and brushed appearance. Knitwear traditionally represented some 80 % of mohair’s outlets, but this sector is fairly sensitive to cyclical fashion changes. Historically, large quantities have been used in women’s sweaters, the brushed appearance being typical, producing a highly lustrous fabric. The medium grades of mohair (24s, 28s, 32s and 36s) are mainly used in knitted outerwear. For machine knitting, 36 to 37 mm mohair has proved fairly popular,281 with 37 to 39 mm being used for hand knitting. Kid and Young Goat mohair is used in machine knitting and Young Goat and even Adult hair in hand knitting. With the trend towards softness and lightness, more and more Kid mohair (and Young Goat mohair) has found its way into the knitting trade, even for the brushed look.281
2.4.9 Dyeing and finishing 2.4.9.1 General It is generally the case that firms which dye and finish mohair also dye and finish wool and hence similar machinery is used for the two fibres, although
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often under different conditions. Furthermore, it is nowadays very rare to find pure mohair in yarns and fabrics; it is mostly present in blends with wool, which means that the dyeing and finishing machinery and conditions used must be suited to both fibres. In general, weak acid-dyeing dyestuffs are used for light/bright shades and acid milling, super milling and reactive dyestuffs for medium and dark shades. It is common practice to dye at temperatures below the boil, preferably below 90 °C and to limit the time of dyeing at high temperatures, so as to curtail any adverse effects on lustre and other desirable properties. It is also possible to limit damage to the fibre by using fibre protective agents. The pH of the dyebath should ideally lie between 4.5 and 5.5 and should never exceed 6.5. Dyeing and finishing represent crucial stages in the manufacture of mohair products of the outstanding quality and appearance associated with items bearing the label ‘mohair’. Although the dyeing and finishing of mohair, including the machinery used, are similar to those used for wool, certain differences and special precautions are often necessary for mohair, particularly so as to preserve its lustre, brilliant colours and other desirable properties. Although a vast literature exists on the dyeing and finishing of wool, much of which is applicable to mohair, there is far less literature available on the specialised knowledge of conditions and procedures required for the dyeing and finishing of mohair products because most of such knowledge is a well-kept secret. In general, milder conditions are used for the dyeing and finishing of mohair than for wool, partly because of the need to conserve the lustre of mohair and partly because mohair is more sensitive to wet treatments than is wool. Veldsman stated284 that the finishing procedure of light-weight wool/mohair fabrics is a highly secretive affair, and it appears that reputed firms have constructed special machines or techniques to achieve a highly lustrous, resilient cloth. The following sequence of finishing operations was found to give a commercially acceptable fabric.284 – – – – – – –
Crabbing at the boil. Piece scouring (open width, if at all possible). Steaming and brushing. Shearing (the last two operations can be repeated, if deemed necessary). Blowing (decatising). Hydraulic pressing. Autoclave setting (KD process).
Further details concerning dyeing and finishing are set out in Appendix 6.
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2.4.9.2 Flammability Keratin fibres, such as mohair, have traditionally been regarded as being safe from the point of view of flammability. Mohair may be ignited if subjected to a sufficiently powerful heat source, but will normally not support combustion and will smoulder for only a short period after the heat source has been removed. This can be ascribed to the high ignition temperature, low heat of combustion and low flame temperature of the fibre. The natural flame resistance of mohair is connected with its chemical and morphological structure. Mohair was one of the few fibres which met most of the earlier requirements for flame retardancy for contract markets (e.g. office furniture, hotels and theatres). Nevertheless, although, like wool, mohair does not burn easily, it cannot be regarded as completely flame resistant, and flame proofing is necessary for it to conform to modern specifications for flame resistance. Traditional high-density mohair and wool carpets were acceptable without treatment but fashionable long-pile low-density structures were classed as hazardous unless specially treated. The Limiting Oxygen Index (LOI) of mohair is about 24, with 27 generally regarded as the minimum required to pass the vertical flame test. By blending mohair with certain synthetic fibres or with cotton, the problem of flammability could become more serious because these latter fibres often burn easily in the untreated state. 2.4.9.3 ‘Easy care’ finishes An area which is now receiving attention is the development of easy-care wool and mohair knitwear garments, which can be washed in a washing machine without any adverse effect on the garment dimensions or appearance.290
2.5
Mohair production in various countries
2.5.1 South Africa The first Angora goats to leave Turkey reached South Africa in 1838 and were imported by Henderson. South Africa presently accounts for over 60 % of the world mohair production; its mohair is generally known as Cape mohair and is widely regarded as one of the most superior, finest, best prepared and highest yielding in the world. The excellent quality of Cape mohair makes it ideally suited to high quality application, e.g. high quality men’s wear and women’s wear, fineness and length being important in both cases. Van Der Westhuysen et al.143 published a book on the Angora goats and mohair in South Africa, covering the production of mohair and its clas-
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sification. Uys156 described the history of mohair in South Africa from 1838 to 1988, mentioning that the first mohair tops were produced in 1963 at Gubb & Inggs. Today, some 95 % of South African mohair is exported, the distribution being carried out in a free market system. The South African Mohair Growers’ Association was re-established on 16 August 1941, having previously existed from 1896 to 1904. The South African Mohair Growers’ Association is funded by Mohair South Africa from income generated by the Mohair Trust, the assets of which were built up over many years by the mohair growers of South Africa, and for whom there are neither subsidies nor incentive schemes. Mohair South Africa was formed in 1998 to take over some of the responsibilities and duties of the Mohair Board that was formed in 1965 and disbanded in 1997. Mohair South Africa is a beneficiary of the Mohair Trust. The Angora Goat Stud Breeders’ Society has been in existence for over 100 years. There are presently (year 2000) approximately 2000 mohair farmers in South Africa, farming with just under 1.2 million goats and producing about 4.5 mkg of mohair; average annual greasy mohair production per goat is 4 kg at an average clean yield of about 85 %. Mohair is mainly produced in the Cape Province, more specifically the Eastern Cape area, within 300 km distance from Port Elizabeth. In 2000 the annual value of the South African mohair clip was about 225 million rand (32.5 million US dollars) with the value of the fabric being about 2500 million rand.
2.5.2 United States of America Angora goats were first introduced into the USA in 1849, from Asiatic Turkey. In the United States of America, as in South Africa, there are two mohair clips each year, the one termed Spring (shearing in February/ March) and the other Fall (shearing in August/September),158 most of the mohair being produced in the south-western United States. In the USA, Angoras are largely concentrated in Texas, with smaller numbers in New Mexico, Oklahoma, Michigan and other states.15 Texas produces about 96 % of the total US mohair production, with the most important area being the Edwards Plateau in south-western Texas which accounts for about 90 % of production. Here the mild dry climate and hilly, bushy terrain are particularly suited to the well-being of the goats. Mohair in Texas is mainly grown in the area circumscribed by Uvalde, San Antonio, Austin, Fort Worth and San Angelo. In Texas, mohair is sold through various warehouses in a free market system in which producers have the final say over the sale of their product. The Mohair Council of America was established in 1966 as the promotional organisation for mohair produced in the United States and is involved in marketing, development and research; the executive offices are located in San Angelo. It is primarily funded through a check-
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off programme in Texas, involving a 0.04$/lb (0.088$/kg) levy (assessment) on all mohair sold in Texas, collected through the Mohair Producers’ Board. There are no federal government incentives or check-off programmes for mohair producers. The USA market has established various grades of product, based on staple or lock characteristics, from the ringlets of the finest fleece to flat locks in which the curl is less pronounced and takes on the form of a wave.160 Classing is mainly associated with grading for fineness, and length is also a criterion;160 there are only 9 basic grades for mohair.161 The hair is generally not skirted but is normally separated into Kid, Young Goat and Adult. About 98 % of the US mohair production is exported.159 Performance testing of Angora goats is undertaken at the Texas A & M Centre.162 Lupton et al.163 discussed the performance testing of Angora goats in Texas and reported that during the 8-year period under consideration, average clean mohair production of yearling buck increased from 4.6 to 5.5 kg (180-day basis), while clean yield, fibre diameter and staple length remained constant, at about 69 %, 40 mm and 150 mm respectively. Kemp (0.4 %) also remained approximately constant, but medullation increased from about 1.3 to 3.3 % (average about 2 %). Kemp content was not correlated with any of the measured characteristics except medullation, where the correlation was 0.33. The average annual mohair yield per goat is about 4 kg. At the beginning of 1999 there were some 631 000 Angora goats in the USA.
2.5.3 Turkey There can be little doubt that the world mohair industry, as we know it today, had its origins in Turkey. In Turkey there is normally only a spring clip each year,164 the goats being shorn once a year during May.165 An official grading standard exists, with the hair normally sorted, by exporters, into First Kid, Best Average (Young Goat), Good Average (Fine Adult), Fair Average (Low Adult) and Mountain Konia (mountain hair about 31/32 mm). The clean scoured yield is about 70 to 75 %. Mohair-growing in Turkey is concentrated in the central provinces of the Anatolian peninsula (within a radius of approximately 160 km from Ankara) where the summers are hot and dry and the winters cold with frequent snowfalls. The mohair clip is sold in its unclassed state, although exporters grade before exporting hair. Mohair for export is divided into two categories, namely Principal Mohair and Secondary Mohair, with the former divided into nine classes and the latter into eight. The grease content is usually less than 4 %. The best grades are clear white. In Turkey, a reddish brown mohair, containing a colour pigment, and known as Gingerline, is produced.
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2.5.4 Australia Angora goats were first imported into Australia as early as 1856,15 but the Australian mohair industry only really started to expand in about 1970.166 In Australia, the Angora goats are mostly shorn twice a year165 (in the past, they were sometimes shorn at 9 months) and graded into standard qualities (various grades of Kids, Young Goats and Adults), depending upon quality and kemp content. Classers grade mohair into Super, Good and Average Style and Character categories. Cotting is classed into soft and hard cott.155 Pigmentation is severely penalised. Stains must be skirted from the fleece which increases with increasing coverage and fleece weight.155 The scoured yields are approximately 88 to 90 % and the colour good.165 Australian mohair is considered to be relatively fine and kempy,167,168,169 kemp being present in varying degrees, from FNF (free/nearly free) to very kempy cross-bred.165 There is now a single classing standard for Australian mohair.169 Harmsworth170 gave some details of Australian mohair as seen through the eyes of some Bradford merchants, while aspects of mohair production in Australia have been discussed by Stapleton155 and others.171,172,173 According to Stapleton174,175 and Gifford et al.176 as quoted by Stapleton,155 Australian mohair has a yield of about 90 %, a mean fibre diameter ranging from 24 mm at the first shearing, 26 mm at the second, 30 mm at the third and fourth shearing and about 33 mm at later shearings, and the kemp levels at about 2 %. Fleece mass increases rapidly to the third shearing, reaches a peak at the fifth or sixth shearing and then gradually declines showing some seasonal effect.155 In Australia, the maximum greasy fleece weights range from about 1.4 to 1.9 kg, at 6 months. Recent infusions of new bloodlines from South Africa and Texas are stated to be one of the most potentially beneficial events in the history of Australian Angoras.177 The MOPLAN performance recording system in Australia has been referred to in an anonymous paper.178
2.5.5 New Zealand In about 1860, Angora goats were brought to New Zealand from Australia,182 and approximately 20 000 Angora goats were imported into New Zealand from Australia during the early 1980s. Woodward179 discussed the increasing production of mohair in New Zealand, explaining the breeding strategies of goat farmers. In 1992 the New Zealand clip was marketed through two separate companies.180 At the turn of this century (2000), New Zealand produced about 3 % of the world mohair.181 Shearing takes place every six to nine months. Mohair production in New Zealand and Australia has been discussed in various articles,167,182,183,184 the mohair tending to be
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relatively fine, high yielding182 and kempy. The scoured yield is mostly around 88 to 90 %, and the colour good. Kemp is present to varying degrees, from nearly free to very kempy cross-bred.165 Bigham et al.185 stated that the levels of kemp and medullation in New Zealand mohair were high relative to those in Texas and Cape mohair, but steps to rectify this, such as the use of imported low-kemp breeding stock and a dekemping process, were in progress.5
2.5.6 United Kingdom Ryder186,187,188 reported on the very small production of mohair in the United Kingdom and on the development of the Angora goat industry there.
2.5.7 Argentina In Argentina there are generally two clips each year, namely in March (short) and November (long).165 Sorting is mostly done by the exporters, the scoured yields are approximately 75 to 80 % with the colour good but the hair relatively kempy.165 In 1985 guidelines for the classing and types of mohair were approved by the Department of Agriculture for application in the entire country.
2.6
Marketing and cost considerations
The textile application of mohair goes back many thousands of years, the fibre finding application in almost every conceivable textile end-use. Today, up to 80 to 90 % of mohair consumption, especially of the Adult hair, can be affected by fashion.
2.6.1 The end-uses of mohair Table 2.19 lists some of the end-uses of mohair, and a detailed list of mohair applications is given in Appendix 7 (after Hunter2). The presence of mohair in a material is considered to lend elegance and quality to it, mohair being sought after for its comfort, resilience and durability. For example, in lean worsted-type light-weight tropical suitings, mohair is regarded as a cool fibre, whereas in brushed articles, such as shawls, stoles, rugs, sweaters and blankets, mohair provides warmth without weight. Velours, also embossed, have always been one of the most popular outlets for mohair. Mohair’s characteristics of hard-wearing durability, resilience or springiness, moisture absorption, comfort, lustre and smoothness make it ideally suited to many applications in apparel and interior textiles. Because of its general smooth-
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Silk, mohair, cashmere and other luxury fibres Table 2.19 Mohair consumption by end-uses291 End-uses
Share (%)
Hand-knitting yarns Men’s suiting fabrics Women’s woven accessories and rugs Woven furnishings and velours
65 15 12 8
ness and low static propensity, except under dry conditions, mohair does not collect dust or soil very easily and is also easily cleaned. Traditional mainstays of mohair have been blankets, stoles, scarves, travel rugs and hand-knitting yarns, fluffy look women’s wear in fancy yarns, women’s couture clothes and mohair velours for furniture. Mohair comes into its own and is probably unequalled in brushed fabrics (also called ‘candy floss’ mohair in certain cases) and plush and velour fabrics. As early as the 1870s, imitation furs, using mohair pile fabrics, were manufactured,22 and mohair plush for upholstery was already popular by the 1890s. Mohair was used as automobile upholstery and rugs, and as upholstery in railway carriages more than 60 years ago,23 and in 1924 America had all its automobile upholstery made from mohair.17 Mohair pile furnishing fabrics were already very popular over 70 years ago.17 Before the Second World War, ‘uncrushable’ mohair velvet was already being made. Mohair has traditionally found outlets in plush and pile fabrics (e.g. velours in furnishings and upholstery), hand-knitting, men’s suitings, blankets, rugs and garment linings. Its lustre, resilience, smoothness, hard wearing and crease-resistant properties make mohair valuable for upholstery and any pile fabric (e.g. plush, velvet and moquettes) and it is virtually unsurpassed for general durability, recovering very quickly after being crushed. The smooth fibres do not allow dirt to collect readily, and stains are generally fairly easily removed. Mohair blends very well with other fibres and is usually used in this form.
2.6.2 The International Mohair Association The International Mohair Association (IMA) was formed on 21 November 1974 for the purpose of promoting the use of mohair, protecting its members against unfair competition and trade malpractice and to ensure the maintenance of the highest quality standards associated with this luxury fibre.292 It is funded by its members who come from agriculture, commerce and industry, the IMA consisting of various product groups. It is split into National Committees depending on geographical area.
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Originally the most important functions of the IMA were reported to be the promotion of mohair internationally, the collection and dissemination of market information and the running and support of the Mohair Laboratories (Mohairlabs) and Mark schemes and labelling, the IMA owning the International Mohair Mark. All parties with interests in mohair were brought together into a single organisation with the main purpose of promoting the image of mohair and its uses as a speciality textile fibre. The membership of the IMA is divided into two sections, namely growers and users. The IMA created a forum for all parties to discuss their mutual interests and problems and to exchange ideas, from which a very sound understanding resulted to the benefit of everybody concerned. Much confidence and stability were engendered through the advent of the IMA. This was apparent throughout the trade.293
2.6.3 The Mohair Mark The International Mohair Association (IMA) Mohair Mark was introduced in 1976, and in 1999 registered in 35 countries. It is shown in Fig. 2.18. A Diamond Mark, for woven fabric containing a 100 % mohair weft, was introduced in 1988 but was subsequently dropped. Furnishing velours with 100 % mohair pile, irrespective of the backing, are promoted under the Gold Label system, the Silver Mark being allocated to goods with a minimum pile content of 70 % mohair. Finished woollen goods, such as stoles, blankets, scarves with a minimum mohair content of 70 %, have a Silver rating, while women’s piece goods, for apparel manufacture, must contain a minimum of 40 % mohair to qualify for promotion.294 A minimum of 70 % mohair is required for the IMA Gold Mark in hand-knitting yarns,295 with at least 40 % for a Silver Mark.295 The rules for the use of the mohair trade mark are set out in Appendix 8.
2.18 The Mohair Mark.
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2.6.4 Mohairlabs In order to achieve better and more consistent fibre diameter and length test results worldwide, the IMA Mohairlabs Association was formed in 1984. It now runs annually international interlaboratory round trials on the basis of which the right to use a Mohairlabs stamp is awarded to those laboratories that achieve the prescribed accuracy.292 Mohairlabs was formed with the following purpose, aims and membership. Purpose The purpose of the Association is not to conflict with already established Textile Testing Associations (such as Interwoollabs) but recognizes the need for specialist knowledge and expertise necessary for accurate testing of mohair, due to certain fundamental differences between wool and mohair. The most significant of which is the much greater variation in fibre diameter inherent to mohair. Aims The aims of the Association are: 1
2 3 4 5
To develop co-operation between member laboratories with the view to standardisation of test methods, in order to achieve correct and uniform test results on mohair. To promote the confidence of all processors and users of mohair, in the accuracy and integrity of member laboratories’ test results. To assist all interested parties in resolving disputes arising from differences in test results. To undertake to investigate and establish standard rules for any aspect of mohair testing which may from time to time become necessary. The method of application of the aims is defined in the Rules of the Association.
Membership 1
2
The Association shall be open to all suitably equipped Textile Testing Houses, which have applied to, and complied with, the entrance requirements and who agree to abide by the Rules of the Association as administered by the Technical Committee. Membership of the Association does not imply full membership of the International Mohair Association.
2.6.5 Environmental, health and safety issues Angora goats feed on, and control, vegetation such as shrubs and thorn bushes, often in areas not very suited either to other domestic animals or
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to the cultivation of food or other crops. Therefore, in this respect, they play a positive role from an environmental point of view. They do, however, require some chemical controls in the form of pesticides, for example dips for lice. Such pesticides can represent an environmental hazard, for example polluting scouring effluent. To combat this, countries such as South Africa have banned the use of the very harmful classes of pesticides, notably the organo-chlorides (OCs) and arsenic compounds. Presently the organophosphates, used as dips, are also increasingly coming under the spotlight and more environmentally acceptable alternatives are being developed and introduced. To combat the problem further, certain countries have also introduced monitoring programmes. In addition to the possible hazards posed by the pesticide residues in effluent, mohair scouring and carbonising plants also produce polluting effluents but today these are generally very effectively treated as in the case of wool. Beyond this, mohair can be regarded as an eco-friendly fibre, provided appropriate dyestuffs and other chemicals are used during processing, including mothproofing. From the point of view of health and safety, mohair, in common with other animal fibres is generally very comfortable and it is rare that any allergic reaction to it occurs, although there are very occasionally problems with prickliness or scratchiness when the fibre comes into direct contact with the skin. These can be minimised by increasing the length of the fibres protruding from the fabric surface, by using the finest mohair possible and by applying a softening treatment to the fibre. The softening process is receiving increasing attention because it could extend greatly versatility and consumer acceptance provided other desirable characteristics, such as lustre, comfort and durability, are not deleteriously affected. The low flammability of mohair renders it useful in several applications that have been detailed in Section 2.4.9.2.
Acknowledgements The authors would like to express their appreciation to Mrs L Dorfling for her valuable assistance in preparing the text.
References 1 Von Bergen W, Speciality Hair Fibres, Von Bergen’s Wool Handbook, Vol.1, 315, New York, Interscience Publishers, 1969. 2 Hunter L, Mohair: A Review of its Properties, Processing and Applications, The CSIR Division of Textile Technology, Port Elizabeth, International Mohair Association and The Textile Institute, 1993.
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197 Wang X, Chang L and Wang L J, ‘Evaluating the relationship between the coefficients of variation of single fibre strength and fibre diameter’, J Text Inst, 1999, 90 (Part 1, No. 3), 456. 198 Turpie D W F and Steenkamp C, ‘Part I: Introduction and calibration using a new procedure’, IWTO Rep. No. 8, Perth, Australia, 1989. 199 Turpie D W F, Steenkamp C, Lüpke E E, Kritzinger N M and Lupton C, ‘Part II: Trials with wool tops’, IWTO Rep. No. 9, Perth, Australia, 1989. 200 Turpie D W F, Steenkamp C, Lüpke E E, Kritzinger N M and Lupton C, ‘Part III: Trials with mohair tops containing various levels of kemp’, IWTO Rep. No. 10, Perth, Australia, 1989. 201 Turpie D W F and Steenkamp C H, ‘A comparison of declared diameter distribution characteristics of wool and mohair calibration tops with actual results obtained on the FDA using both “Manual” and “Automatic” calibration techniques’, IWTO Rep No. 1, Nice, 1990. 202 Blankenburg G, Philippen H, Spiegelmacher P and Hahnen J, ‘Correlation of the fibre ellipticity, snippet length and embedding medium with the mean diameter of mohair and wool’, IWTO Rep No. 3, Nice, 1992. 203 Anon, ‘Mohair top standards’, WIRA News, 1972, 21, 8. 204 Anon, ‘Standard specification for fineness of mohair top and assignment of grade’, ASTM, 1976, Part 33, 226. 205 Anon, ‘Standard specifications for fineness of mohair top and assignment of grade’, ASTM 1976, Part 33, 624. 206 Anon, ‘USDA grade standards for grease mohair and mohair top’, USDA, Marketing Bulletin, 1977, 62. 207 Anon, ‘Standard specifications for fineness of wool or mohair and assignment of grade’, ASTM D3991-81, 1981, Part 33, 792. 208 Anon, ‘Standard test method for diameter of wool and other animal fibres by microprojection’, ASTM D2130-78, 1983. 209 Anon, Standard Test Method for Diameter of Wool and Other Animal Fibers by Microprojection, ASTM D2130-88, 1988, Part 33, 382. 210 Cizek J and Turpie D W F, ‘The performance and application of the SAWTRI Length/Strength tester for raw wool’, Proc Int Wool Text Res Conf, Vol.II, 137 Tokyo, The Society of Fiber Science and Technology, 1985. 211 Turpie D W F and Cizek J, ‘Further studies involving the SAWTRI Length/Strength tester’, SAWTRI Techn Rep, No. 572 (and IWTO Rep. No. 9, Barcelona), 1985. 212 Turpie D W F, Strydom M A and Cizek J, ‘The automatic measurement of the length, strength and profile of raw wool staples and their relevance to textile processing’, Proc 2nd World Merino Conf, Vol. 3, 234, Madrid, 1986. 213 Turpie D W F, ‘Rapid estimation of fibre length distribution in wool staples by means of information provided by the SAWTRI Length/Strength tester’, IWTO Rep, Oostende, 1986. 214 Turpie D W F and Cizek J, ‘Rapid estimation of fibre length distributions in wool staples by means of information provided by the SAWTRI length/strength tester’, SAWTRI Techn Rep, No. 596, 1987. 215 Terblanche E le F, ‘An investigation into Angora goat farming in the RSA (Part 3)’, Angora Goat & Mohair J, 1990, 32(1), 25. 216 Van Der Westhuysen J M, ‘Mohair as a textile fibre’, Proc III Int Conf on Goat Production and Disease, 264, Tucson, Arizona, 1982.
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217 McGregor B A, ‘How mohair is valued’, Austr Angora Mohair J, 1990, 7(2), 13. 218 Wood W J, ‘How to spin mohair’, Text Ind, 1956, 120(9), 151. 219 Villers M, ‘A Historical Survey of Mohair Manufacture’, MA Thesis, Unversity of Leeds, 1960. 220 Kriel W,‘Pilot plant studies on mohair scouring, Part I: Influence of rate of backflow’, SAWTRI Techn Rep, No. 29, 1964. 221 Kriel W J and Grové C C, ‘Pilot plant studies of mohair scouring’, Text Rec, 1966, 83, 59. 222 Turpie D W F and Musmeci S A, ‘A preliminary note on the centrifugal treatment of mohair scouring liquors’, SAWTRI Bull, 1976, 10(1), 26. 223 Anon, ‘Progress in mohair yarn production’, Text Rec, 1962, 80(954), 64. 224 Grové C C and Albertyn D, ‘Pilot plant studies on mohair scouring, Part III: A further study on some factors influencing detergent consumption’, SAWTRI Techn Rep, No. 56, 1965. 225 Mozes T E and Turpie D W F, ‘Treatment of wool scouring liquors, VI: Initial studies on hollow fibre pilot scale ultrafiltration’, SAWTRI Techn Rep, No. 349, 1977. 226 Mozes T E and Turpie D W F, ‘The particle size distribution of suspended solid dirt in a range of industrial raw wool, mohair and karakul aqueous scouring wastes’, SAWTRI Bull, 1979, 13(2), 43. 227 Mozes T E, ‘The treatment and purification of wool and mohair scouring wastes – a survey’, SAWTRI Special Publication, WOL 58, 1982. 228 Townsend R B, Neytzell-De Wilde F G, Buckley C A, Turpie D W F and Steenkamp C H, ‘Dynamic Membrane Treatment of Industrial Effluents: A Situation Report on the Application of the Technique in Wool Scouring and Textile Dyeing Industries’, SAMSIG Symp Dynamic Membrane Applications Update, Wilderness, South Africa, 1989. 229 Turpie D W F, Steenkamp C H and Townsend R B, ‘Industrial application of formed-in-place membrane ultrafiltration and automated membrane-forming in the treatment and re-cycle of rinse-water during the scouring of raw wool’, Wat Sci Tech, 1992, 25(10), 127. 230 Turpie D W F, Steenkamp C H and Townsend R B, ‘Industrial application of formed-in-place membrane ultrafiltration and automated membrane-forming in the treatment and re-cycle of rinse-water during the scouring of raw wool’, Conf Membrane Technology in Wastewater Management, Cape Town, 1992. 231 Pfeiffer F A, Lupton C J, Blakeman N E and Jenkins R F, ‘Spraying oleic acid on Angora goats for reduction of vegetable matter contamination’, Sheep and Goat, Wool and Mohair (1988 – Research Reports), 1988, 49. 232 Von Bergen W, ‘Wool and mohair’, Amer Dyest Rep, 1937, 26, 271. 233 Turpie D W F, ‘An introductory study on the mild carbonising of raw wool and mohair’, IWTO Rep, Rio de Janeiro, 1987. 234 Turpie D W F, ‘Studies on the mild carbonizing of raw wool and mohair, Part I: Some laboratory studies together with processing results on the worsted system’, SAWTRI Techn Rep, No. 597, 1987. 235 Turpie D W F and Godawa T O, ‘Production of tops from very seedy mohair with and without carbonizing’, SAWTRI Techn Rep, No. 213, 1974. 236 Srivastava T V K, ‘Process development in speciality processing with particular reference to mohair’, Textile Machinery Accessories & Stores, 1984, 20(6), 25.
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237 Cilliers W C and Turpie D W F, ‘Mohair processing – SAWTRI at your service’, Angora Goat & Mohair J, 1969, 11(1), 7. 238 Grobler M C, ‘Mohair in the nineties’, Austr Angora Mohair J, 1991, 8(1), 27. 239 Hibbert T W and Laycock H W, ‘Mohair and its uses’, Bradford Text Soc J, 1970, 22. 240 Hibbert T W, ‘Promising outlook for mohair’, Wool Rec, 1971, 119, 4. 241 Parkin W and Blackburn G H, ‘Influence of roving storage on the spinning performance and properties of some mohair yarns’, Proc Int Wool Text Res Conf, Vol. III, 565, Pretoria, 1980. 242 Hibbert T W, ‘Mohair spinning’, Angora Goat & Mohair J, 1971, 13(2), 13. 243 Veldsman D P, ‘Tryptophane content of weathered wool and mohair and morphologically deviated wool’, Chem & Industr, July 4, 1959, 878. 244 Blackburn G H, ‘Influence of roving storage on the spinning performance and properties of some mohair yarns’, Index of Thesis, ASLIB XXV, Part 2, Bradford University, 1977. 245 Parkin W and Blackburn G H, ‘The influence of roving storage on the spinning performance and properties of some mohair yarn’, Proc Int Wool Text Res Conf, Vol. III, 565, Pretoria, 1980. 246 Turpie D W F and Hunter L, ‘The spinning potential and yarn hairiness of a selection of mohair types spun on a ring frame’, SAWTRI Techn Rep, No. 368, 1977. 247 Strydom M A, ‘The processing characteristics of South African mohair, Part I: Long, medium and short, good to average style Kids, Young Goats and Adults’, SAWTRI Techn Rep, No. 488, 1981. 248 Goen J P, ‘A Study of the quality of fabric made from Texas natural fibers produced from yarn spun on various spinning systems: Conventional, open-end, worsted and self-twist’, Annual Progress Report to the Natural Fibers & Food Protein Comm of Texas, Vol. 1, 121, 1982. 249 Strydom M A, ‘The processing characteristics of South African mohair, Part II: A comparison of summer and winter hair’, SAWTRI Techn Rep, No. 532, 1983. 250 Strydom M A, ‘The processing characteristics of South African mohair, Part III: Blends of types differing in length’, SAWTRI Techn Rep, No. 533, 1983. 251 Strydom M A and Gee E, ‘The effect of fibre properties on the topmaking and spinning performance of Cape mohair’, Proc Int Wool Text Res Conf, Vol. II, 75, Tokyo, The Society of Fiber Science and Technology, 1985. 252 Turpie D W F, ‘Effect of fibre diameter on mohair spinning’, Wool Rec, 1986, 145(3498), 63. 253 Hunter L and Dorfling L, ‘Influence of Angora goat age on the topmaking performance of mohair’, Mell Textilber, 1994, 75, 878 & E225. 254 Hunter L, Smuts S and Dorfling L, ‘Influence of style and character on the textile performance of Cape mohair’, Mell Textilber, 1997, 78, 221 & E45. 255 Hunter L and Dorfling L, ‘The effect of Angora goat age on mohair processing performance’, Report to IMA (unpublished), 1992. 256 Minikhiem D L, Lupton C J, Pfeiffer F A and Marschall J R, ‘Effects of style and character of U.S. mohair on top properties’, Sheep & Goat Res J, 1995, 11(2), 54. 257 Turpie D W F, ‘Some of SAWTRI’s important research findings on mohair’, SAWTRI Special Publication, WOL 69, June 1985.
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258 Smith G A, ‘Processing of speciality animal fibres’, Proc 1st Int Symp Speciality Animal Fibers, DWI 103, 8, Aachen, Deutsches Wollforschungsinstitut, 1988. 259 Anon, ‘Mohair demand strong and prices firm’, Wool Rec, 1983, 142(3469), 14. 260 Metchette G, ‘Spinning fancy yarns’, Shuttle, Spindle and Dyepot, 1982, 14, 17. 261 Anon, ‘Repco research results impress world experts’, SA Text, 1977, 25(10), 13. 262 Robinson G A and Turpie D W F, ‘New developments in fabric manufacture’, Symp New Develop Fabric Manuf, Port Elizabeth, SAWTRI, 1977. 263 Marsland S G and Turpie D W F, ‘A note on the production of mohair-based slub yarns on the Repco spinner’, SAWTRI Bull, 1976, 10(2), 33. 264 Turpie D W F, Marsland S G and Robinson G A, ‘Production of mohair yarns on the Repco spinner, Part I: Some preliminary spinning trials’, SAWTRI Techn Rep, No. 296, 1976. 265 Robinson G A, Marsland S G and Ellis R, ‘Production of mohair yarns on the Repco spinner, Part II: The spinning of wrapped core-spun mohair yarns and their use in lightweight mohair suiting fabrics’, SAWTRI Techn Rep, No. 335, 1977. 266 Robinson G A, Hunter L and Taylor H, ‘Spinning and weaving of DREF yarns having speciality fibres on the surface’, SAWTRI Techn Rep, No. 493, 1981. 267 Hunter L, Smuts S and Kelly I W, ‘The effect of fibre diameter on the wrinkling and other physical properties of some all-mohair and mohair/wool woven fabrics’, SAWTRI Techn Rep, No. 446, 1979. 268 Hunter L, Smuts S and Turpie D W F, ‘The effect of certain mohair fabric properties on yarn and fabric properties’, Proc Int Wool Text Res Conf, Vol. IV, 67, Pretoria, 1980. 269 Hunter L, Smuts S and Gee E, ‘The effect of mohair fibre properties on yarns and fabric properties’, Proc Int Wool Text Res Conf, Tokyo, Vol. II, 105, 1985. 270 Hunter L and Kruger P J, ‘A study of the lubrication of mohair (Part I)’, SAWTRI Techn Rep, No. 159, 1972. 271 Galuszynski S and Robinson G A, ‘Performance of mohair/wool worsted suiting fabrics during making-up’, SAWTRI Techn Rep, No. 599, 1987. 272 Carnaby G A, Kawabata S, Niwa M and Walls R J, ‘The development of tropical fabrics containing New Zealand wool’, WRONZ Report, No. R119, 1984. 273 Kawabata S, Carnaby G A and Niwa M, ‘New Zealand/Japan joint project for developing high quality summer suitings using New Zealand wool and fabric objective measurement technology’, WRONZ Special Publ, Vol. 6, 92, 1988. 274 Fujiwara H, ‘Study on the improvement of the quality of wool fabrics (Japanese)’, J Text Mach Soc, 1983, 36(3), 171. 275 Fujiwara H, ‘A study on the improvement of wool fabric quality’, J Text Mach Soc Japan, 1987, 33(3), 78. 276 Curiskis J I, ‘Fabric objective measurement: 5, Production control in textile manufacture’, Text Asia, 1989, 20(10), 42. 277 Postle R, ‘Fabric objective measurement: 6, Product development and implementation’, Text Asia, 1989, 20(10), 59. 278 Niwa M, Kawabata S, Kurihara S and Carnaby G A, ‘Analysis of the handle of high quality tropical fabrics developed using New Zealand wool in a joint New Zealand/Japan project’, Proc Int Wool Text Res Conf, Vol. V, 350, Christchurch, Wool Research Organisation of New Zealand, 1990. 279 Smuts S, Lee J and Hunter L, ‘A review of fabric objective measurement’, TexReport No. 3, 1991.
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280 Hunter L, Smuts S, Leeuwner W and Frazer W, ‘The effect of various fibre, yarn and fabric parameters on the wrinkle recovery of wool and mohair fabrics’, Proc Japan–Australia Joint Symp on Obj Measurement, Kyoto, 65, Osaka, Textile Machinery Society of Japan, 1985. 281 Outram E E H, ‘The latest mohair trends in the Far East’, Angora Goat & Mohair J, 1990, 32(2), 59. 282 Keighley M, ‘Winning ways with worsted yarns’, Wool Rec, 1984, 143(3482), 22. 283 Swanepoel O A, ‘Factors in dyeing wool and mohair’, Text Month April 1968, 84. 284 Veldsman D P, From Mohair Fleece to Fabric, SAWTRI Special Publ, Port Elizabeth, 1969. 285 Roberts M B and Gee E, ‘Some observations on the dyeing characteristics of mohair relative to Corriedale wool’, SAWTRI Bull, 1977, 11(3), 32. 286 Gandhi R S,‘The set/supercontraction characteristics of oxidised keratin fibres’, PhD Thesis, University of Leeds, 1965. 287 Kidd F, ‘Other animal fibers’, in Chemistry of Natural Protein Fibers, Asquith R S (ed), 371, New York, Plenum, 1977. 288 Grenner D and Blankenburg G, ‘Setting in the production of crimped yarns – study of fibre damage in industrially set crimped wool and mohair yarns and the influence of pH on setting I’ (German), Textil-Praxis, 1971, 26, 364. 289 Grenner D and Blankenburg G, ‘Schonende fixierung beim Erzeugen von Kräuselgarnen’, Textil-Praxis, 1972, 27, 50. 290 Masters A, ‘Adult mohair under the microscope’, Angora Goat & Mohair J, 1999, 41, 15. 291 Buxton A, ‘Luxury fibres’, Text Outlook Int, 1986 (November), 67. 292 Romer W, ‘Mohair comes in for scientific scrutiny’, Austr Angora Mohair J, 1988, 5(5) 19. 293 Hobson D A, ‘Mohair benefits from marketing system’, Wool Rec, 1983, 142(3465), 49. 294 Anon, ‘Mohair heads out on the campaign trail’, Wool Rec, 1976, 130(3386), 34. 295 Knight A C, ‘Mohair on the march’, Wool Rec, 1980, 138(3433), 65. 296 Friedlin R, ‘The first new natural fiber for 100 years’, Wool Rec, 1987, 146(3517), 53. 297 Friedlin R, ‘Cashgora: A natural choice for the 90’s’, Int Text, 1990, 716, 18. 298 Albertin J, Souren I and Rouette H-K, ‘Cashgora or cashmere?’, Textil-Praxis, 1990, 45, II & 719. 299 Engelbrecht J, ‘The dangers of short and coarse mohair’, Angora Goat & Mohair J, 1987, 29(1), 53. 300 Springhall S, Woodward J and Sinclair A, ‘New Zealand cashgora – the fibre and its marketing’, Proc Int Wool Text Res Conf, Vol. II, 327, Christchurch,Wool Research Organisation of New Zealand, 1990. 301 Ross T, ‘Cashgora – a new fibre for the luxury market’, Wool Rec, 1984, 143(3476), 21. 302 Anon, ‘Positive view taken of cashgora prospects’, Wool Rec, 1990, 149(3546), 37. 303 Friedlin R and Petit M, ‘Cashgora, the first new natural textile fiber of the last 100 years’, Proc 1st Int Symp Speciality Animal Fibres, DWI 103, 1, Aachen, Deutsches Wollforschungsinstitut, 1988.
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304 Phan K-H, Wortmann F-J and Arns W, ‘On the morphology of Cashgora fibre’, Proc Text Conf, DWI 105, 135, Aachen, Deutsches Wollforschungsinstitut, 1990. 305 Phan K-H, Wortmann F-J and Arns W, ‘Cashmere! Cashmere?’, Proc Text Conf, DWI 108, 235, Aachen, Deutsches Wollforschungsinstitut, 1991. 306 Tucker D J, Hudson A H F, Ozolins G V, Rivett D E and Jones L N, ‘Some aspects of the structure and composition of speciality animal fibres’, Proc 1st Int Symp Speciality Animal Fibres, DWI 103, 71, Aachen, Deutsches Wollforschungsinstitut, 1988. 307 Kirby J, ‘Fancy fibres in favour’, Text Asia, 1991, 22(6), 141.
3 Cashmere, camelhair and other hair fibres
3.1
Introduction
The fibres discussed in this chapter include cashmere, camelhair and the species of Lama, the Angora rabbit and the yak. These fibres come from animals which mostly inhabit inhospitable regions of mountains and tundra where a highly protective fleece or fur is essential for survival. Some of the animals’ habitats cover a range of altitudes and climates. Generally speaking, for a given species the higher the altitude and the sparser the food, the finer the fibre. Table 3.1 gives a comparison of fibre characteristics and production figures. The fibres’ combination of lightness and high thermal properties makes them exceptional, although some are produced in such small quantities that their contribution to the annual global tonnage is negligible. Appendix 2 provides some unusual information on spider silk, which is not a hair fibre at all but a protein that makes a transition from soluble to insoluble once it has been extruded from the spider. The difficulties of harvesting the fibre are being overcome in a novel manner, and we hope that the reader will find the appendix interesting and informative. Camelid fibres, as their name suggests, are produced by species of the camel family, the Bactrian camel (two-humped, as opposed to the Dromedary which has one hump) and the South American branch, llamas, alpacas, guanaco and vicuña. The last three, yak, musk ox and rabbit are in neither of these two groups. Apart from the Angora rabbit, all these animals live in areas where the climatic conditions are harsh, and range typically from well below freezing point at night to warm, or, in some cases, tropical conditions during the day. As a result of the extremes of temperature under which they live, they have nearly all developed hair coverings consisting of an outer coat of coarser guard hairs which protects them from the sun, rain and dust and an undercoat of finer down hair which forms an insulating layer. The only two exceptions are the alpaca and the vicuña which, like the sheep, have an 133
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Table 3.1 Luxury fibres: diameters, lengths, yield per animal, production and prices8–11,14,18,23,25 Fibre
Fibre diameter (mm)
Fibre length of down hair (mm)
Yield per animal (kg/yr)
Production (tonnes/yr*)
Price (US$/kg*)
Alpaca Angora rabbit Cashgora Camel hair Cashmere Guanaco Llama Mohair Musk ox Silk Vicuña Yak
20–36 14 18–23 18–24 12.5–19 14–16 19.38 23–40 11–20
200–550 60 30–90 36–40 35–50 30–60 80–250 84–130 40–70 Filament 30–40 35–50
3–5 0.42–0.82 50 % of fleece 3.5–5 0.10–0.16 0.70–0.95 2–5 4–10 0.9 Not relevant 0.2 0.1
4 000–5 000 3 000 50 4 500 9 000–10 0001 10 2 500–2 750 7 000 3 75 000 5 1 000
2–10 20 45 9.5–24 100–130 150 2–4 7.5–8
12–15 15–20
22–20 360 20
* Figures current at April 2001.
entire fleece made up of one kind of fibre only. As the valuable part of the fleece is the down, in those fleeces where both guard and down hairs are present, the two types of fibres need to be separated by a process called dehairing before the down can be spun. This is done either mechanically, or, now rarely, by hand. Apart from dehairing, the spinning of these fibres follows traditional woollen processing for the shorter fibres and worsted processing for the longer fibres. However, all these fibres have smoother surfaces than wool because the outer scales of the fibres are less pronounced and more widely spaced. The crimp levels are also usually lower and in some cases are better described as curling or waviness. Fibre to fibre friction in yarn preparation and spinning will, therefore, be lower than that of wool, and carding and spinning conditions will need to be modified. Exactly what these modifications are will depend on the particular fibre or blend being processed and usually is confidential to each of the companies concerned. The dehairing process is carried out before combing or carding and separates the down from the guard fibres. Exactly how each topmaker or spinner does this is still relatively confidential to each company. Variables might include the length and diameter of the fibres to be dehaired, the number of passes through cards that the fibres are given, the carding conditions, which additives are or are not used and the type of card clothing used. As a result of past help from the Japanese, China now manufactures its own dehairing machinery, and currently dehairs and spins its own cash-
Cashmere, camelhair and other hair fibres
135
mere and camel hair, and produces its own knitwear, mainly for export so as to considerably increase the added value of their original raw material. All these fibres are keratin fibres, with chemical and physical compositions resembling those of wool. Because of their close chemical compositions, dyeing techniques, machinery and dyestuffs are similar to those used for wool, but because the smoother surfaces of these fibres reflect light differently when compared to those of wool it may be necessary to modify the dye recipes in order to obtain defined shades. The different surface structures of the fibres will also cause them to react differently during wet fabric finishing and this may require processing conditions to be modified. One major difference from wool is that most of these fibres are medullated to a greater or lesser degree and, in some cases, have microscopic air pockets within the fibre structure. This lightens the fibre and adds to its insulating properties. A certain amount of scientific interest is being generated in the possibilities and advantages of interbreeding between the different races within both the goat and camelid groups. Examples that are well known are the huarizo and misti crosses between the alpaca and llama species, and more recently, cashgora (angora and certain races of feral goats; more information is given on cashgora in Section 3.2.6). Less well known are the experimental crosses between the dromedary and the guanaco1 and between llamas and guanacos2 where the advantage is said to be that the ‘llamanacos’ have inherited the domesticity of the llama and the beige and brown colours of the guanaco. It is also interesting to note the recent development of new textile products built on both the technical advantages of these protein fibres, particularly their inherent poor flammability, and their high image, aesthetics and comfort. Dalton Lucerne Rare Fibres Ltd3 have produced, and are continuing to develop, a range of wall coverings, curtains and blinds made from several of these expensive fibres that are aimed specifically at the private aircraft and luxury yacht market. These fabrics are based on the luxury hair fibres, sometimes mixed with silk or Sea Island cotton. Research associated with this project was presented in a recent conference paper, and this can be found in Appendix 11. The paper specifically describes how the fabrics have been meeting the stringent American fire safety regulations for aircraft. The formal and authoritative identification of fibres has often been difficult, and Dr Hunter in chapter 15 of his book, Mohair: A review of its Properties, Processing and Applications,4 provides extensive coverage of recent progress in the field of qualitative and quantitative identification of what are, chemically and physically, very similar fibres. As he states, this is an area of considerable commercial and legal importance and, whilst very considerable progress has been made by using modern techniques, the fact remains that the quantitative evaluation of the constituents of a blended
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fabric containing, for example, wool and cashmere or mohair remains expensive, time-consuming and, to a greater or lesser extent, subjective, because it depends on the skill and experience of the operators. Exactly the same problems are faced with blends of certain cellulosic fibres such as cotton, viscose, linen, ramie and hemp. It is therefore regrettable that work in this field initiated by Centexbel5 in the late 1980s, using what was at that time advanced computer analysis, was abandoned due to lack of funding. Our objective in this chapter is to cover down hairs only, although the coarser guard hairs are mentioned on several occasions as many of these do have textile applications, for example for tents, ropes and blankets. However, they are not traded to any significant extent on world markets and are not luxury fibres. They are therefore not treated in any depth.
3.2
Cashmere, Pashmina and Cashgora
The cashmere goat (Capra hircus laniger) and its fibre takes its name from Kashmir, which straddles the India–Pakistan frontier in the western Himalayas. At present little fibre is obtained from that area and cashmere is now principally produced in northern China, Mongolia, Tibet and Afghanistan. Smaller quantities are also produced in the Central Asian Republics, Iran, Australia and New Zealand.5,8,12 Figure 3.1 shows the cashmere goat. The height of these goats is between 60 and 80 cm. The male weighs on average 60 kg and the female, 40 kg, although those from the Gobi desert are smaller. Their average life span is about 7 years. The fleece is open, with long coarser outer hair and underhair or down. Each goat produces between 100 and 160 g of usable down per year.8 This down is very fine (12.5–19 mm), see Fig. 3.2. It has an average length of 35–50 mm. Table 3.2 gives more information on the fibre. The fine down enables these goats to withstand the extreme winter cold of their original habitat, the plateaux of Central Asia. They protect themselves from overheating in the summer by shedding their down in the spring (see Section 3.2.1, harvesting).
3.2.1 Fibre production, harvesting and characteristics Of the world’s production of 9000–10 000 tonnes, 50–60 % comes from China including Tibet, over half of which comes from Inner Mongolia, 20– 30 % from Mongolia, and the balance from Iran and Afghanistan.5 The other countries mentioned above produce only small quantities. Production in China and Mongolia has fallen by 10 % during the past few years due to
Coarse Regular diameter, fairly prominent scale margins
Fine Fairly regular diameter, scale margins prominent
Interrupted or continuous
None
Some fibres dense and even
Some sparsely pigmented
Oval to circular, some flattened
Almost circular
Concentric
None
Medulla
Contour
Pigment distribution
Profile
Medulla
Cross-section
Whole mount
Thin
Thin
Cuticle
Dense in some fibres
Fairly even
Pigment distribution
Mid-length
Tip
Irregular waved mosaic, slightly crenate-rippled; near margins
Waved, crenate; near margins
Regular waved mosaic, smooth; distant margins
Base
Scale pattern
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Cashmere goat Capra hircus laniger
Animal
Table 3.2 Whole mount, cross-section and scale pattern of cashmere goat
3.1 Cashmere goat reproduced from Pier Giuseppe Alvigini, The Fibres Nearest the Sky, Mondadore Editore, Verona, by kind permission of Mr Pier Alvigini at Alvigini S.A.S. 13900 Biella Via Dante, 12 Casella Postale 430, Italy.
138 Silk, mohair, cashmere and other luxury fibres
Cashmere, camelhair and other hair fibres
139
25µm
3.2 Cashmere goat fibres, courtesy of Shirley Technologies, BTTG, Shirley House, Towers 2000 Business Park, Wilmslow Road, Didsbury, Manchester M20 2RB.
severe winter conditions. China is also attempting to control goat numbers because of overgrazing which causes desertification.7 In China and Mongolia, cashmere is harvested by combing during the three to six week spring period when the goats are moulting or by collecting the moulted fibres from the ground and bushes. In Iran, Afghanistan, Australia and New Zealand the fleece is usually shorn.5,8 The hair is sorted by hand for grades and colours (white, grey and brown). This is done quickly and requires considerable expertise, and reduces the amount of guard hair. After sorting, the different piles of hair are ‘willowed’, which entails putting the fibres through a simple revolving machine to shake out much of the dust and grit. After sorting and willowing the fibres are scoured before being dehaired.9 The quality of the dehaired fibre is assessed by the diameter, colour and length and the coarse hair content. Diameters are within the range of 14– 19 mm and the fibre lengths measure from 150 to 450 mm.5 Chinese cashmere is considered to be the best quality, has a fibre diameter of 14–16 mm,5 and is predominantly white. Cashmere fibres are shown in Fig. 3.2. The standard of the Cashmere and Camel Hair Institute (CCMI) of the USA is 18.5 mm ± 0.5 mm. Cashmere produced in Mongolia is generally slightly coarser than the Chinese fibre, its diameter being 16–17.5 mm. Due to cross-breeding for increased yield, some Mongolian fibre is increasing in
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Silk, mohair, cashmere and other luxury fibres
diameter, with consequent loss of quality. Cashmere from New Zealand and Australia is in the 16–18.5 mm range; that from Iran and Afghanistan in the 16–19.5 mm range.5 Experience has shown that cashmere goats raised in more benign climates do not produce such fine down as they do in their native habitat, although the fibres are still very soft when compared to many other animal fibres. For further details concerning cashmere fibres of differing origins see the paper by Phan and Wortmann presented at the 7th international conference on goats which is reproduced in Appendix 10.12
3.2.2 Prices and manufacture Fine white knitting quality cashmere is in the US$120–130 per kg range, lower qualities from US$100 to 110 per kg. This is an increase over prices in December 1998 and January 1999.7 The overriding influence on the price is the mean fibre diameter. For example, Iranian and Afghan cashmeres have diameters 2–3 mm greater than Chinese cashmere and are 40–50 % cheaper.5 Colour is also an important factor, white being the most valuable because it can be used not only as it is but can be dyed to the pastel shades which are often required for knitwear.12 Brown is the least valuable colour because it can only be dyed to dark shades. Fleeces have to be dehaired to separate the two kinds of fibres before the down fibres are spun, as with others that have both guard and down hairs. A dehairing process specifically for cashmere was developed in the 1870s by Joseph Dawson, founder of Dawson International which is still a major operator in the luxury fibre field. All hair fleeces which contain both guard and down fibres are dehaired and the process is discussed (see p. 134) as far as it can be, bearing in mind the confidentiality that still surrounds the operation. Spinning can be on either the woollen or worsted system, depending on the lengths of the fibres and the end-use envisaged. (More information is given in the section on marketing and end-uses, 3.2.4.)
3.2.3 Distribution The Chinese government’s liberalisation of the economy in the mid 1980s led to a somewhat chaotic period during which prices rose, quality dropped and it was difficult and complicated to obtain supplies. This resulted in a decrease in knitwear sold which Dawson International, a knitwear manufacturer and major buyer of fibre, estimated at 30 %. To re-establish order, both in fibre distribution and quality standards, the Chinese government instituted regulations in 1989 to raise the quality of exported commodities, backed by mandatory testing, and in 1990 established a Cashmere Foreign
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Trade Centre to manage exports. This Centre organises four trade fairs each year to sell cashmere and sets limits to export prices. In 1991 the Chinese government issued a further regulation to the effect that all textile products from China required labels of origin, could not exceed quota restrictions and could only be exported to countries which had signed bilateral trading agreements.13 However, with the general opening up of Chinese trade, the cashmere market is no longer controlled, and the buying and selling of cashmere is now open to everyone. The physical distribution of the fibre is similar to that of camelhair but with the difference that many Chinese companies produce cashmere knitwear and distribute that globally.7 There is also an internal market for cashmere knitwear in China.5
3.2.4 Marketing and end-uses The largest part of fibre production is used in fine woollen spun yarns for knitwear in Scotland, knitted on fully fashioned frames. Both woollen and worsted yarns are used for woven fabric. Cashmere is frequently blended with fine merino wools to produce softer handling fabrics which are somewhat cheaper than 100 % cashmere but still have some of the cashmere ‘image’. Until fairly recently the two principal manufacturing countries of these high-priced articles were Scotland and Italy, but in the late 1980s China and Mongolia set up their own spinning and knitting operations using dehairing technology which they had developed in co-operation with Japanese companies.12 They increased production and although the knitwear produced was not as good in quality as the Scots and Italian merchandise, it was cheaper. However, luxury markets such as these depend not only on good marketing and on the quality of the goods provided but also, to some extent, on their scarcity value. The market was, therefore, disrupted but in addition, as the supply of cashmere fibre is limited, Scots and Italian manufacturers experienced difficulty in obtaining adequate quantities of quality raw material. European manufacturers responded by setting up joint ventures with Chinese partners in China. To a large extent this solved the supply problem, and the quality is currently being raised by improvements to Chinese production methods.5 Scots manufacturers are also defending their markets by expanding further their product lines and developing their retail networks and promotion.13 For further information and, in particular, a more detailed account of developments in the cashmere trade between 1990 and 1996 due to developments within China, see ‘Scotland and China and the Cashmere Trade’ by Theresa Purcell, reproduced in Appendix 9.
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With such highly priced and high image products it is scarcely surprising that adulteration occurs, where cashmere is blended with wool or other fibres.12 The CCMI’s policy in this area is to buy articles on the open market and analyse them in order to establish whether their fibre content is in keeping with the label on the garment.8 Cashmere garments and fabrics are mainly manufactured in the United Kingdom and Italy but there are also three companies in the USA which specialise in this niche market. Cashmere garments are distributed throughout the world but, as with many luxury products, the major markets are the USA, Japan and western Europe.5 Although less important than knitwear, woven fabrics for men’s and women’s outerwear is also an important outlet. Again, the principal consumer markets are the USA, Japan and western Europe. The outer guard hairs are used in carpets and underfelts.9
3.2.5 Pashmina The name ‘pashmina’ seems to be used rather loosely, and it is sometimes difficult to separate myth from fact regarding the origins of the fibre. Pashmina has, on occasion, been claimed to come from the ibex, but that is unlikely and it is generally accepted to be fine quality Indian cashmere. Originally, pashmina shawls and scarves were produced in Kashmir from hand-spun and woven fine cashmere fibre that was gathered from the ground and bushes where the goats had been feeding. India is not a significant producer of cashmere fibre but in Kashmir there are shawls of great fineness and softness which have been in families’ possession for generations, and many such shawls are still produced locally. These articles are expensive, even by cashmere standards, but are now available on European and American markets. Some, but not all, alleged pashmina shawls on the market contain wool, and some, described as pashmina, actually originate from areas other than Kashmir but are sold by suppliers who use the words pashmina and cashmere synonymously. This has naturally led to a certain amount of confusion in the market place!
3.2.6 Cashgora Cashgora is the name given to the fibre produced by cross-breeding the Angora goat (producer of mohair) with another type of goat. It is difficult to be specific about what type of goat because the following are mentioned in the literature: feral goats in New Zealand, cashmere goats,12 the AngloNubian and dairy goats.10 It is not surprising, therefore, that the fibre has a mixed reputation in the industry because with such varied parents its characteristics are unlikely to be constant.
Cashmere, camelhair and other hair fibres
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Cashgora raised a considerable amount of interest in the industry in the last half of the 1980s and, possibly because of this reason, in 1988 the International Wool Textile Organisation accepted ‘cashgora’ as a generic term for fibres produced by the mohair–cashmere cross. The author is indebted to Dr L Hunter for the following information about this fibre and its uses. Length, 30–90 mm24,25 (the goats are shorn twice a year); diameter, 18–23 mm. The down represents approximately 50 % of the mass of the fleece. Dr Hunter also indicates that Phan et al. examined the morphological features of the fibres and are of the opinion that they are closer to mohair than cashmere but that some fibres possess cashmere-like features (cylindrical and semi-cylindrical scales) and others some characteristics of mohair with ‘splits’, lance-shaped scales and subscales.26,27,28 The fibres have a low level of lustre. There are three types of cashgora, ranging from that at the top end (18.5 mm), marketed as ‘Ligne Or’, that at the medium range (20 mm), marketed as ‘Ligne Emeraude’ and cashgora at the lower range (22 mm), marketed as ‘Ligne Saphir’.29 At René Friedlin, the French dehairer, cashgora is classified into three classes according to diameter: 17–18.5 mm, 19.5–21 mm and 22–23 mm.30 In April 2001 the price for 20 mm cashgora was US$45/kg.6 Cashgora was used in many articles of clothing (light-weight suits and jackets, coats, scarves, stoles);26 with the exception of underwear and socks it is considered more suitable for weaving than for knitting.30 Albertin et al.31 compared the behaviour of cashgora and cashmere during finishing operations. The market’s initial enthusiasm for the new fibre was not maintained; while in 1990 global production was estimated at 200 tonnes, in 2000 it was estimated at 60 tonnes.6
3.3
Camelhair
The Camelus is part of the Caelidae grey family. Practically all camelhair is produced from the two-humped Bactrian camel which is found mainly in Mongolia and Northern China, in areas bordering on the Gobi desert where the camel feeds on the bitter vegetation rejected by other species and is illustrated in Fig. 3.3. It is very partial to salt, and will happily drink from salt lakes and brackish water. As with other animals that produce textile fibres, with the notable exceptions of sheep, alpaca and the Angora goat, the camel grows two kinds of hair, an outer protective coat of coarse (guard) hair and an insulating undercoat of fine hair or down. The down produced by camels living in the hotter desert areas tends to be coarser and sparser than from those living in more temperate areas. Some camelhair is also produced in Tibet, Afghanistan,
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3.3 Bactrian camel reproduced from Pier Giuseppe Alvigini, The Fibres Nearest the Sky (2nd ed. 1984), Mondadori Editore, Verona, by kind permission of Mr Pier Alvigini at Alvigini S.A.S. 13900 Biella – Via Dante, 12 Casella Postale 430, Italy.
Iran, Russia, New Zealand and Australia.8,9 The Bactrian camel is used as a means of transport for people and goods, occasionally for sport as well as a source of textile fibres.
3.3.1 Fibre production, characteristics and harvesting World production has been documented in the past at 4500 tonnes of greasy hair7 (other estimates put present production somewhat lower, at 3000– 3500 tonnes6). Production is evenly divided between China (Inner Mongolia, Xinjiang, Gansu and Ningzia)5 and Mongolia, and has been decreasing over the last decade, principally because, in Mongolia, Bactrian camels are being replaced by motor transport as carriers of goods.6 Fibre colours range from pale reddish to light brown, Chinese hair tending to be lighter in shade and finer than Mongolian hair.9 White fleece is the most valued but is very rare. The camel moults in late spring or early summer when the fibres form matted tufts which hang down from the head, sides, neck and legs. The fibres are harvested by pulling or by gathering the clumps shed onto the ground. Fibres are also obtained by shearing but the hair covering the humps is not shorn as this may make the animals more susceptible to disease.8,9 The whole mount, cross-section and scale pattern of the camel are shown in Table 3.3.
Intermediate thickness Regular diameter, smooth
Coarse [Guard] Regular diameter, smooth
Continuous, fine lattice
Continuous, fine lattice
Some dense, streaky
Some dense, streaky
Diffuse, sometimes streaky
Oval to circular
Oval to circular
Circular to oval
None or fragmental
Fine Regular diameter, smooth
Oval to circular
Oval to circular
Circular
Medulla
Contour
Medulla
Profile
Pigment distribution
Cross-section
Whole mount
Thin
Thin
Thin
Cuticle
Dense near medulla becoming less dense towards the cuticle Dense near medulla becoming less dense towards the cuticle
Sparse and towards the centre
Pigment distribution
Mid-length
Tip
Irregular waved, crenate-rippled; near to close margins
Irregular waved mosaic, smooth; distant margins
Irregular waved, smooth; near margins
Irregular waved, crenate; near margins
Irregular waved, crenate; near margins
Waved mosaic, smooth; near to distant margins
Base
Scale pattern
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Camel Camelus bactrianus
Animal
Table 3.3 Whole mount, cross-section and scale pattern of camel
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Silk, mohair, cashmere and other luxury fibres
After harvesting, camelhair is bought directly from the herders by middlemen who in turn sell to larger merchants and dehairers, and the hair is sorted according to colour and the age of the animal. It is then sold to private or state-run companies and eventually finds its way to spinning and weaving mills in the USA, Japan and Europe.7 The coarser fibres such as the camel manes from Mongolia and thirdgrade Chinese camel are carded on fairly coarse carding machinery, and thoroughly gilled prior to Noble combing. Owing to the large number of impurities which may not be entirely removed in scouring, a second combing process is sometimes required. The extremes of length found in this type of material usually necessitate the introduction of a ‘reducing’ process before combing. This, in effect, breaks the longer fibres to the required length, and the short tips held in the sliver are removed, together with the noil, during the combing process. Medium qualities are usually processed in the same way as alpaca but better qualities have to undergo a much finer type of carding operation, and the combing is done on a Noble comb of similar pin action to that used for Merino wool. Frequently, to achieve a greater fineness and lustre, the fibres are combed again on a Lister comb, and the large noil which represents the bulk of the finest fibres is used again as the raw material for carding and combing to produce a ‘superfine top’. Dehaired down fibre diameters range from 16 to 20 mm, intermediate hairs from 20 to 29 mm and guard hairs from 30 to 120 mm. Baby camelhair, which is the finest and the softest, has a diameter of about 16–17 mm (see Fig. 3.4). Fibre lengths of down fibres range between 36 and 40 mm,5 and guard hairs can reach up to 37.5 cm. The length of baby camelhair is similar to that of adults.9 The average yield of an adult female’s under hair is 3.5 kg, of a male’s, 7 kg.9 Prices for dehaired, knitting grade down hair are around US$24 per kg, dehaired first weaving grade down around US$12–13 per kg, and dehaired second weaving grade qualities are around US$9 per kg.5
3.3.2 End-uses The colour range is limited by dyeing to mid- and darker shades although most fabrics are produced in the fibres’ natural colour, known as ‘camel’. Some is dyed to a darker shade of brown. The principal end-uses are overcoatings and jacket weights.5 The principal manufacturing and consumer market is the USA, which accounts for 70 % to 75 % of fabric production.7 Some camelhair and camelhair-blended fabrics are also produced in the UK, Italy and Japan. In Europe the finer qualities of camelhair are also used, to some extent, in knitwear, mainly for men. A market is developing in Italy for baby camelhair as an alternative to cashmere in knitted garments10 but knitwear accounts for only a very small share of the total market.
Cashmere, camelhair and other hair fibres
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50µm
3.4 Camel fibres, courtesy of Shirley Technologies, BTTG, Shirley House, Towers 2000 Business Park, Wilmslow Road, Didsbury, Manchester M20 2RB.
Within the areas of fibre production, guard hairs are used for ropes, tentings, carpet backing, bedding and heavy outer garments. The traditional tents and outer garments used by the nomadic peoples of Central Asia are made from felted outer hair 9,10 or wool.
3.4
Alpaca fibre
The alpaca (Lama pacos) were domesticated in the altiplano some 6000 years ago for their meat and for their fibres. Adult alpaca weigh about 65 to 80 kg and grow to 90 cm tall (see Fig. 3.5). They live for up to 20 years and are productive for about 10. Unlike most other mammals from which luxury fibres are obtained, but like the Angora goat (which supplies mohair) and of course sheep, the alpaca has a complete fleece and does not produce both guard and down hairs.14,15,16 Their habitat is the Andean altiplano, at altitudes of between 3000 and 5000 metres where temperatures vary from – 25 °C at night to +18 °C during the day.17
3.4.1 Fibre production and prices Of the present population of approximately 4 million alpacas some 80 % are in Peru. Total annual production is between 4000 and 5000 tonnes of greasy fibre.16,17 Alpaca is by far the most important of the Camelid fibres,
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3.5 Alpaca by kind permission of Mr F.C. Wilson, The Alpaca Centre, Snuff Mill Lane, Stainton, Penrith, Cumbria.
Table 3.4 Alpaca population, 200018 Country
No. of Alpaca
Peru Bolivia Chile Argentina Ecuador USA Canada Australia New Zealand UK
3 500 000 350 000 40 000 5 000 5 000 15 000 10 000 20 000 5 000 5 000
Total
3 955 000
in both quantity and value. The average percentage of clean yield is 85–90.16 Table 3.4 shows the alpaca population for various countries. In Peru 80 % of the Alpaca production is concentrated in the southern region of Puno.9 The populations in the new countries of breeding, the USA and Australia in particular, are growing, but from a small base. The Peruvian population has been relatively static due to the economic restrictions
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on the smallholding farmers in the Andes. Most studies agree that an economically viable herd size for alpaca is around two thousand head, yet the average Peruvian farming unit only tends between ten and twenty animals.16 The different types of alpaca are: – – – –
Huacayo: This is the most common type – about 80 % of the total. Suri: Silky haired animal, with long fibres – about 10 % of the population. Huarizo: A ‘mule’, the result of a crossing between a male llama and a female alpaca. Misti: A ‘mule’, the result of a crossing between a male alpaca and a female llama.16
A cria is a baby alpaca, under one year old. Alpaca fibre is soft, lustrous, fine and durable. The fibre is tubular and medulated.9,10 The fibre diameter lies between 20 mm and 36 mm.9,16 Fibre lengths after shearing are as follows: huyacaya – 25 to 30 cm; baby huyacaya – 20 to 25 cm and suri – 50 to 55 cm. Average greasy hair prices in 2000 were US$ 2 to 10 per kg.16 Table 3.5 gives various details about alpaca fibre.
3.4.2 Fibre harvesting, preparing and processing Alpacas are shorn, on average, every 18 months.16 Each animal produces approximately 3.5 kg of hair as a rule but this varies from below 3 kg for the cria to 5 kg for the adult animals. The new fibre comes on to the market in October, and the shorn fleeces are classed into ten9 colour categories – white, grey, fawn, light brown, dark brown, black, roan, brown and white, black and white and spotted (or mixed colours).17 Fleeces are separated into less than one year old cria, tui (1–2 year old), and adult. They are then sorted into (a) premier fleece (back, side, part of shoulder and rump), (b) neck, (c) oddments (apron, belly, legs), or (d) pieces (head, shankings, tail and other extreme hairy pieces) within each colour category. Premier fleeces are graded according to fineness into baby (<22 mm), extra fine (22.0–24.9 mm), medium fine (25.0–29.9 mm) and coarse (>30 mm) categories. See Fig. 3.6. Extremely coarse guard hair and kempy fleeces are also separated from the main lots.9 Fleeces that were not shorn as crias have longer fibres, while late-born crias have shorter fleeces when shorn with the older crias. Fleeces are therefore also sorted for length into short (<60 mm), medium (60–120 mm) and long (>120 mm) grades. The fibres are combed on rectilinear combs, ratio of top to noils being about 90/10.16
Coarse See Llama
Fine See Llama
Continuous fine lattice (granular appearance)
More nonmedullated fibres than in Llama
Varies from sparse to very dense, some streaky
Varies from sparse to very dense, some streaky
See Llama
See Llama
Fewer fibres with bi-partite medulla than in Llama
See Llama
Medulla
Contour
Pigment distribution
Profile
Medulla
Cross-section
Whole mount
Fairly thick
Fairly thick
Cuticle
Sparse to very dense, most dense towards the cuticle. Some very large aggregates
Sparse to very dense, most dense towards the cuticle. Some very large aggregates
Pigment distribution
See Llama
See Llama
Base
Mid-length
Scale pattern
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Alpaca Lama pacos
Animal
Table 3.5 Whole mount, cross-section and scale pattern of alpaca
Tip
Cashmere, camelhair and other hair fibres
151
50µm
3.6 Alpaca fibres, courtesy of Shirley Technologies, BTTG, Shirley House, Towers 2000 Business Park, Wilmslow Road, Didsbury, Manchester M20 2RB.
3.4.3 Markets Tops, noils, yarn woven fabric and knitwear is exported from Peru, but no fibre. These products are exported to countries and excellent yearly export statistics are provided by COMEX (External Peruvian Commerce). In 2000, the major export markets were China, Italy, the UK, Germany, and Switzerland. The total value FOB of these exports was US$63.4 million, 5754 tonnes in weight plus 34 400 m2 of woven fabric.
3.4.3 End-uses and consumer markets Alpaca’s principal end-uses are in knitwear and light-weight suitings. The major consumer markets are the USA, Japan, and Italy but it is also interesting to note that Spain, Bolivia, Colombia and the UK import substantial quantities of woven fabric, and Australia and Argentina also import substantial quantities of knitwear.
3.4.4 Fire retardancy Dalton Lucerne Rare Fibres Ltd have currently obtained grants to research the fire science of natural fibres, including alpaca, and the excellent properties of fire resistance should open up markets where high standards of
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3.7 Llama reproduced from Pier Giuseppe Alvigini, The Fibres Nearest the Sky, Mondadori Editore, Verona, by kind permission of Mr Pier Alvigini at Alvigini S.A.S. 13900 Biella Via Dante, 12 Casella Postale 430, Italy.
fire protection are required. (See Appendix 11.) Experimental cloths are being woven for the company by Bradford Industrial Museum in the UK on looms similar to those used by Titus Salt in the 1800s. With cotton, silk or polyester warps, the handle of the fabrics is exceptionally pleasing.
3.5
Llama fibre
The llama (Lama glama) is similar in build to the alpaca but is larger, averaging 1.2 cm at the shoulder and weighing around 110 kg. (See Fig. 3.7.) These animals are genetically very close and can interbreed to produce ‘mules’, the huarizo and the misti. Like the alpaca, they are domesticated and probably have been so for 6000 years. They are used to carry goods (and need no saddles to protect their backs as their fleece acts as a cushion) and are the main means of transport in the mountainous areas of Bolivia and Peru, for their meat, their hides, their hair and their dried dung which is used as fuel.10,18 Table 3.6 gives some important details about the llama and Table 3.7 their distribution. There are two types of llama – kcara, a light-fleeced animal used mainly as a beast of burden and chaku, a heavy-fleeced animal used for its hair.
3.5.1 Fibre production, preparation and harvesting In South America, where their diet is almost completely protein free, the llamas’ outer coat of guard hairs may reach 20 % of the total fleece weight.
Medulla
Continuous, ofter bi- or multipartite
Profile
Coarse Regular diameter, smooth
Whole mount
Varies from sparse to very dense, some streaky
Pigment distribution
Varies – circular, oval, triangular or polygonal
Contour
Varies – circular, bi- or multipartite
Medulla
Fairly thick
Cuticle
Cross-section
Sparse to very dense, most dense towards the cuticle. Some very large aggregates
Pigment distribution
Irregular waved mosaic, smooth; near margins
Base
Tip
Irregular waved, rippled-crenate; close margins
Mid-length
Scale pattern
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Llama
Animal
Table 3.6 Whole mount, cross-section and scale pattern of llama
154
Silk, mohair, cashmere and other luxury fibres Table 3.7 Llama population Country Bolivia Peru USA Argentina Ecuador Canada Chile Australia UK Total
No. of Llama 950 000 250 000 135 000 30 000 20 000 15 000 15 000 10 000 8 000 1 433 000
Greasy hair annual production is between 2500 and 2750 tonnes, with an average greasy to clean yield of 85–90 %.16 In the US where the animals’ food may contain as much as 15 % protein, the fleeces have little, if any, guard hairs and the average fibre diameter is lower than in Bolivia. Although usually white, the down hairs can be brown, grey or black. The fleeces may be of one colour or mixed.10,18 Whilst a method of machine shearing has been developed in Peru by R Dunick of the New Zealand Wool Board,9 hand-shearing is still common. Hair growth is normally between 70 and 100 mm per year, and fleeces weigh 2–5 kg. The animals are usually shorn every two years. Fibre lengths range from 80 to 250 mm8 and fibre diameters are in the range of 19–38 mm.16 Llama fibres are depicted in Fig. 3.8. Llama is dehaired in Bolivia as well as in Europe. The average greasy hair prices in 2000 were US$2–4.
3.5.2 End-uses Very few statistics are available from Bolivia, the major producing country. Llama fibre is used, alone and in blends, for knitwear and outerwear. The guard hairs are used for ropes, braids, carpets and some coarse clothing.16
3.6
Vicuña fibre
The vicuña (Vicugna vicugna) is the smallest of the Camelids, with a shoulder height of about 90 cm and a weight of about 50 kg. (See Fig. 3.9.) Its natural habitat lies in the semi-arid grasslands of the central Andes at altitudes of 3600–5000 metres on the snow line, an important factor in its fibre production, with average daytime temperatures of +20 °C, dropping to -15 °C at night. Its life expectancy is about 20 years. Prior to the Spanish invasion of South America in the seventeenth century, vicuña fleeces were reserved for the Inca royal family, at which time it was
Cashmere, camelhair and other hair fibres
25µm
155
10µm
3.8 Llama fibres, courtesy of Shirley Technologies, BTTG, Shirley House, Towers 2000 Business Park, Wilmslow Road, Didsbury, Manchester M20 2RB.
3.9 Vicuña reproduced from Pier Giuseppe Alvigini, The Fibres Nearest the Sky, Mondadori Editore, Verona, by kind permission of Mr Pier Alvigini at Alvigini S.A.S. 13900 Biella Via Dante, 12 Casella Postale 430, Italy.
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said that there were two million vicuñas in the high Andes. After the demise of the Incas, fibre harvesting was no longer organised and the market was supplied by killing the animals for their fleeces. Over 300 years, this led to the near-extinction of the species. In 1969, barely 5000 vicuñas were left. In 1972, the Peruvian government started strictly to enforce the laws which forbade the use of vicuña hair and the hunting of the animals. By 1987, the number of vicuñas had recovered to around 50 000, and the government agreed to a trial commercialisation of the hair in woven cloth only. In 1994, the population had risen to 66 500 and the government set up a competition to commercialise the hair in ways which would benefit the highland farming communities, the manufacturer and the government. In 1999 there were 140 000 vicuñas in Peru. It is estimated the number will have increased to 165 000 by 2000. In addition there are an estimated further 55 000 in northern Chile, Bolivia and Argentina. Providing that the ecological balance can be maintained in the highlands, there is no reason why the number of vicuñas should not return to the two million figure of the time of the Inca.
3.6.1 Fibre characteristics The fibre range is from 12 to 15 mm, averaging at 13 mm, which is amongst the finest animal hairs produced. The fibre length is in the range of 20–25 mm. Table 3.8 gives relevant statistics about the vicuña and Fig. 3.10 depicts the fibres.
3.6.2 Fibre harvesting, processing and price Vicuñas are not domesticated and the majority are in Pampas Galeras, a national reserve in the Ayacucho region of Peru’s altiplano. Today the fibre is harvested much as it was in Inca times. The animals are herded into the end of a valley with very steep sides that prevent them from escaping. Just before the closed end of the valley, nets are placed so as to form small separate areas with openings which only allow one vicuña to enter at a time. When inside these pens, the animals are sheared. The vicuña has only a low percentage of fine and usable hair in its fleece, and is shorn once every 18 months. Yields vary from 85 to 550 g, with an average of 200 g per vicuña. This fine hair comes from the area just behind the front legs of the animal. Total annual production of greasy hair is expected to be around 5000 tonnes in 2000. The lack of greater quantities is attributed to two main factors: – –
As the vicuña is not a domesticated animal, not all the population is penned for shearing every year. Fine and coarse hair are intermingled in the shorn fleece, and subsequent separation generally results in high wastage and a poor yield.
Coarse See Llama
Fine Regular diameter, scale margins protrude slightly
See Llama
Interrupted
Varies from sparse to very dense, some streaky
Varies from sparse to very dense, some streaky
See Llama
See Llama
See Llama
See Llama
Medulla
Contour
Pigment distribution
Profile
Medulla
Cross-section
Whole mount
Fairly thick
Fairly thick
Cuticle
Sparse to very dense, most dense towards the cuticle. Some very large aggregates
Sparse to very dense, most dense towards the cuticle. Some very large aggregates
Pigment distribution
See Llama
See Llama
Base
Scale pattern Mid-length
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Vicuña Vicugna vicugna
Animal
Table 3.8 Whole mount, cross-section and scale pattern of vicuña
Tip
158
Silk, mohair, cashmere and other luxury fibres
25µm
3.10 Vicuña fibres, courtesy of Shirley Technologies, BTTG, Shirley House, Towers 2000 Business Park, Wilmslow Road, Didsbury, Manchester M20 2RB.
Once dehaired, the greasy to clean yield is 65–70 %. Average greasy hair price: US$360/kg. In order to extract as much of the fine hair as possible from the shorn fleeces, a prolonged manual classification process is employed in Peru. The fibre is sent to Italy for dehairing as the appropriate machinery is not yet available in Peru. As well as being dehaired in Italy most of the vicuña fibre available is also spun and woven in that country. The fibres’ natural colour is fawn which limits the colours obtainable by dyeing, as only darker shades can be produced. Vicuña is the most expensive apparel fibre.
3.6.3 End-uses and markets Because of the length of the fibre (20–25 mm), vicuña is usually woollen spun but when blended with wool, worsted spinning becomes practicable. The woollen yarns produced currently are Tex 55-25 which are woven into suitings (430 g/m), jacketings (550 g/m), overcoatings and scarves. The principal consumer markets for the fabrics are Japan (45 %), Italy (35 %), UK (10 %) and the USA (10 %).
3.7
Guanaco fibre
The guanaco (Lama hunchus or Lama guanicoe)16 is the smallest species of llama, and being more aggressive than the vicuña, it is not domesticated. Its habitat is extremely wide and ranges from the snowline down to sea level
Cashmere, camelhair and other hair fibres
159
3.11 Guanaco reproduced from Pier Giuseppe Alvigini, The Fibres Nearest the Sky, Mondadori Editore, Verona, by kind permission of Mr Pier Alvigini at Alvigini S.A.S. 13900 Biella Via Dante, 12 Casella Postale 430, Italy. Table 3.9 Animal population, Guanaco Country
No. of Guanaco
Argentina Peru Chile
500 000 90 000 10 000
Total
600 000
from Peru to Tierra del Fuego. Adult guanaco stand at about 110 cm high. (See Fig. 3.11.)
3.7.1 Fibre harvesting, production and price The guanaco population has grown in the last two or three years by about 5 % as more commercial interest is awakened in its potential; its distribution is given in Table 3.9. The fibre is harvested in the same way as is the vicuña’s. Total greasy hair production is around 10 tonnes/yr, and greasy to clean yield is 65 to 70 %. Average greasy hair price: US$150/kg.
3.7.2 Fibre characteristics These are outlined in Table 3.10. Fibre mm range is 14 to 16 mm. Figure 3.12 shows the guanaco fibres, magnified.
Coarse See Llama
Fine Regular diameter, scale margins protrude slightly
See Llama
None, interrupted or continuous
Varies from sparse to very dense, some streaky
Varies from sparse to very dense, some streaky See Llama
See Llama
See Llama
See Llama
Medulla
Contour
Pigment distribution
Profile
Medulla
Cross-section
Whole mount
Fairly thick
Fairly thick
Cuticle
Sparse to very dense, most dense towards the cuticle. Some very large aggregates
Sparse to very dense, most dense towards the cuticle. Some very large aggregates
Pigment distribution
See Llama
See Llama
Base
Mid-length
Scale pattern
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Guanaco Llama glama huanacus
Animal
Table 3.10 Whole mount, cross-section and scale pattern of guanaco
Tip
Cashmere, camelhair and other hair fibres
a
b
c
d 3.12 Guanaco fibres: (a) fine fibre, whole mount, 200¥; (b) coarse fibre, whole mount, 200¥; (c) coarse fibre mounted in lacto-picro phenol to show granular medulla, 400¥; (d) cross-sections, 200¥. Reproduced from H.M. Appleyard. A Guide to the Identification of Animal Fibres (2nd ed. 1978), by kind permission of BTTG, Wira House, West Park Ring Road, Leeds LS16 6QL.
161
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Silk, mohair, cashmere and other luxury fibres
3.7.3 End-uses and markets Little information is available but it is clear that the end-uses will be similar to those of vicuña, as will be the markets. The principal markets for the cloths are Japan (50 %), Italy (45 %) and the UK (5 %).
3.8
Angora
The Angora rabbit9,21 (Oryctolagus cuniculus) is raised solely for its fine and soft hair, unlike other breeds which are produced for their meat and fur. The Angora rabbit is shown in Fig. 3.13. China is the principal producer and in that country the rabbits are farmed on a highly intensive small-scale factory farm system by individual farmers. Substantial quantities are also produced in France and smaller quantities in Eastern Europe and South America.
3.8.1 Fibre characteristics The Angora rabbit produces three kinds of hair: Guide hairs
100 to 110 mm long; they guide and cover the growth of the other hairs. Guard hairs 80 mm long. These have rough points that lock together, lie over the down and seal it off.
3.13 Angora rabbit reproduced from Pier Giuseppe Alvigini, The Fibres Nearest the Sky, Mondadori Editore, Verona, by kind permission of Mr Pier Alvigini at Alvigini S.A.S. 13900 Biella, Via Dante, 12 Casella Postale 430, Italy.
Cashmere, camelhair and other hair fibres Down
163
60 mm long. The diameter of 14 mm makes down one of the finest animal fibres used in textiles.
Some essential details about Angora rabbit hair are given in Table 3.11. The down fibres are very smooth, with few cuticle scales, and are depicted in Fig. 3.14. The Angora rabbit produces hairs of several colours but the strain bred for textile fibres is an albino strain that produces white fibres only. Coloured Angora rabbits are bred in India and their hair is used to produce artisanal fabrics. The hairs are all medullated (hollow) which decreases their weight by nearly 20 % when compared to wool and also increases their insulating properties.
3.8.2 Fibre production and manufacture Partly because rabbit hair is produced on small-scale farms,actual production figures are difficult to establish, but it is estimated the world production is around 3000 tonnes. France may produce around 1000 tonnes. There are three strains of the Angora rabbit, the Chinese, the French and the German. The Chinese strain supplies 95 % of Chinese and South American production. The rabbits are generally shorn every three months before the hair starts falling which causes felting. Females, as long as they are not in gestation or lactation, produce 25 % to 30 % more hair than males. Rabbit hair is a delicate fibre and care must be taken when preparing it for sale. The fibres themselves are very clean,as the rabbits produce only 2 % of their fibre weight in skin excretions, and also because rabbits clean their own fur. Nonetheless, it is necessary to remove dust and vegetable matter from the fleeces before the fibres are sorted and this is done by grooming. After the removal of this extraneous matter the hairs do not need scouring before carding. After grooming, fleeces or part fleeces with lower quality fibre are removed and the remainder sorted into 4 grades: Grade 1 Clean, free of felting, over 6 cm long (70 % of the coat). Grade 2 Clean, free of felting, under 6 cm but over 3 cm (15 % of the coat). Grade 3 Clean, felted, second cut. Grade 4 All dirty, discoloured fibre. Clean hair is essential to Angora hair production because dirty hair fetches only about 15 % of the price of first quality hair, which is cheaper than the hair from ordinary breeds. Yields of down hair show considerable variation, from 250 g to 1350 g per year, although the latter weight was produced from a genetically selected animal in an experimental station in Germany. More common commercial yields vary between 420 g and 820 g a year in China and up to 1000 g a year in France and 1200 g a year in Germany. Rearing conditions, especially the
Profile
Medulla
Whole mount
Often on cortical bridges
Medulla
Oval to Wide, rectangular mostly uni-serial, some multiserial
Pigment Contour distribution
Cross-section
Thin
Cuticle
None to very dense
Pigment distribution
Irregular petal, or shallow irregular waved mosaic, smooth; near margins
Base
Scale pattern Tip
Single or double chevron or Double Single chevron chevron Æ interrupted streaked wave
Mid-length
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Fine Rabbit Fairly Ladder Oryctolagus regular cuniculus diameter, scale margins prominent
Animal
Table 3.11 Whole mount, cross-section and scale pattern of rabbit
a
b
c
3.14 Rabbit fibres: (a) rabbit, fine fibre, whole mount showing ‘air’filled medulla, 400¥; (b) rabbit, fine fibre, whole mount showing medulla filled with mountant, 400¥; (c) rabbit, cross-sections of light fawn matchings, 200¥. Reproduced from H.M. Appleyard. A Guide the Identification of Animal Fibres by kind permission of BTTG, Wira House, West Park Ring Road, Leeds LS16 6QL.
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Silk, mohair, cashmere and other luxury fibres
quality and quantity of food supplied, are major factors affecting yield. Raising Angora rabbits for their hair is labour-intensive and highly skilled work if the results are to be viable. The fibre is very fine and very smooth. This makes it difficult to spin, with a constant risk of fibre shedding, but the lack of fibre-to-fibre friction is overcome in spinning by the twist imparted and the length of the fibre. Hairs from other breeds, which are shorter, cannot be spun into yarns of adequate levelness and strength. The fibre is usually blended with other fibres such as fine wools, often with a small proportion of nylon. There are two principal types of hair; the ‘French’ and the ‘German’ type. The former contains guard hairs which do not dye, is longer and ‘spikier’ than the German type and can be used to produce a fine brushed appearance. The German type is finer in diameter and produces a softer yarn.
3.8.3 Prices and distribution Both production and prices have shown extraordinary variations, beyond those justified by the three to five year fashion cycle. For example, from 1976 to 1978 prices doubled from US$13/kg to US$28/kg. These prices further increased, obviously as the result of demand exceeding supply, and during the next ten years reached US$45 to 50/kg. In 1988 the situation was reversed, production exceeded demand and the price fell back to US$20/kg. In that year production was estimated at some 9000 tonnes. In 1992 the price increased to US$30/kg. In 2000, with a world production of around 3000 tonnes, and in the first quarter of 2001 the price averaged at US$16/kg,6 which is below French production prices, with the result that French production is in crisis, despite French Angora’s traditional premium of approximately 50 % over world prices.
3.8.4 End-uses Rabbit hair is principally used for knitting, usually blended with other fibres, mainly wool, and usually spun on the woollen system. Its annual consumption is greatly influenced by fashion and fluctates between 5000 and 6000 tonnes.6
3.9
Yak fibre
The yak (Bos (poephagus) grunniens) is a bovine. It is a shaggy, massivelooking animal – the adult weighs about 350 kg. It is depicted in Fig. 3.15. Yaks live on the high slopes of the Himalayas from the snow line down to approximately 1000 m below it and sometimes inhabit land up to 6000 m. There are both wild and domestic yaks.
Cashmere, camelhair and other hair fibres
167
3.15 Yak reproduced from Pier Giuseppe Alvigini, The Fibres Nearest the Sky, Mondadori Editore, Verona, by kind permission of Mr Pier Alvigini at Alvigini S.A.S. 13900 Biella Via Dante, 12 Casella Postale 430, Italy.
Domesticated yaks are beasts of burden and produce meat, milk, leather and fibres for the local population, who may live at altitudes up to 4000 m, and higher in certain cases. Crosses between yaks and Himalayan cattle living below the yaks’ altitudes are bred to operate lower in the mountains but above the possibilities of wheeled transport. Yaks have developed the outer guard hair and fine down of other species living under similar cold conditions.
3.9.1 Production, fibre characteristics and distribution Each yak produces about 100 g of down fibre per year and although no recent figures of total production are available, about 1000 tonnes per year would seem to be a reasonable estimate. China (Qinhai, Sichuan and Gansu provinces) is the major producer of the down hair that is commercialised. The down is harvested by combing or pulling the fibres during the spring moulting period. The calves’ down fibres are 40 mm to 50 mm long and between 15 and 17 mm in diameter, placing them in a similar class to the very fine and soft category of the guanaco, vicuña and musk ox. Table 3.12 gives information about the fibres. The diameter of the adults’ hair is coarser, between 18 mm and 20 mm and their length is from 30 mm to 35 mm, as is shown in Fig. 3.16. The fine hair has no medulla but the coarser guard hair is medullated, sometimes irregularly. Yak hair is white (that, as with all animal fibres is the most valuable because it can be dyed to any shade), fawn, dark grey and dark brown.
Narrow interrupted or continuous
None
None to very dense
None to very dense
Oval to circular
Oval to circular
None or narrow
None
Fairly thick
Thin
Cuticle
None to very dense, even
None to very dense, even
Pigment distribution
Mid-length
Waved crenate, near margins
Tip
Waved crenate, near to close margins
Waved mosaic, smooth near margins
Base
Scale pattern
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Coarse Regular diameter, scale margins protrude slightly
Fine Fairly regular diameter, scale margins slightly prominent
Medulla
Contour
Pigment distribution
Profile
Medulla
Cross-section
Whole mount
Table 3.12 Whole mount, cross-section and scale pattern of yak
3.16 Yak fibres: (a) fine fibre, whole mount, 200¥; (b) coarse fibre, whole mount, 200¥; (c) fine fibre, cast of scale pattern, 400¥; (d) coarse fibre, cast of scale pattern, 400¥; (e) cross-sections, 200¥. Reproduced from H.M. Appleyard. A Guide to the Identification of Animal Fibres by kind permission of BTTG, Wira House, West Park Ring Road, Leeds LS16 6QL.
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Silk, mohair, cashmere and other luxury fibres
When gathered by the farmers, the fibre, which has not yet been dehaired, is packed into sacks and sent to warehouses where it is hand-sorted for colour, and as much as possible of the outer hair removed. Sorters handle about 10 kg per day. The proportions of the colours produced are approximately 10 % white, 20 % fawn, 10 % dark grey (blue) and 60 % brown.
3.9.2 End-uses and consumers Although what must be a substantial part of total yak fibre production is consumed on, or very near, the place of production by farmers or within their local villages, the quantities that are distributed and consumed in this way are not known. That part of production destined to be commercialised is machine spun, made into knitwear and exported to the usual developed countries, mostly through Chinese knitting companies. Some yak hair is exported and becomes available through merchants in the world’s major textile centres.
3.10
Musk ox fibre
Musk ox (Ovibos moschatus) are large animals, weighing between 250 and 400 kg and varying between 1 and 2 m high; they live in the extreme north of Canada and Greenland. See Fig. 3.17. Their full name is the bearded Canadian musk ox and they are members of the Bovidae family, as are cattle and goats. They were hunted almost to extinction and were saved only by being declared a protected species in 1917. Musk ox are wild, but there are some protected herds. Present population is estimated at 160 000.22
3.17 Musk ox. By kind permission of Ms Nancy Bender, The Musk Ox Company, 633 Fish Hatchery Road, Hamilton, Montana 59840 USA.
Wide lattice
None
Some very dense, often in large aggregates dense
Uneven, some large aggregates
Flattened oval
Circular to oval
Concentric
None
Thin
Thin
Cuticle
Some very dense, often most dense near medulla
Bi-lateral
Pigment distribution
Mid-length
Tip
Irregular waved mosaic, smooth; near margins
Irregular waved mosaic, smooth; distant margins
Base
Scale pattern
Source: Guide to the Identification of Animal Fibres, H.M. Appleyard, by kind permission of BTTG, Wira House, West Park Ring Road, Leeds, LS16 6QL.
Coarse Fairly regular diameter, fairly smooth
Fine Fairly regular diameter, fairly smooth
Medulla
Contour
Pigment distribution
Profile
Medulla
Cross-section
Whole mount
Table 3.13 Whole mount, cross-section and scale pattern of musk ox
d 3.18 Musk ox fibres: (a) fine fibre, whole mount, 200¥; (b) coarse fibre, whole mount, 200¥; (c) cross-sections, 200¥; (d) fine fibre, cast of scale pattern, 400¥; (e) coarse fibre, cast of scale pattern, 400¥. Reproduced from H.M. Appleyard. A Guide to the Identification of Animal Fibres by kind permission of BTTG, Wira House, West Park Ring Road, Leeds LS16 6QL.
Cashmere, camelhair and other hair fibres
173
3.10.1 Production, fibre characteristics and distribution Musk ox have the two types of hair that are usual in mammals living in such cold conditions, fine under-hair or down, and coarse outer guard hairs; Table 3.13 gives relevant information. The native name for the down is qiviut, or quiviuk.9,22 During the spring moult the musk ox loses down hair which falls off in large slabs and is collected. Each animal produces around 1.5 kg of down of which perhaps 60 % is recoverable by conventional dehairing techniques. Higharctic employ a process which recovers nearly 100 % of the down.23 The fibres are unmedullated, with an average diameter of 12.5 mm and a range of 17–22 mm. The guard hair diameter is 30 mm or over. Figure 3.18 shows musk ox fibres. This places quiviut amongst the finest hair fibres because it is comparatively smooth with low crimp. Length is 40–70 mm. Scoured and dehaired fibre is light brown to chocolate brown in colour.22 The fibres need to be dehaired before being machine spun and dyed, if required. The dehairing is done manually by the Inuit or by the Forte Cashmere Company, Inc in Rhode Island, USA, which receives the fibres in batches of 500 or 1000 kg from the Ooming Mak Musk Ox Production Corporation in Anchorage, Alaska.7 Alternatively, the dehairing is carried out by Higharctic. The down is rather short to be spun on the worsted system and needs to be blended with another longer fibre such as baby alpaca;16 if it is 100 % qiviut it is usually woollen spun. Annual qiviut production is estimated at approximately 3000 kg16 which is small, even by ‘luxury fibre’ standards and similar to the production of guanaco at around 5000 kg.
3.10.2 End-uses and distribution The development of the musk ox fibre market, small as it is, was due to the desire to encourage the economic development of the isolated communities of the far north. Once dehaired locally or at the Forte Cashmere Company and spun, and apart from a small quantity used for blending with other fibres, the qiviut is sent back to the far north and hand-knitted by Eskimo women, working at home. Most of the knitwear produced is sold to tourists and to a few high-class boutiques.23
References 1 Atlantic Monthly, Oct 99, 80–82. 2 Wool Record, Oct 99, 7. 3 Dalton Lucerne, The Homestead Farm, Bakestonedale Rd, Pott Shrigley, Macclesfield SK 10 5RU. 4 Hunter L, Mohair: A Review of its Properties, Processing and Applications. Jointly published by CSIR, Division of Textile Technology, International Mohair Association, and the Textile Institute, Port Elizabeth, 1993.
174 5 6 7 8 9 10 11 12
13 14 15 16 17 18 19 20 21 22 23 24 25 26
27 28
29 30 31
Silk, mohair, cashmere and other luxury fibres
Centexbel. (Private communication) Seal A, Seal International, Bradford, UK. (Private communication) Cashmere and Camel Manufacturers Association. (Private communication) Cashmere and Camelhair Manufacturer’s Institute web site, www.cashmere.org Petrie O J, FAO Rome, ‘Harvesting of textile animal fibres’, www.fao.org/docrep/v/93884e00htm Dalton Lucerne Ltd. (Private communication) CCMI and Forte Cashmere Inc, Rhode Island, USA. (Private communication) Phan K-H and Wortmann F J, ‘Quality assessment of goat hair for textile use’, Proceedings of the 7th International conference on goats. France, May 2000, Aachen, Deutsches Wollforschungsinstitut. Scotland and China and the cashmere trade. Theresa Purcell TED case study, Rome, The American University, May 1996. Alpaca.com. alpacanet/alpacavitalstatistics.cfm britannica.com/seo/a/alpaca Rainsford F E E, Internacional de Commercio S.A. Arequipa, Peru. ‘Alpaca History’, Alpasocks.50megs/Alpaca History.htm Britannic.com/seo/l/llama ‘Llama Fiber’ llama.org/llama_fiber.htm Rainsford F E B, ‘The re-emergence of vicuña as a commercial fibre,’ World Conference of the Textile Institute, 2000. The Textile Institute, Manchester. United Nations Food and Agriculture Organisation, ‘Production of rabbit skins and hairs for textiles’, Fao.org/docrep/t1690e/t1690/e0a.htm Qiviut home page. www.higharctic.bc.ca Borsted M,
[email protected] (Private communication) Springhall S, Woodward J and Sinclair A, ‘New Zealand cashgora – the fibre and its marketing’, Proc Int Wool Text Res Conf, Christchurch, 11(327), 1990. Anon.,‘Positive view taken of cashgora prospects’, Wool Rec, 149(3546), 37, 1990. Phan K-H, Wortmann F-J, Wortmann G and Arns W, ‘Characterisation of speciality animal fibres’, Proc 1st Int Symp Speciality Animal Fibres, Aachen, DWI 103, 137, 1998. Ryder M L, ‘The production of goat fibres’, Proc 2nd Symp Speciality Animal Fibres, Aachen, DWI 106, 175, 1990. Tucker D J, Hudson A H F, Ozolins G V, Rivett D E and Jones L N, ‘Some Aspects of the Structure and Composition of Speciality Animal Fibres’, Proc 2nd Symp Speciality Animal Fibres, Aachen, DWI 103, 71, 1988. Friedlin R, ‘Cashgora: A natural choice for the 90’s’, Int Text, 716, 18, 1990. Friedlin R and Petit M,‘Cashgora, the first new natural textile fiber of the last 100 years’, Proc 1st Int Symp Speciality Animal Fibres, Aachen, DWI 103 (1), 1988. Albertin J, Souren I and Rouette H-K, ‘Cashgora or Cashmere?’, Textil-Praxis, 1990, 45, 11 and 729.
Bibliography Alvigini P G, The Fibres Nearest the Sky, Verona, A Mondadori Editore, 1979. Appleyard H M, Guide to the Identification of Animal Fibres, Leeds, British Textile Technology Group, 2e, 1978. Watkins P and Buxton A, Luxury Fibres, London, The Economist Intelligence Unit, 1992.
Glossary
Glossary Commonly used silk terms Basin waste Bave Boiling-off Bolting cloth Brin Burn-out
Chiffon Cohesion Cooking
Crêpe
Crêpe-de-Chine Crêpe georgette Crêpe satin Croisure
Denier Dupion Faille Fibroin
A form of silk waste obtained from cocoons which have been only partially reeled because of frequent yarn-breaks. The double strand of fibroin bonded together by sericin. The process designed to remove the sericin from the bave (also called de-gumming). A fine silk fabric used for filtering purposes (e.g. flour). Each of the two silk filaments making up the bave. A technique used to produce a raised design using acid. Burn-out is always carried out on a fabric made of two fibres, often silk/viscose. A light, semi-transparent fabric made from a highly twisted single raw silk yarn in the warp and the weft. The bonding of several raw silk filaments during reeling. The process by which dry cocoons are soaked in hot water prior to reeling, so as to soften (but not remove) the gum or sericin. A yarn obtained from two or more twisted raw silk yarns (2400–3000 turns/metre). By extension, a fabric made from such yarns. Fabric made with a raw silk warp and a crêpe weft. Fabric with a 2S/2Z twisted yarn in both the warp and the weft. A raw silk warp and a crêpe weft, with a satin weave. The crossing of the raw silk yarn over itself during reeling. The croisure ensures the removal of excess water, reduces irregularities in the yarn and improves cohesion. The weight in grams of 9000 metres of raw silk yarn. Silk reeled from double cocoons and introduced in the weaving process to give an irregular slub effect. Ribbed fabric with a cross-wise rib effect. The protein substance composing the silk filament.
175
176
Glossary
Floss silk Gum Habutae Lousiness
Mommé
Noils Organza Organzine
Pongee Reeling Renditta
Schappe
Scroop Shantung
Shot silk
Spinning Taffeta (or tabby) Tussah (or tassah, or tasar)
Waste silk
Weighting
Short fibres removed from the outside of cocoons before reeling. Another name for sericin, which serves to cement the two brins together and protect them. A light fabric made from untwisted or lightly twisted raw silk yarn (also known as habotai or pongee). A defect of raw silk characterised by white specks which resemble lice but are in fact due to the splitting-up of the silk filament into fibrils. A traditional Japanese unit of measurement, equivalent to roughly 4.48 g/m2. Silk fabrics are often referred to as 8 mommé (8 mm), 14 mm, etc. Short fibres resulting from the silk spinning process. Non-degummed silk fabric with a stiff handle. One of the basic twists given to silk yarns, in which two or more single yarns each receive an initial twist of 600–700 tpm before being assembled and twisted in the opposite direction 300–500 tpm. See Habutae. The process of winding the silk yarn from the cocoons. A term used (especially in India) to indicate the quantity of cocoons required to produce 1 kg of raw silk. If it takes 6 kg of cocoons to make 1 kg of raw silk, this is called ‘6 renditta’. Often used as a synonym for all spun silk, ‘schappe’ originally meant waste silk which had undergone a fermentation treatment. The characteristic crisp hand and rustling sound of a silk fabric. Although this type of fabric was originally made from wild silk, the term shantung is now often used to describe a fabric including some dupion yarn, with a characteristic slubby effect in the weft, commonly used in bridal wear. Usually a tabby weave with different colours in the warp and weft, giving a changing colour effect according to the angle of the light. (i) The production of silk filament by the silkworm; (ii) the manufacture of spun silk from short fibres. Plain-woven fabric using dyed yarns. The organzine warp is often weighted, which gives the fabric a stiff, structured hand. Wild silk produced by silkworms of various species, mainly in India and China, which differ from Bombyx mori in that they are either totally wild or semi-domesticated and their food is not mulberry leaves but oak leaves. Collectively, all the short fibres produced before or during reeling, either from unreelable or pierced cocoons or from waste produced during the reeling process. The replacement of the sericin lost during de-gumming (roughly 20–25 % of the weight of the yarn). When this weight-loss is exactly made up for, we speak of ‘par weight-
Glossary
177
ing’ or ‘weight-for-weight’ but sometimes additional weighting is added over par. The traditional weighting agent was stannic acid (tin salts) but for ecological reasons this is now often replaced by ‘chemical grafting’, in which a polymer of methyl methacrylate is ‘grafted’ onto the molecular structure of the silk yarn.
Commonly used mohair terms Adult hair (Adults)
Mohair shorn from the goat, referred to as the adult goat, generally after the fourth shearing (i.e. the fifth and subsequent shearings). Amino acids Any of a group of nitrogenous compounds that form the component molecules of proteins. Amorphous Not having a crystalline structure. Astrakhan (fabric) A curled-pile fabric which imitates the fleece of a stillborn or very young Astrakhan lamb. Bulk The volume occupied by a standardised mass (weight) of randomised clean fibre compressed by a standard force or pressure. Carbonising A chemical process, generally using acid, which degrades the vegetable matter in animal fibres to a brittle (carbon) form so that it can be removed by crushing and dedusting. Character Refers to the waves or crimps (undulations) that appear in the mohair staple or lock (i.e. waviness or crimp). Cortex The inner portion of most animal hair fibres, comprising spindle-shaped cortical cells. Cotted (Cotts, Cotting) Matted or felted fibres in the mohair fleece. Crabbing A process of setting fabric in a smooth flat state, generally using a hot or boiling aqueous medium. Cuticle The protective outer layer that covers the epidermis of the fibre. Cytoplasm The protoplasm of a cell excluding the nucleus. Epidermis The outer protective layer of cells. Felting Matting together (entangling) of fibres during processing or in use. Fly Fibres that fly into the atmosphere during processing. Follicle That section of the skin which produces a fibre. Gare Long hairy-type fibres having a broken (interrupted) medulla and a chalky appearance. Grease The waxes secreted by the sebaceous glands in the skin of the animal. Hauteur The mean length (length biased) of long-staple fibres in roving, sliver or top form. Heterotype Fibres which have a broken (interrupted) medulla. Hygral expansion The irreversible change in dimensions of fabrics containing hygroscopic fibres as a result of changes in regain (moisture content).
178
Glossary
Initial modulus
Kemp Kid hair (Kids)
Lox (or locks) Matrix Medulla
Morphology Noil Regain Resilience Sebaceous Setting (Set)
Staple Staple crimp Staple length Style Sudoriferous Suint/Sweat Switch Tenacity Yolk
The ratio of stress to corresponding strain in fibres (or yarns) below the proportional (Hookean) limit. Related to stiffness. A relatively coarse mohair fibre having a wide medulla (often lattice in type) and a whitish (milky) appearance. Generally the mohair obtained from the first (at six months) and second (at one year) shearing, provided it is no coarser than 30 mm on average. Medium to heavily stained mohair. The intercellular substance of cells. Central portion (canal) of certain animal fibres consisting of a series of air-filled cavities formed by medullar cells which collapse during the growth period. Branch of biology concerned with the form and structure of organisms. Relatively short fibres, as well as neps and small particles of vegetable matter, removed during the combing process. Moisture content expressed as a percentage of the dry weight (mass) of the fibre. The ability of the fibre (or fibrous mass) to recover from distortion (compression, bending or elongation). Glands in the skin which secrete grease (waxes). Conferring stability (i.e. releasing strain) in a fibre, yarn or fabric, either by heat, moisture or chemical treatment or by a combination of these. A well-defined lock (bundle or tuft) of fibres forming a discrete (cohesive) unit in the fleece. The crimp (undulations or wave) frequency of a staple. The length of a staple from tip to base. Generally refers to the twist and spiral formation (i.e. type of ringlets) of the mohair fibres in the staple. Glands in the skin or follicles which secrete sweat (suint). Excretion from the sweat (sudoriferous) glands of the follicles. A tress of false hair or hair piece used to give added length or bulk to a woman’s own hair. Maximum specific stress (i.e. cross-section related strength) developed in a tensile test taken to rupture. The mixture of products secreted by the glands in the skin of the animal.
Appendix 1 International trade rules for raw silk and other products of silk (ratified by the Directing Board, 7 November, 1997 at Bangkok)
Introduction Task setting and conduct of proceedings At the Brighton Congress 1995, the proposal of the Swiss National Delegate, Mr P Zwicky, to set up a sub-committee under the chairmanship of Mr P Giger, President of Section III, aimed at adapting the International Trade Rules for Raw Silk to actual requirements, found unanimous approval. A first review of the existing Rules – dating back to 1978 – showed that the Rules now as before served its purpose still reasonably well with some parts in need of amendment though. By and large it involved a textual up-dating concerning the inclusion of new means of communication as well as some changes of specifications which took into account the changed practices in the trade. Therefore, the task at hand being judged rather one of small adjustments than one of a monumental revision, it was felt practical that the initial study group be a limited one consisting of a few persons with active experience in the trade. The sub-committee’s study group was composed of: Mr P Giger (chairman), Mr B Trudel, Mr G Gamma, Mr H Frei and Mr P Genoud. Notwithstanding the expertise of this group in technical and trading matters, it was felt necessary also to have reviewed the work by other competent professionals before presenting such a paper to our National Delegates. This commission is most grateful to have been able to draw valuable legal, linguistic and practical advice from Mr S Wesley of the law offices of Bignon & Lebray in Lyon and Mr R Currie, Secretary General of ISA also situated in Lyon. The contributions of these gentlemen greatly added to clarity when formulating the current revision of the existing rules. With the approval of the Executive Committee of ISA the study group submitted a first version of the International Trade Rules for Raw Silk in May 1997 to the National Delegates for examination by or on behalf of their members. A number of Delegates responded, and this study group is grateful for the valuable suggestions they made. As for the rest who sent us no response we hope it is right to assume that their silence signals tacit agreement to the suggestions made. We herewith
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present to you the International Trade Rules for Raw Silk (1997) as adopted by the Directing Board of ISA at its Congress meeting on 7 November 1997 at Bangkok.
Scope of application of the International Trade Rules for Raw Silk It is understood that Sellers, intending to sell raw silk or Buyers, intending to buy raw silk under the conditions of these International Trade Rules must advise the other party of the fact. If the Seller and Buyer agree to make their contract subject to these international trade rules, ISA recommends that this be stipulated in writing with the clause ‘contract subject to ISA International Trade Rules for Raw Silk’ or with any similar clause, so as to form an integral part of the contract. In the event of different or additional conditions being stipulated in writing between the contracting parties when the contract is concluded, such conditions shall also form an integral part of the contract. These International Trade Rules are also intended to apply when a difference of opinion or dispute arises between parties to a contract on a matter on which a contract itself is silent or imprecise. The provisions of these International Trade Rules may also apply to transactions between contracting parties in the same country but it is not intended that they shall apply in preference to any national or transnational agreements covering transactions made between governmental or other organisations representing companies trading in these products within the confines of their own national boundaries. It is understood that the term ‘raw silk’ in these rules, unless otherwise specified, refers to all types of mulberry silk threads (including douppion and native silk) reeled from several cocoon filaments – each extruded by the gland of the silkworm Bombyx mori – into a continuous thread. The term ‘raw silk’ in these rules also stands for raw silk which has been doubled, cleaned or otherwise conditioned in preparation of an application thereafter on the loom or, the subsequent transformation in the throwing process. It follows that these rules also cover contracts for the sale of raw silk which has undergone the mentioned treatments. These rules may also be applied for contracts in raw silk filaments produced from types of silk glands other than those of the Bombyx mori silk worm. In such case ISA recommends that the non-mulberry nature of the raw silk be stipulated in the contract with the clause ‘non-mulberry type’, ‘wild silk’ or with any similar clause.
Details of the reviewal work The number and structure of provisions in these rules remain unchanged. They range from ‘Purpose’ to ‘Arbitration’ and number 19 in total. Out of this total, the five provisions concerning Quantities and weights Quality Specified grades, sizes and qualities Open grade and/or size contracts and Packaging and packing contain specifications which are of exclusive character to the trade in raw silk. The remaining set of 14 provisions cover general trade terms and will be newly
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referred to as provisions of general scope under the heading of ‘Supplementary governance’: Purpose Supplementary governance Application Offers, orders and acceptances Confirmation of transactions Price Terms Shipment Force Majeure in the Seller’s Country Force Majeure in the Buyer’s Country Advice of departure Country of origin Variations of charges Arbitration The following points are new and form part of the final version on hand: 1. under ‘Purpose’ In the absence of trade rules for silk products other than raw silk, it is proposed to make applicable the provisions of general scope of these rules – as mentioned above – to other Silk products ranging from thrown silk to boiled-off silk fabrics. In this context we refer to the ‘Rules for Intraeuropean Trade in Raw and Thrown Silks’ dating back to January 1972. Those were drawn up as model rules by another sub-committee of Section III and were intended to be tested during a period of some 10 years. To our knowledge that period has passed without further action and the status of the work remains under test and trial until the sections concerned (III/V) take the initiative to have those rules put in force. Furthermore, it is to be noted that there are no particular trade rules in existence for a wide variety of other silk goods, a situation which is rated by many as a long-felt gap waiting to be filled. Therefore, it was considered meaningful that in the interim those parts of the International Trade Rules for Raw Silk which can be considered as provisions of general scope be endowed with the option of a wider scope of governance. 2. under ‘Application’ An important source of conflict and instability in cross-cultural business relations are differing concepts of what constitutes a binding agreement. Accordingly, not all cultures have the same notion of the binding force of a written contract and of the importance of detailed regulations. This is particularly grave because people tend to think that their own country’s commercial law alone is valid and that the commercial law of any other country is of no consequence. In the interest of reducing misunderstandings and conflicts arising from such differences a stipulation is introduced which does away with the present absence of a clear dividing line between the truly voluntary and the de facto binding nature of a contract. In effect these rules say that a contract once concluded is a binding agreement which is unwound only in the case of Force Majeure and in the special cases mentioned under ‘Terms’, ‘Shipment’ and ‘Specified grades, sizes and qualities’, but any of these events would not itself call into question the original existence of the contract.
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3. under ‘Offers, orders and acceptances’ and others Means of communication: Besides ‘Airmail’ for offers and orders it was considered useful to add for all communication ‘facsimile’ and ‘other means of electronic communication’. The latter point covers the recent type of communication services available in e.g. the internet network such as e-mail. 4. under ‘Force Majeure’ This study group has concluded that the incidence of Force Majeure was most clearly treated and presented in the mentioned ‘Rules for Intraeuropean Trade in Raw and Thrown Silks’ of January 1972. In effect that paper served as basis for some modifications to the old version contained in the present proposal. 5. under ‘Arbitration’ The new proposal reads to change the place of arbitration to the ‘country of the Buyer’. The old version cited the ‘country of destination’ as the place for arbitration. The study group feels that this change is a practical one. 6. under ‘Quality’ The present and old rules suggest that ‘the Seller must furnish the Buyer with official Conditioning House quality tests. Exceptionally, the Buyer and the Seller may agree on another official Conditioning House’. Contrary to this condition of furnishing tests from an official conditioning house, it is, for certain origins, normal practice today to buy and sell raw silk without a certificate produced by an independent testing house but e.g. with a supplier’s quality certificate. Therefore, we suggested that the above stipulation should be amended to read as follows: ‘Exceptionally, the Buyer and the Seller may agree on another official Conditioning House’s quality test or on a quality test issued by either the respective filature or by another mutually approved party.’ 7. under ‘Packaging and packing’ The evolvement of our trade has led to a number of new norms for skeins which can be considered today as standards: the most common circumference of skein is 150 cm and not 140 cm any more. The production of an evenly sized circumference is an important quality requirement. Likewise the weight of 180 g per skein is dominant and in this context we underlined the importance of uniform skein weights. Also we felt it useful to make mention of an old standard requirement: the diamond formation of skein which is known as Grant Reeling. A somewhat more recent requirement is the bundling of the skeins; they should come flat packed in the make-up of slightly twisted flat skeins. Apart from the packaging in skeins we added the packaging on supports with a listing of the necessary type of specifications to be made for each contract. Each one of the national organisations will translate these rules – where need be – into the language of its own country. If there are doubts about the interpretation of these texts by the parties which have decided to follow the rules in their business relations, the French text, only, is legally binding. Section III, Sub-committee for the revision of the International Trade Rules for Raw Silk Chairman Paul Giger
Zurich, November 1997
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International trade rules for raw silk and other products of silk Purpose These rules are agreed upon and adopted by the International Silk Association for the purpose of defining uniform trade practices between Buyers and Sellers of Raw Silk and for the guidance of arbitrators in the settlement of any disputes arising out of contracts made subject to these rules.
Supplementary governance The provisions of general scope of these International Trade Rules for Raw Silk may also apply to international contracts covering transactions in other silk products such as: 1 2 3 4 5 6
Thrown silk Spun silk Tops All types of silk waste Silk fabrics loom-state Silk fabrics boiled-off
Such provisions of general scope are those stated in these rules subject to the exclusion of the specifications concerning ‘Quantities and weights’, ‘quality’, ‘specified grades, sizes and qualities’, ‘open grade and/or size contracts’ and those for ‘Packaging and packing’.
Application Contracting parties recognise that these rules will automatically apply to their contract when the transaction is concluded and accept said rules as an irrevocable binding agreement, unless specifically stipulated to the contrary. These rules will therefore validly regulate the contract the parties have entered into and they automatically accept their application to the interpretation of the contract and for the purpose of resolution of disputes. However, nothing in the following Rules shall be construed as waiving the right in individual transactions to make any special agreement, but the Rules shall govern in cases where no special agreement exists.
Offers, orders and acceptances Airmail, telegrams, telex, facsimiles or other means of electronic communication containing offers or orders should clearly state the time and date until which the same are valid, and it is understood, unless specifically stated to the contrary, that this time shall be that of the country from which the offer or the order is made.
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To eliminate the possibility of misunderstanding, the Seller or the Buyer, upon acceptance of his offer or order, must acknowledge receipt by cable, telex, facsimile or other means of electronic communication.
Confirmation of transactions Upon concluding a transaction by telegram, telex, facsimile or other means of electronic communication, the Seller shall airmail to the Buyer written confirmation, giving full details of quantity, quality, price and terms, delivery dates and all other relevant details. Failure to protest immediately by telegram, telex, facsimile or other means of electronic communication shall imply acceptance of the contract. Should it be found that, owing to a fault of telecommunication, an order is confirmed otherwise than had been intended, the Seller shall be bound to execute his contract only in so far as he can do so without material loss to himself. The Buyer has the right to accept the purchase as it is made but need only take delivery of what he has ordered.
Quantities and weights Total contract quantities shall be expressed in kilograms and in equivalents of the trade unit by specifying the latter’s type and weight (bales of approx. 60 kg, cartons of approx. 30 kg or other suitable unit). The total weight in kilograms tendered shall not vary by more than 5 % (five percent) above or below the contracted weight. Unless otherwise specified, all Raw Silk contracts shall be concluded and delivered on the basis of conditioned weight, which is the absolute dry weight plus 11 %, and Weight Test Certificates made by the Official Conditioning House of the producing market shall be furnished by the Seller to the Buyer and such Weight Test Certificates shall be accepted as final in the absence of irrefutable evidence of error or fraud. In the absence of such an official body in the producer country, the Buyer and the Seller shall specify that the weight certificate emanates from either the reeler (in such case net unconditioned weight) or from an Official Conditioning House in another country or from another mutually approved party.
Quality Grading and classification must be established in accordance with the testing and classification method in force in the producer country or in the country where, according to the contract, the raw silk will have been or will be tested. The Seller must furnish the Buyer with Official Conditioning House quality tests of the producer market. Exceptionally, the Buyer and the Seller may agree on another Official Conditioning House’s quality test or on a quality test issued by either the respective filature or by another mutually accepted laboratory. These Tests must be accepted as final in the absence of irrefutable evidence of error, fraud or existence of hidden defect. Introduction of chemical matter or other adulteration escaping scrutiny at the Conditioning House, calculated to fraudulently increase the weight or quality of the
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silk, shall be regarded as a hidden defect. Arté, i.e. damage caused by insects, is a hidden defect.
Price Prices shall be mutually arranged between Seller and Buyer in any currency convenient to both parties.
Terms Unless otherwise specified, all prices stated in offers or orders are understood to be CFR (Incoterms 1990) with goods travelling at the consignee’s risk. In this case the buyer must take out insurance and pay the premium. Sales calling for Banker’s Credits require the Buyer to furnish a Banker’s Letter of Credit satisfactory to the Seller and in accordance with the conditions of the transaction. Should the Buyer within the term of the performance of a contract default in payment or give the Seller other reasonable cause to consider his credit risk unsatisfactory, the Seller may demand immediate issuance of an irrevocable and confirmed Banker’s Credit for all open transactions, notwithstanding the terms originally agreed upon, and the election by the Seller to make such a demand shall not impair the obligation of the Buyer to take delivery. Should the Buyer unreasonably refuse to comply with such a demand, the Seller may cancel the undelivered portion of his open contracts by notifying the Buyer by cable, telex, facsimile or other means of electronic communication and confirming it in writing by airmail. In such a case the two parties shall be respectively entitled to or responsible for the difference between the contract price and market price of the undelivered portions of the contract or contracts at the time of cancellation.
Shipment Raw Silk contracted as available for prompt shipment requires the Seller to ship within 15 (fifteen) days from the date of contract or by the first available transportation opportunity provided in the contract (ship, plane, train, lorry, van) after the 15 days period. In the event of the contract terms calling for a Banker’s Credit the Seller shall ship within two weeks of receiving the credit, or in default by the first available shipping opportunity after that period. Silk contracted for forward shipment within a specified month shall be shipped before the last day of that month, but there shall be an allowed latitude of 5 (five) days, which can be extended only by mutual consent or in the event of there being no immediate means of transport to the required destination. If the contracted shipment is spread over more than one month it is understood that, unless otherwise specified, the Seller must deliver in as nearly equal monthly portions as is possible, except when fewer than twenty bales have been contracted. The date of the shipping document shall be deemed to be the date of shipment. A delay in shipment beyond the allowance stated above shall give the Buyer the right to cancel the contract or demand an appropriate rebate or set off corresponding to the market difference at time of cancellation.
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Appendix 1 International trade rules for raw silk
Force Majeure in the Seller’s Country Events alleged as a basis for a claim of Force Majeure must be confirmed by an official body or official National Association of the Seller’s country. In all cases of Force Majeure, the Seller is under an obligation to inform the Buyer by the quickest possible means as soon as possible. Events recognised as Force Majeure may be of two categories, the first justifying a delay in performing the contract, the second resulting in cancellation of the contract.
A: First category – involving delay, includes GENERAL CASES: a) Interruption of means of transport, accidents or quarantine. b) General Strikes, officially declared, and which the Seller is unable to prevent, or strikes of the dockers or of seamen. c) Government orders or measures taken by any governmental authority. SPECIAL CASES: covering sales of silk from a specific reeling plant: d) Epidemic in the mill. e) Strikes, necessitating the stoppage of the mill operations, officially declared. f) Other production delays beyond the Seller’s control. In such cases the stipulated date of shipment shall automatically be extended by 30 (thirty) days. When the delay exceeds this period, the Buyer shall have the option of granting a further extension or of cancelling the lot of silk in question without liability to Seller or Buyer.
B: Second category – involving cancellation of contract where performance becomes impossible, includes GENERAL CASES: a)
Events arising from elements such as fire, floods, earthquake, tidal waves, any other cataclysm and the consequences arising from same, leading to loss of goods. b) Shipwreck and other transportation accidents leading to loss of goods. c) Theft during transport. d) War, state of war, revolution, civil insurrection and all political disturbances and the consequences arising from same. SPECIAL CASES: covering sales of Silk of a specific reeling plant: e) f)
Total or partial destruction of a factory by fire, flood or earthquake. Involuntary failure, bankruptcy or liquidation of the producer in the country of origin.
In such cases where it appears to be materially impossible to deliver the goods, the contract or the undelivered portion thereof shall be cancelled without liability to
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187
Seller or Buyer, after refusal by the Buyer to receive similar goods from another filature in the producer country.
Force Majeure in the Buyer’s Country A case of Force Majeure may arise in the event of government regulations delaying or preventing the importation of raw silk into the country of the Buyer. Events alleged as a basis for a claim of Force Majeure must be confirmed by an official body of the Buyer’s country, and the Buyer is under an obligation to inform the Seller by the quickest possible means as soon as possible. In the event of government regulations involving a delay, the stipulated shipment shall be automatically extended by 30 (thirty) days. If the delay exceeds this period, the Seller shall have the option of granting a further extension or of cancelling the lot of silk in question without liability to Seller or Buyer. In the event of government regulations completely preventing the importation of raw silk into the country of the Buyer, the contract or undelivered portion thereof shall be cancelled without liability to Seller or Buyer.
Specified grades, sizes and qualities If, under the heading ‘quality’, the Silk Conditioning House Tests show the silk to be of a grade lower than, or of a size different from the description given in the contract, the Buyer has the option of accepting the same with an appropriate rebate or he may cancel the contract or demand an appropriate replacement. If the replacement too proves to be lower in grade and/or different in size, the Buyer is again entitled to cancel or to ask for an appropriate rebate or replacement. If the contract permits any latitude in grade or size and the Seller tenders silk within said latitude, the Buyer must accept delivery.
Open grade and/or size contracts Contracts calling for delivery of various grades and/or sizes at the Buyer’s or Seller’s option require the Buyer or the Seller to notify the Seller or the Buyer of the grades and sizes to be delivered at least 30 (thirty) days in advance of delivery month.
Advice of departure The Seller is under an obligation to advise the Buyer by telegram, telex, facsimile or other means of electronic communication as soon as possible after departure of the name of the steamer by which silk has been shipped, or of any other relevant information; for instance flight number in the case of air freight, or shipment by road, rail, etc., and to recall relevant contract references.
Country of origin All bales, cartons or other suitable packing units must be marked with the country of origin. Unless otherwise specified, it is understood that silk reeled in a particular country is reeled from cocoons produced in that country.
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Appendix 1 International trade rules for raw silk
Packaging and packing In skeins: unless otherwise specified, skeins should be taken as measuring approximately 150 cm circumference, a tolerance of 1 % (one percent) more or less is allowed. Unless otherwise specified, the skeins should be produced by the method of diamond thread traverse system and weigh a minimum of 180 g. The weight of the skeins should – within reasonable tolerance – be evenly matched. Unless otherwise specified, a skein is to come with a minimum of 4 (four) lacings, be flat packed in the make-up of slightly twisted flat skeins. The packing should be fit to withstand the journey to the country of destination. On supports: Buyer and Seller must agree on all necessary specifications such as: type and makeup (cones or tubes), type of winding (pineapple or other), weight per cone/tube, soaking type and soaking percentage. The packing must ensure that silk on supports is protected from friction and outside pressure during the transport to the country of destination.
Variations of charges Any variations in duties or export taxes imposed by the country of origin after the date of contract are for the Seller’s account.
Arbitration It is hoped that with the aid of these rules amicable solutions may be found to disputes arising in the sale and purchase of raw silk. If agreement cannot be reached, the dispute shall be submitted to arbitration in the country of the Buyer unless another place of arbitration has been stipulated in the contract under dispute. The decision of the arbitrator or arbitrators shall be final and binding upon both Buyer and Seller.
Appendix 2 Spider silk MRS JOYCE DALTON
Spider silk has long fascinated human beings for its elegant evolutionary solution – a unique combination of enormous tensile strength and elasticity with an ultra-lightweight fibre. The fibre is produced within the silk glands of spiders and other insects, and is composed completely of silk proteins which have made an irreversible transition from a soluble silk protein solution inside the spider into an insoluble fibre once it has been extruded and entered into contact with the air. Spiders produce a number of silks with different mechanical properties for use in spinning webs or for forming cocoons. Of these, the ‘dragline’ or ‘frame’ silk has been the object of desire for materials engineers because of the extreme performance of its mechanical properties, particularly its tenacity. Despite its superior mechanical properties, spider silk is not used commercially because of an absolute constraint on supply. Spider farming is simply not practical. Unlike that of silkworms, the spider’s territorial and aggressive nature precludes intensive cultivation. Further, it is not the spider cocoon silk that is desired but certain of the components of the web silk. A remarkable biomaterial has been produced from simple protein building blocks over 400 million years of evolution. Native silk from orb-weaving spiders is extremely tough (10.5 J kg), and strong (1–5 Gpa). An inch-thick rope of this material would be able to stop a jet fighter when landing on an aircraft carrier. [Quote: Randy Lewis, University of Wyoming] In Canada, a company called Nexia Biotechnologies is working on producing real spider silk by transferring the silk-producing gene from the spider into the mammary glands of pygmy goats. The spider silk protein is produced in the goats’ milk, from which it is extracted and extruded into silk yarn much as polyester yarn is extruded. The goats currently produce 5 grams of protein per litre of milk. According to this company’s literature, they currently have three advanced materials: BioSteel“ Industrial Fibres, for: 1 2 3
Military and law enforcement use (ballistic protection). Structural engineering (aerospace and transportation). Advanced packaging materials.
189
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Appendix 2 Spider silk
BioSilxTM Proteins, for: 1 2
Cosmetics (make-up, e.g. mascara and lipstick). Skin care.
Their suppleness and softness make them ideal for these applications. BioSteel“ Extreme Performance fibres, are: 1 2
Strong/flexible with power ten times stronger than that of steel. Versatile for advanced engineering applications.
The fibre is eco-friendly, one of Nature’s engineering wonders, a protein filament produced on a large scale and without pollution. Dalton Lucerne have already fire tested spider silk with the very surprising discovery that it has a high degree of natural fire retardancy. Spider web can also be washed in warm water, which turns it into an incredibly soft, silken ball. Editor’s note Mr Ron Currie, author of the chapter on silk, has informed me of the possibility of genetically modifying the silkworm Bombyx mori to enable it to spin spider silk. Should this idea come to fruition, it would provide an alternative way of producing spider silk industrially.
Appendix 3 Composition of mohair fibres and of amino acids
Physical and chemical composition of mohair fibres Chemically, mohair is very similar to wool but because it is predominantly orthocortex, which is chemically less resistant than the para-cortex,74 it is generally more sensitive to various chemicals than is wool and more attention should therefore be given to the chemicals and conditions used during scouring, dyeing, carbonising and finishing.1,38 Ward et al.75 produced Table A3.1 for the chemical composition of mohair and other fibres. Tucker et al.58,65 reviewed the chemistry of speciality animal fibres, stating that the fine speciality animal fibres, such as mohair, consist mainly of protein, water and internal and external lipids. They comprise long spindle-shaped cortical cells surrounded by a flattened sheath of cuticle cells held together by the Cell Membrane Complex (CMC), referred to as the intercellular region or intercellular cement. It surrounds individual cortical cells76 and is composed of lipids, non-keratinous proteins and resistant membranes.72 Cuticle cells are separated from the underlying cortical cells by the CMC.76 Together with proteins, the cell membrane lipids (i.e. internal lipids) are the main components of the cell membrane complex (CMC),58,77 the latter forming a network throughout the whole fibre, thus contributing to cell cohesion (it surrounds the cuticle and cortical cells and holds them together).78 The cell membrane complex has a dramatic influence on fibre and fabric properties (Leeder79 quoted by Tucker et al.58). Tucker et al.58 have reviewed work done on the composition of internal lipids. Spei and Holzem64 reviewed the characterisation of fibre keratins, including mohair, by X-ray, microscope and thermo-analysis methods and presented the following summary: ‘The three main morphological components of fibres, such as mohair, are the cuticle, cortex and membrane complex, with each consisting of further sub-components.64 The cortex consists of individual cortex cells, which are in turn built up from macrofibrils (+ intermacrofibrillar matrix (cement)), microfibrils, protofibrils and a-helices.’64 The microfibril matrix complex largely determines the mechanical properties of fibre keratins and also contributes towards determining other physical properties. The microfibril matrix complex consists of partly helical, low-sulphur microfibrils embedded in a non-helical sulphur-rich matrix. X-ray small-angle studies on chemically modified, extended fibre keratins have shown that at least two ordered regions exist along the fibre axis, and that the matrix, which was previously regarded as amorphous, must have a certain structure.
191
Constituent Total nitrogen Ammonia (amide) nitrogen Amino nitrogen Sulphur Amino acid Alanine Arginine Aspartic acid Cystine Glutamic acid Glycine Histidine Hydroxylysine Isoleucine Leucine Lysine
Wool (Graham et al.)
Wool (Lindley ^)
1.1 4.5 8.1 3.3
3.80 7.72 3.08
10.6 7.2 13.7 15.6
16.2
3.85 9.15 6.40 11.0 13.1 5.30 0.96
1.10 0.33 3.70
16.82
10.6
11.6
3.4 10.5
3.76
16.9
Grams from 100 g of dry keratin
Wool (this research)*
Table A3.1 Comparative analysis of wool, mohair and feathers
3.07 7.63 2.82
3.71 10.49 6.69 11.30 14.98 5.16 0.90
3.68
1.42
16.62
Wool (Simmonds)
11.6 3.3
4.4 10.4 7.3 13.1 16.0 6.5 0.7 0.2
1.37 (0.33) (3.65)
3.90 8.14 3.07
14.2 4.77 0.90
4.26 8.94 7.32
5.3 7.4 1.00
5.4§ 6.88 5.82 6.8§ 9.02 7.2 0.33
1.09 0.25 2.70
1.21 0.35 3.19
Feather (this research)
16.2
Mohair (this research)
17.02
(17.23)
Wool (Speakman)
´
´´
1
Feather (Graham et al.)
84.1 87.8 89.0 82.5
82.3 79.1
0.69 3.43 7.28 9.04 6.55 2.10 6.38 4.96
93.5 98.5 86.0
62.6 62.6 82.4
98.4
0.7 4.0 7.2 9.5 6.6 1.8 6.1 5.5
84.7 91.0 38.0 69.0
2.00 8.8
2.39 6.12
73.3 78.2 92.0
0.38 4.65 10.0 14 4.8
0.52 3.66 5.64 6.05 5.62
* Average values are given for contract (WC) wools. ^ Calculated from results given. The value for serine plus threonine assumes equal weights of each, with allowance for 0.2 % of hydroxylysine. The highest values are used for comparison. The total nitrogen, amino nitrogen, and sulphur given at the head of this column are those computed from the amino acid and ammonia nitrogen contents. § The alanine and cystine contents reported here for feathers are from weighted averages of analysis of feather fractions. One of the two unidentified substances found by Simmonds is allowed for in computing recovery of total weight and nitrogen. Source: Ward et al.75
Recoveries Total weight Total nitrogen Amino nitrogen Sulphur
5.6 5.7
4.00 5.90
Percentage accounted for
16.7^
6.7 5.7 5.1
3.8 5.3
0.6 4.0 8.1
0.54 3.40 6.38 7.16 6.55
= =
Methionine Phenylalanine Proline Serine Threonine Tryptophan Tyrosine Valine
Appendix 3 Composition of mohair fibres and of amino acids 193
´
=
194
Appendix 3 Composition of mohair fibres and of amino acids
Zahn40,63 reviewed the structure of mohair, stating that the strength and resistance to wear of mohair are considered to be a consequence of the regular cortical layer built up from spindle-shaped cells.40 The cortex of mohair comprises microfibrils which are up to 0.2 mm wide, the macrofibrils consisting of bundles of microfibrils which are in hexagonal packing. The microfibrils or keratin intermediate filaments (KIF) represent about 60 to 70 % of the fibre mass. The sub-bundles of the KIF are 8 keratins of 40 to 70 kilodaltons. Each has a central alpha-helical rod domain of 311–314 amino acids. The fundamental building blocks of the KIF are four-chained coiled-coil units consisting of a pair of two-chain coiled-coil molecules. Eight keratins constitute the KIF in cortical cells of both mohair and merino wool fibres.40 Zahn40,63 summarised the work done to date on mohair chemical structure as follows: 1 2 3 4 5 6 7 8
The resistance to wear of mohair is related to the regular structure of the macrofibrils in the cortex. Eight keratins constitute the Keratin Intermediate Filaments (KIF) in cortical cells, not only of merino wool but also of mohair. Mohair has the highest helix content as found by differential scanning calorimetry (DSC). Lysine residues in the KIF of mohair have an axial periodicity of 39 Å in agreement with our present knowledge of the position of lysine in keratins. X-ray studies on mohair gave early evidence for microfibrillar swelling. The presence of a structural regularity at 198 Å has been identified by X-ray work on mohair. Stretching mohair fibres under specified conditions revealed the phenomenon of bimodal elongation of filaments. By combination of these data, a structural model for wool and mohair is proposed: in engineering terms the ‘fibre/matrix’ composite is provided mainly by the KIF. The 50 % non-helical sections are the main components of the ‘matrix’.
Various other articles (see Hunter2) also deal with topics related to those covered in this discussion on mohair. The cortical cells of keratin fibres, such as mohair, consist of filaments (aligned) of relatively low cystine (sulphur) content and high a-helix content (low-sulphur proteins),80,81 surrounded by a non-filamentous matrix containing two protein types, one cystine-rich (high-sulphur proteins) and the other rich in glycine and tyrosine (high-tyrosine proteins)82 and83 (as quoted by Tucker et al.58). There are important differences in composition between keratin fibres which are mainly caused by differences in the amount and type of constituent high-sulphur proteins,84 which could hold the key to the differences in physical properties of keratins.85 Although the constituent proteins of merino wool and mohair appear to contain some remarkable similarities, the overall chemical, physical and morphological properties of these fibre types differ in many respects. There also appears to be evidence that there are differences between Kid mohair and Adult mohair.43 Broadly speaking, two types of cortical cells generally occur, namely para-cortex and ortho-cortex, which differ somewhat in chemical and physical properties. The cystine (sulphur) content of the para-cortex is about twice that of the ortho-cortex,86 and the latter is less stable than the former.70 Mohair (particularly Kid mohair), is predominantly ortho-cortex, but also contains some para-cortex.
Appendix 3 Composition of mohair fibres and of amino acids
195
Amino acid composition The amino acid composition of Kid mohair was found to be largely similar to that of merino and of Lincoln wool.80 Ward et al.75 found that the amino acid values of wool and mohair did not differ very notably, except possibly in the cases of tyrosine, aspartic acid, serine and threonine. The most interesting apparent chemical differences were in the relatively low sulphur (and therefore cystine) contents and the relatively high values for aspartic acid.75 Various investigations into the high-sulphur proteins of both oxidised and reduced mohair have been conducted.87,88,89,90,91 Amino acid analyses have been carried out on mohair by, for example, Swart and co-workers87,92,93,94,95 and Gillespie.96 Swart et al.87 compared the soluble proteins of oxidised mohair and reduced mohair with those of wool. They found that the amino acid composition of wool and mohair as well as the a-, b- and g-keratose isolated from the two fibre types were very similar, with the high-sulphur proteins revealing marked differences. They also showed that oxidised mohair contained more a- and less bkeratose than wool. The physical properties of mohair and wool g-keratins subfractions were similar, although amino acid analysis revealed interesting differences for the sub-fractions. Chromatographic separation, on DEAE-cellulose, indicated that the high-sulphur protein fraction (SCMKB) of wool contained protein compounds which could not be accounted for in similar fractions of mohair. Swart et al.87 presented Table A3.2. Gillespie and Inglis84 compared the highsulphur proteins (SCMKB) from various a-keratins, including mohair (see Table A3.3). Swart56 showed that the amino acid composition of kemp was different from that of Adult mohair, the former containing more b-keratose but less g-keratose than the latter. Swart et al.97 subsequently compared the proteins of Adult mohair, Kid mohair and kemp fibres, the amino acid composition of the fibres revealing differences. This was further supported by the different proportions of the a-, b- and gkeratoses of the fibres and the amino acid composition of these keratoses. Swart et al.97 gave a table summarising the physical measurements on sub-fractions of gkeratose found in Adult mohair, Kid mohair and kemp and also gave the amino acid composition of the sub-fractions of g-keratose from Adult mohair, Kid mohair and kemp (Table A3.4). The elucidation of the first complete amino acid sequence of a keratin protein was achieved by Haylett and Swart.92 One of the first and most extensive surveys on the high-sulphur proteins (SCMKB) from reduced mohair was carried out by Joubert90,91 who defined 5 major proteins by differences in their molecular weights Table A3.2 Keratose contents in mohair and wool Keratose
Origin
Mohair %
Wool %
a-Keratose b-Keratose g-Keratose
KIF Nonkeratins Matrix (IFAP)
58.1 10.3 30.0
53.4 15.8 30.7
Source: Swart et al.87 quoted in Zahn.40
196
Appendix 3 Composition of mohair fibres and of amino acids
Table A3.3 The amino acid composition of high-sulphur proteins from wool and mohair Amino acid
Lincoln
Merino
Romney Marsh
Southdown
Soay
Dorset Horn
Mohair
Lysine Histidine Arginine SCMC Aspartic acid Threonine Serine Glutamine Proline Glycine Alanine Valine Isoleucine Leucine Tyrosine Phenylalanine
1.27 2.60 18.1 14.4 2.22 7.59 9.00 5.27 8.82 4.41 2.25 4.54 2.27 2.81 1.81 1.36
0.95 1.83 18.3 14.6 2.29 7.90 9.80 6.50 9.60 5.30 2.26 4.35 2.75 2.98 1.64 1.45
0.67 1.61 15.6 15.7 2.42 7.12 7.80 5.51 10.2 4.30 2.15 4.30 2.28 3.09 0.81 1.61
0.68 1.53 16.4 16.6 2.05 7.68 8.70 5.63 9.72 4.44 2.05 4.09 2.22 2.73 1.19 1.36
0.83 2.00 14.0 16.7 1.41 7.50 8.75 5.50 9.33 4.08 1.83 4.00 1.91 2.08 1.08 0.91
0.75 1.68 19.8 17.7 2.05 7.55 8.76 5.50 10.4 4.38 2.05 4.29 2.14 2.80 1.58 1.40
0.62 1.43 16.7 14.8 2.01 7.38 8.65 5.82 9.55 4.78 2.35 4.03 2.31 2.84 1.01 1.60
Results expressed as amino acid nitrogen/100 g total nitrogen. These proteins were hydrolysed under reflux and the SCMC content reported was obtained from the sum of half cystine and residual SCMC. Source: Gillespie84.
(approximately 9900, 12 200, 15 500, 19 000 and 22 500), electrophoretic mobilities and amino-acid compositions. Swart et al.98 presented amino acid sequence data on the high-sulphur proteins from the 16 000 dalton groups of mohair and wool, a fiveamino acid-residue repeating unit in the 16 000 dalton group previously being demonstrated by Joubert and Swart (quoted by Swart et al.98). (References are to be found at the end of Chapter 2.)
Source: Swart et al.97
98.09
11.98
Serine
TOTAL
8.54
Proline
2.94
0.63
Phenylalanine
Valine
0.45
Lysine
1.08
1.24
Leucine
Tyrosine
2.72
Isoleucine
8.42
0.73
Histidine
Threonine
7.91
5.02
Glycine
Cysteic acid
Glutamic acid
0.80
18.39
Aspartic acid
10.45
15.57
Arginine
1.82
Adult mohair
Ammonia
Alanine
Amino acid
98.53
3.11
1.13
8.26
11.26
8.78
0.74
0.44
1.36
3.08
0.56
5.43
8.16
18.66
0.56
14.78
10.16
2.06
Kid mohair
g1-keratose
97.60
2.90
1.11
8.82
12.07
8.43
0.83
0.22
1.31
3.18
0.37
5.71
8.50
17.74
0.62
14.62
9.08
2.03
Kemp
99.07
4.17
0.87
8.01
9.99
10.07
1.06
0.56
2.49
2.40
1.35
3.89
6.29
16.50
1.52
19.35
8.24
2.31
Adult mohair
99.15
4.19
0.64
7.45
9.81
9.95
0.89
0.73
2.50
2.55
1.21
4.15
6.38
17.24
1.40
18.47
9.14
2.45
Kid mohair
g2-keratose
99.30
3.95
0.77
8.23
10.25
10.21
1.15
0.64
2.75
2.47
1.48
4.01
6.39
15.90
1.72
17.95
9.11
2.32
Kemp
98.60
4.91
0.62
7.93
7.50
10.05
1.40
0.35
2.14
1.48
0.54
3.32
5.24
15.18
1.53
27.62
6.84
1.95
Adult mohair
99.03
4.19
0.65
7.90
7.94
9.71
1.53
0.32
2.17
1.45
0.58
3.36
5.27
15.03
1.56
27.60
7.01
2.04
Kid mohair
g3-keratose
97.55
4.92
0.58
7.78
7.08
10.01
1.60
0.42
2.17
1.49
0.58
3.44
5.14
15.28
1.62
26.39
7.05
2.00
Kemp
98.41
4.83
0.96
7.62
9.13
9.93
2.17
1.14
4.06
2.36
3.17
4.36
4.15
11.73
3.97
18.80
7.23
2.75
Adult mohair
100.08
5.01
1.08
7.85
9.17
9.92
2.47
1.34
4.57
2.43
4.22
4.41
4.39
11.40
4.73
16.68
7.49
2.92
Kid mohair
g4-keratose
Table A3.4 Amino acid composition of subfractions of g-keratose from Adult mohair, Kid mohair and kemp
98.55
4.61
1.01
7.69
8.22
10.13
2.70
1.49
5.17
2.78
4.23
4.54
3.56
11.19
5.33
15.47
7.39
3.04
Kemp
Appendix 3 Composition of mohair fibres and of amino acids 197
Appendix 4 Mohair yarn spinning and properties
Mohair yarn spinning The most detailed processing studies on mohair were undertaken at the South African Wool Textile Research Institute (SAWTRI) during the 1980s, using the Continental Worsted System, with some lots also being processed on the Noble comb. The studies were aimed at elucidating, amongst other things, the effects of fibre diameter and length on processing behaviour and yarn and fabric properties. In one of the first studies, Turpie and Hunter246 found that spinning potential was mainly affected by fibre diameter, deteriorating with an increase in fibre diameter. In a later study Strydom247 found that the Noble comb removed 2 to 3 % more noil than the French comb (Fig. A4.1), producing tops 4 to 6 mm longer with a lower CV of length. Finer mohair suffered more fibre breakage during processing and as a result exhibited poorer conversion ratios (Fig. A4.2). Nevertheless, they tended to spin better than the coarser qualities, even for the same number of fibres in the yarn crosssection (Fig. A4.3). Mean fibre length, mean fibre diameter and number of fibres in the yarn cross-section were found to explain some 85 % of the observed variation in spinning potential, with the contribution of other variables, such as CV of length and diameter, being non-significant in this particular case. Goen248 reported on the processing of cut mohair top (38 mm length), in various blends with cotton, on a short-staple (cotton) system, blending taking place in the opening room. Although the lower levels of mohair were processed without much difficulty it became increasingly problematic to process the blends as the mohair content increased; it was very difficult to process the 40/60 mohair/cotton blend, more roving twist also being required.248 This caused snarling and the roving had to be steamed. Spinning also became increasingly demanding as the level of mohair increased, yarns ranging from 50 to 75 tex being spun. Strydom249 compared the processing behaviour (Continental System) of Summer and Winter Cape Mohair. He found that once differences in mean staple length and mean fibre diameter, associated with season, had been allowed for (Fig. A4.4 and A4.5), no residual effect of season could be found in any of the relationships governing scoured yields, card wastes, comb noil, top and noil yields, mean fibre diameter in the top, top Hauteur or conversion ratio.249 Season therefore only affected processing performance in so far as it affected the measurable fibre properties, such as staple length and mean fibre diameter. In a follow-up study, Strydom250 compared the processing behaviour of blends of mohair types differing in length.
198
Appendix 4 Mohair yarn spinning and properties 10
199
Long grades (Noble combed) Medium grades Long grades
Noil (% on scoured)
8
(Schlumberger combed)
Short grades
6
4
2
20
25
30 35 Mean fibre diameter (mm)
40
45
Conversion ratio (staple length: Almeter mean fibre length)
A4.1 The effect of mean fibre diameter of the raw hair on percentage noil.247
1.5 Long grades Medium grades
1.4
Short grades
1.3
1.2
1.1
25
30
35
40
45
Mean fibre diameter (mm)
A4.2 The effect of mean fibre diameter on the conversion ratio (Schlumberger combing).247
200
Appendix 4 Mohair yarn spinning and properties
12 000
11 000
Mean fibre length = 105 mm Mean fibre length = 85 mm
9000
8000
7000
6000
5000 30
35 Mean fibre diameter (mm)
40
45
A4.3 Regression curves illustrating the effect of mean fibre diameter on MSS (no. of fibres/cross-section = 40).247
5
Winter hair
4
Summer hair
3 Noil (%)
MSS (rev/min)
10 000
2
1
0
25
30 35 40 Mean fibre diameter (mm)
45
A4.4 The relationship between mean fibre diameter in the grease and percentage noil.249
Appendix 4 Mohair yarn spinning and properties
201
110
Almeter Hauteur (mm)
100
90
80
Winter hair
70
Summer hair 60
90
100 110 120 130 Average staple length (mm)
140
A4.5 The relationship between average staple length in the grease and Almeter Hauteur mean fibre length in the top.249
In a final report on the various studies on the processing of mohair on the continental system, Strydom and Gee251 concluded as follows. Wave frequency (i.e. waviness or crimp) decreased with age, it being negatively correlated with fibre diameter and slightly positively correlated with grease content. The scouring yields observed varied between 78 and 91 %, while card losses varied from 3 to 12 %. Table A4.1 summarises their results. The fibre diameter means and CVs of the top were found to be closely related to those of the unprocessed hair. The top tended to be coarser than the raw hair, from about 0.5 mm coarser at the fine end of the scale (i.e. Kid hair of about 25 mm) to about 1.3 mm coarser at the coarser end of the scale (Adult hair of about 45 mm). (Keller and colleagues at the USDA, quoted by Strydom and Gee,251 found similar differences for Kid hair but only about half this difference for Adult hair.251 Staple length on its own did not appear to be a very good predictor of Hauteur, but by including data on diameter (D), diameter variability (CVd) and wave frequency (WV), some 83 % of the observed variation in hauteur could be explained. Drycombed top and noil yields varied from 73 to 89 %, depending largely upon mohair base.251 There were no systematic differences between the yields estimated from core test data and the actual yields obtained. Diameter played a very important role in determining noil, the latter decreasing almost linearly with an increase in mean fibre diameter; part of this could be due to the correlation between staple length and mean fibre diameter. Their results suggested that mohair, either more variable in length or diameter or both, tended to yield lower top and noil values. The small contribution of a term involving staple length and wave frequency (SL ¥ WV) sug-
CVWV
CV of wave frequency (%)
MB
WV
Wave frequency (cm-1)
VMB
–
CV of fibre length (%)
VM base (%)
–
Mean single fibre length (mm)
Mohair base (%)
CVSL
CV of staple length (%)
GC
SL
Mean staple length (mm)
SC
CVd
CV of diameter (%)
Suint content (%)
D
Mean fibre diameter (mm)
Grease content (%)
Symbol used in text
Independent variable (Greasy mohair data)
0.30
70.9
2.7
4.9
21.0
0.52
37.0
0.1
64.3
2.2
3.3
10.0
0.45
29.0
78
10.0
15.0 106
78
21.0
26.0 107
23.1
Min
27.6
Mean
Kids
0.7
75.1
4.0
8.0
30.0
0.66
44.5
133
22.0
127
33.0
31.6
Max
0.20
70.0
2.9
4.9
21.3
0.47
32.6
115
15.5
110
22.7
32.2
Mean
0.04
65.7
2.4
4.0
10.0
0.42
26.2
95
10.0
84
20.0
29.1
Min
Young goats
Table A4.1 Means and ranges of raw hair characteristics and processing data
0.4
74.1
4.2
5.6
35.0
0.53
36.3
147
27.0
137
26.0
35.3
Max
0.3
73.1
2.5
4.1
24.4
0.39
25.9
110
15.0
111
25.9
38.5
Mean
Adults
0.1
66.5
1.8
2.9
10.0
0.28
28.5
88
10.0
91
21.0
33.0
Min
1.5
77.3
3.2
5.5
42.0
0.46
42.4
129
22.0
126
29.0
44.5
Max
35.6 3.6
CV of single fibre length
Short fibre (% < 25 mm)
Source: Strydom and Gee251
150
99
Long fibre (L @ 5 %)
137
6.4
Short fibre (% < 25 mm)
Single fibre length (mm)
46.2
CV of Hauteur (%)
Long fibre (L @ 5 %)
25.7
Mean fibre diameter (mm) 84
28.5
Top and noil yield (%)
Hauteur (mm)
81.6
Comb noil (%)
CV of diameter (%)
4.3 3.5
Card rejects (%)
84.0
Scoured yield (%)
Dependent variable (Processing factor)
133
1.2
22.0
81
112
1.3
35.5
60
19.0
24.0
72.8
1.2
7.8
77.7
167
7.3
43.0
122
165
23.6
66.3
104
33.0
33.8
89.2
6.3
8.0
91.0
155
3.3
35.3
103
143
6.4
44.9
91
22.5
32.8
80.5
1.8
4.0
82.5
122
1.1
30.0
84
112
0.6
29.8
76
20.0
29.3
78.1
1.1
2.9
79.4
189
5.9
49.0
118
169
17.1
55.6
109
25.0
36.2
85.9
2.5
5.9
86.9
152
3.6
35.3
101
141
3.8
39.4
93
25.4
38.9
83.0
1.3
5.2
86.1
131
1.1
28.0
79
114
0.3
34.2
71
22.0
31.5
76.4
0.6
3.5
80.1
175
7.3
42.0
114
158
12.8
48.0
107
28.0
45.6
87.9
2.0
12.5
90.6
204
Appendix 4 Mohair yarn spinning and properties
Table A4.2 Regression analysis: spinning performance as measured by MSS technique Basis of analysis
r2
Regression equation
No of fibres in yarn cross-section (n)
0.642
-3.0 D2 + 0.57 (H ¥ n) + 1.3 (H ¥ CVH) + 1.5 CVd2 + 2546
Yarn linear density (tex)
0.658
-5.2 D2 + 0.63 (H ¥ tex) + 1.1 (H ¥ CVH) - 0.2 (tex)2 + 6481
Source: Strydom and Gee251
gested that hair either longer or more curly, or both, tended to yield slightly better top and noil values. Strydom and Gee251 found that wave frequency affected the relationship between Almeter and single fibre length results, also confirming that coarser fibres had poorer spinning performance than finer fibres, even when the number of fibres in the yarn cross-section was constant. Table A4.2 summarises the results of their statistical analyses. In both equations a term (H ¥ CVH) appears, which suggested that hair either longer, or more variable in length, or both had better spinning performance. The primary determining factors for MSS, however, remained the number of fibres in the yarn cross-section (n) and mean fibre length (H), with the effect of CVH being of secondary importance in terms of its magnitude.251 In parallel studies252 on the Noble and rectilinear (i.e. French or Continental) combs it was found that, as expected, more noil was produced on the Noble comb than on the rectilinear comb (Fig. A4.1). The noil ranged from as little as 1 to about 5 % during rectilinear combing and from about 4 to 8 % during Noble combing, the amount of noil being dependent upon the diameter of the hair, but not on the length. The increase in noil with decreasing fibre diameter was probably due to more breakage being suffered by the finer fibres during processing. Conversion ratios from the staple to the top ranged from about 1.1 : 1 to 1.4 : 1.252 Hunter and Dorfling253 investigated the effect of Angora goat age on mohair processing performance on the Continental (French) System. They showed that, provided corrections are introduced for differences in the measurable fibre properties, notably diameter and length, goat age has no effect on processing performance and top properties, such as percentage noil and Hauteur (Fig. A4.6 and A4.7). What this essentially means is that provided the fibre characteristics, such as diameter and length, are constant, the age of the goat has no additional effect on mechanical processing performance up to and including spinning performance. In another study254 it was found that mohair of better Style and Character performed better during processing and also showed better textile performance criteria as demonstrated in Fig. A4.8. Minikhiem et al.256 found differences in subjectively assessed style and character to be reflected in top characteristics, such as kemp, diameter and medulla content. Turpie257 has summarised the work done at SAWTRI on the effects of mohair fibre properties, diameter in particular, on processing performance, including spinning. Smith258 discussed some of the processing requirements of the various speciality fibres.
Appendix 4 Mohair yarn spinning and properties
205
7 Kid
6
Young Goat Adult
Actual
5 4 3 2 1 0
0
1
2
3
4
5
6
7
Predicted (n=54) Noil(%) = –0.7684 D + 0.02548 L + 0.008257 D2 + 0.002560 Vd2 + 14.15
A4.6 Percentage noil.255
Actual
120 110
Kid
100
Young Goat Adult
90 80 70 60 50 50
60
70
80
90
100
110
120
Predicted (n=54) Hauteur = –1.239 Vd – 0.02385 D2 + 0.02067 L.D + 71.31, %Fit = 81.5
A4.7 Hauteur (mm).255
Repco-wrapped core spun yarns Various researchers at SAWTRI carried out considerable work on the spinning of mohair yarns,261,262 including slub yarns,263 on the Repco Self-twist spinner, without264 and with nylon filaments.265 It was concluded that the best results were obtained when two multi-filament yarns (usually 17 or 22 dtex nylon) were introduced, the
206
Appendix 4 Mohair yarn spinning and properties Hauteur
CV of Hauteur (Vh)
105 95
CV (%)
Hauteur (mm)
115
85 75 65
Good
Average
Poor
65 60 55 50 45 40 35 30 25 20
Good
Style and Character
Conversion ratio (r) 2.3
32
2.1
26
1.9 20
Ratio
Short fibre content (%)
Short fibre content (Sh. Fib%) (<40mm)
14
1.7 1.5
8
1.3
2 Good
1.1
Average Poor Style and Character
Good
Yarn extension*
Average Poor Style and Character Yarn tenacity*
18 16 14 12 10 8 6 4 2
7.0 Tenacity (cN/Tex)
Extension (%)
Average Poor Style and Character
Good
Average Poor Style and Character
6.6 6.2 5.8 5.4 5.0 4.6 4.2
Good
Average Poor Style and Character
* “calculated” yarn properties
A4.8 Box plots illustrating the effect of mohair style and character on certain textile performance criteria.254
one to act as a core and the other as wrapper. Yarns so spun (and generally uptwisted after spinning – STT) were designated as Repco-Wrapped Core-Spun (RWCS) yarns. Two strands of mohair and one nylon filament core were drafted and self-twisted with a filament binder yarn to form an RWCS yarn265 (see Fig. A4.9). Different variations were developed. The yarns were converted into lightweight fabrics, generally with highly acceptable properties.
DREF friction spinning Robinson et al.266 used the novel feature of the DREF II open-end friction spinning machine that enables the radial positions of the fibres in the yarn cross-section to
Appendix 4 Mohair yarn spinning and properties Self twist rollers
Feed rollers
50 mm
Take-up package
Drafting zone 48 mm 28.2 mm
Roving
Ø25mm
207
Ø23 mm
Filaments
35 mm Guide eyelets Staple fibres Wrapping filament Core filament
Cross-section of yarn
Wrapping filament Staple fibres Core filament
A4.9 RWCS system.157
be predetermined to show how a speciality fibre, such as camelhair or mohair (e.g. noils), can be made to predominate on the yarn surface whilst a cheaper fibre makes up the body of the yarn. In this manner the yarn, and subsequent fabric, has the aesthetic qualities of the speciality fibre in spite of the fact that the latter only makes up a small proportion of the whole.
Worsted yarn properties The most comprehensive studies on the relationship between mohair fibre and yarn properties were carried out by Hunter and co-workers.267,268,269 In a wide ranging study, involving the processing of some 50 mohair lots on the Continental worsted system followed by ring spinning, Hunter et al.269 investigated the effect of fibre properties, notably diameter and length, on yarn and fabric (knitted and woven) properties. They derived multiple regression equations by means of which the yarn and fabric properties could be predicted from fibre diameter, fibre length and yarn linear density and twist. Within the ranges covered, the effect of fibre diameter on yarn properties was far greater than that of fibre length, while the effects of variability (CV) of fibre diameter and fibre length and short fibre content were relatively small. Virtually all the yarn properties deteriorated with an increase in mean fibre diameter (or with a decrease in the number of fibres in the yarn cross-section), while an increase in mean fibre length generally had a beneficial effect.269 Figure A4.10 illustrates some of the main trends. Hunter and Kruger270 investigated the effect of different levels of paraffin wax on the friction of mohair/wool yarns of different blends. They found that this property
208
Appendix 4 Mohair yarn spinning and properties Tenacity (Regression curves) (75 tex Z350)
Extension (Regression curves) (75 tex Z350) 30
Fibre length (mm) 120
10 5
Extension(%)
Tenacity(cN/tex)
15
100 2
20
100
15
80 25
Fibre length (mm) 120
25
30 35 40 45 Mean fibre diameter (µm)
80 30 35 40 45 Mean fibre diameter (µm)
25
Irregularity
Irregularity (Regression curves) (75 tex Z350)
Irregularity (CV%)
25
25
20
20 15
15 25
30 35 40 45 Mean fibre diameter (µm)
25
Kids Young Goats Adults
500
0 20
60 100 Average number of fibres
140
Hairiness (Hairs/m)
1000
50 75 100 125 150 Average number of fibres
Hairiness (75 tex Z350)
Thick places Thick places per 1000 m
Kids Young Goats Adults
Irregularity (CV%)
Fibre length(mm) 80 100 120
30
Fibre length(mm) 80
180 170 160 150 140
100
130 120 110
120 25
30 35 40 45 Mean fibre diameter (µm)
A4.10 The effect of mohair fibre properties on yarn properties.269
increased with increasing mohair content. The phenomenon was ascribed to the extractable matter on the mohair rather than the mohair fibre itself, since solvent extraction or scouring of the yarns prior to waxing eliminated the effect. An important property of textiles, and also therefore of mohair, is its low bending stiffness (flexural rigidity) which makes it suitable for many end-uses, in particular apparel. Understanding the role of the many factors involved in determining flexural rigidity, or bending stiffness, is essential for a better understanding of the broader issue of fabric drape and handle which play such an important role in deter-
Appendix 4 Mohair yarn spinning and properties
209
mining the suitability of a fabric for a particular end-use. It is generally accepted that fibre stiffness plays a dominant role in yarn and fabric stiffness and handle (softness), with fibre stiffness largely a function of fibre diameter, increasing with the fourth power of diameter. Yarn flexural rigidity is important because of its large effect on the bending properties and behaviour of a fabric. Yarn stiffness affects the drape coefficient and, because it is related to fabric flexural rigidity, it also affects the handle of a fabric, handle being closely related to fabric flexural rigidity. It is also of some importance during fabric forming processes (e.g. knitting). (References are to be found at the end of Chapter 2.)
Appendix 5 Mohair fibre and fabric properties
The relationship between fibre properties and the physical properties of fabrics In a comprehensive study, Hunter et al.269 investigated the effects of mohair fibre properties, particularly diameter, length and yarn twist, on the physical properties of plain and twill weave mohair and mohair/wool fabrics. Their conclusions are detailed in the following paragraph. Fibre length generally had little effect on the fabric physical properties, whereas fibre diameter in most cases had an important effect. Drape coefficient, stiffness, abrasion resistance and hygral expansion increased with an increase in fibre diameter, while wrinkle recovery (IWS Thermobench and AKU methods), shrinkage (felting and relaxation), strength and extension decreased with an increase in mean fibre diameter.269 Fibre length and yarn twist, within the ranges covered, generally had little effect of any practical consequence. It also emerged that once differences in mean fibre diameter were corrected for there was little difference between the fabrics containing Kid, Young Goats and Adult mohair. Figure A5.1 illustrates some of the main trends. Galuszynski and Robinson271 investigated the making-up of mohair/wool blend fabrics, recommending the chain-stitch for reducing seam pucker due to the sewing thread.
Fabric objective measurement Those fabric properties important in the making-up (tailorability) and in the appearance of the garment after making-up as well as those playing a role in fabric handle are increasingly being measured. Two systems of fabric objective measurement, namely Kawabata (KES-F) and FAST, have reached the market. Carnaby et al.272 and Kawabata et al.273 reported on the use of objectively measured properties (Kawabata system) of summer (tropical) suitings, including mohair/wool blend weft and 22 mm merino wool warp, to design a suitable fabric containing New Zealand wool. (See also Appendix 4 on the relationship between fibre properties and the physical properties of fabrics.) Fujiwara274 described the design of a mohair blended fabric, with emphasis on the control of fabric handle and quality by objective measurement. He also showed275
210
Appendix 5 Mohair fibre and fabric properties
211
Drape (plain weave)
Drape coefficient (%)
70
–Kids –Young Goats –Adults
65 60 55
25
30 35 40 Fibre diameter (mm)
40 30
Weft tear strength (plain weave)
–Kids –Young Goats –Adults
Tear strength (N)
Flexural rigidity (mN.mm)
Weft flexural rigidity (plain weave)
20 10 25
40 Fibre length (mm)
35
120
30
100
25
80
25
30 35 40 Fibre diameter (mm)
AKU wrinkle severity (plain weave)
80 70
Aged
60
–Kids –Young Goats –Adults
50
Deaged
40 26
30 34 38 Fibre diameter (mm)
42
Wrinkle severity (H¥T)
Crease recovery (%)
IWS crease recovery (plain weave)
30 35 40 Fibre diameter (mm)
.15
–Kids –Young Goats –Adults
Deaged
.10
.05 Aged
0 25
30 35 40 Fibre diameter (mm)
45
A5.1 The effect of fibre diameter on certain woven fabric properties.
how a high quality (good tailorability) mohair/wool fabric could be designed and characterised by objectively measured fabric properties as measured on the Kawabata (KES-F) system. He showed how different parameters, measured by means of the Kawabata system, could be used to distinguish between ‘good’ and ‘bad’ mohair fabrics. For example, the ‘good’ fabrics had shearing (G) values lying between 0.4 and 0.6 while the ‘bad’ fabrics generally had values greater than 0.6. The fabric objective (Kawabata system)-measured properties of a mohair/wool tropical suiting fabric were given,276,277 and so, too, the related yarn properties.277
212
Appendix 5 Mohair fibre and fabric properties
Niwa et al.278 reported on the important handle, suit appearance and other objectively measured characteristics of a high quality mohair/wool tropical suiting fabric, using the Kawabata system of fabric objective measurement. Properties of particular importance included high SHARI (a cool feeling coming from a pleasant rough surface touch), and moderately strong KOSHI (springy stiffness) and/or HARI (spread/anti-cling), the latter being important for producing an air space between the fabric and the skin of the wearer. The TAV (Total Appearance Value) derived from the Kawabata system of fabric objective measurement provided a means of predicting suit making-up performance and appearance, with a value of 5 being excellent and 1 poor.278 Smuts et al.279 have reviewed the work published on the objective measurement of fabric properties, principally by the Kawabata KES-F and the FAST system, including a limited amount of work done on wool/mohair tropical suiting fabrics which had the desired crisp (SHARI) handle. (References may be found at the end of Chapter 2.)
Appendix 6 Mohair dyeing and finishing
Swanepoel283 investigated the dyeing behaviour (rates of dyeing and dye appearance) of wool and mohair, with fibres of both ranging in diameter from 21 to 30 mm. Difference in depth of shade and the rate of dyeing of wool and mohair differed from one dyestuff to another, although the trends were similar for all the dyestuffs. The rate of dyeing of mohair exceeded that of wool of the same diameter, with finer fibres dyeing more rapidly than coarser fibres. The depth of shade of the mohair was greater than that of the wool of the same diameter and containing the same concentration of dyestuff, this being ascribed to the differences in the surface structures of the two fibre types (i.e. the more lustrous nature of the mohair fibre surface).283 For both wool and mohair, the depth of shade of fibres containing the same concentration of dyestuff increased with increasing average fibre diameter. According to Veldsman,284 mohair dyes more rapidly than wool of similar fibre diameter, because of its greater proportion of ortho-cortex, and also appears darker for the same dye uptake, because of its higher lustre. Roberts and Gee285 compared the dyeing behaviour of mohair with that of Corriedale wool of similar diameter. The rate of dyeing of the mohair was found to be greater than that of the Corriedale wool, this conclusion being in line with that of Swanepoel.283 In addition, the equilibrium exhaustion was found to be higher in the case of the mohair. When mohair and the Corriedale wool were dyed to the same nominal depth of shade, differences in apparent depth of shade were very small when assessed both visually and by an instrumental technique. It was speculated that the frequently claimed greater depth of shade obtained on mohair relative to wool was caused by the greater lustre of mohair relative to that, for example, of merino wool and that, when this lustre difference was absent, the apparent strength difference falls away. According to work done by Gandhi286 (quoted by Kidd287) and Onions32 mohair is set more readily than wool, Onions32 stating that the relative ease with which mohair sets accounts for its use in curled pile rugs and simulated Astrakhan fabrics. Grenner and Blankenburg288 investigated the chemical setting, and associated damage, of crinkled mohair and wool yarns and found that a good degree of set could be obtained by boiling for one hour in a pH range of 4 to 6. This was, however, associated with relatively high fibre damage in the case of the mohair. Reducing the setting time to 30 minutes led to an improvement in setting with less fibre damage. Setting and dyeing could be combined into one process.289
213
Appendix 7 Mohair product list
Accessories (hats, gloves, handbags, etc) Airgun darts Airline blankets Ankle socks (girls’) Artificial hair Astrakhan Athletic socks (hosiery) Auto-textiles (floor coverings, carpets, boot liners, hoods, door trims, seats, upholstery, panel shelf) Automobile seat covers Bath mats Bath sets Bed covers Bedspreads Beltings and press cloths Blankets Blazers Blousons Bobby socks Boot linings (automobile) Braid Brilliantine Bunting (flag cloth) Candlewick (bedspreads and dressing gowns) Capes Car coats Cardigans Carpet tiles Carpets, rugs and mats (Axminster, Wilton, tufted, needle-punched, hand-knotted, knitted) Casual wear Ceremonial robes Chenilles (carpets, socks, etc)
214
Appendix 7 Mohair product list
215
Cloaks Coats Coffin linings Cords and tassels Crepon goods Curtains (damask, brocades, satins or velvet) Cushion covers Decorative trimmings (e.g. for coats, hats, shoes) Dinner jackets Dolls’ wigs Domestic textiles Drapes/draperies (automobiles, aeroplanes, furnishings, trains, buses, domestic, office and industrial) Dress suits Dresser covers Dressing gowns Duvets Eiderdowns Evening gowns Evening wear Fabric art Fabric panels Fabric sculptures Fake furs Fancy yarns Fibre art Fire blankets Flags Fleecewear Floor carpeting (aircraft, automobiles and buildings) Foot muffs Foot warmers Fringes Fur (imitation) Furnishings Gilets Gloves Golf club head covers Golf shirts Gowns Half-hose Hand-crocheted articles (shawls, stoles, etc) Hand-knitting yarn Hand-knotted carpets
216
Appendix 7 Mohair product list
Handwear Home furnishings Horse blankets House slippers (felt) Household textiles Imitation furs Infants’ blankets Ink-transfer pads Interior panels Interlinings Jackets Jerseys Jumpers Kelims Kimono-look jackets Knitted jerseys Knitting yarn Knitwear Ladies’ wear Lamp covers (shades) Leg warmers Leisure wear Linings Machine-knitting yarns Mantle cloths Mats Men’s suits Menswear Mops Mourning scarves Mufflers Neck ties Neckwear Needle-punched carpets, blankets, etc Nets (laces and drapery materials) Nightgowns Nightwear Novelty yarns Oriental rugs Overcoats Paint brushes Paint rollers
Appendix 7 Mohair product list Palm Beach cloth Panama suits Persian carpets and rugs Pile fabrics (upholstery, etc) Plaids Plush fabrics Ponchos Pram hoods Press cloths (e.g. filters) Quilts Raincoats Residential upholstery Reversible lining Robes Roller brushes Rugs (prayer, etc) Runners (table, etc) Saddle blankets Scarves Scatter cushions Scatter rugs Seat covers (cars, trains, planes) Shawls Sheepskin covers (real and imitation) Sicilians Skirts Slippers Smoking jackets Snow and ski gear Socks Soft furnishings Soft furs Soft toys Soldiers’ uniform Sports clothes (knitted) Sports jackets Stoles Stuffed toys (pile fabrics, shaggy or cut) Sweaters Table covers (e.g. cloths, mats and runners) Tam-o’-shanters Tapestries Tapestry yarns Teddy bears Theatrical wigs Thigh-length cardigans
217
218
Appendix 7 Mohair product list
Ties Toilet covers Track suits Travel rugs Tray cloths Trench coats Trimmings (for coats, dresses, shoes, etc) Trunk linings Tunics Tweeds Tyre cords Underblankets Underlays Uniforms Upholstery Velours Velvets Waistcoats Wall covers Wall hangings Wigs and switches (e.g. for theatrical purposes) Women’s wear Wraps
Appendix 8 Rules for the use of the Mohair trade mark (label)
Knitting yarns/garments Gold Label – Yarns containing 70 % mohair and above. Not exceeding 27 mm – Superkid. – Yarns containing 70 % mohair and above. Not exceeding 32 mm – Kid. – Yarns containing 70 % mohair and above. 32 mm and higher – mohair.
Silver Label – Yarns containing 40 % mohair and above. Not exceeding 27 mm – Superkid. – Yarns containing 40 % mohair and above. Not exceeding 32 mm – Kid. – Yarns containing 40 % mohair and above. 32 mm and higher – mohair. Any other fibres constitute the balance in each case. Control is dependent upon appearance and handle as well as fibre composition. Micron tolerance is 21/2 %.
Ladies’ fabrics, blankets, scarves, etc – –
Gold Label – minimum of 70 % virgin mohair by weight. Silver Label – minimum of 25 % virgin mohair by weight.
In all cases, the balance of the fabric must be composed of natural fibres. A tolerance of a maximum of 10 % of other fibres in the fabric is permitted provided such fibres are for reinforcement or visible decorative effects.
Menswear fabrics Gold Label – Qualities containing 50 % or more mohair by finished weight, or, qualities containing at least 30 % of Kid mohair by finished weight – the Kid mohair conforming to the official IMA definition of Kid mohair (i.e. 32 mm or finer). – Silver Label – Qualities containing at least 25 % mohair by finished weight.
–
In all cases, the balance of the fabric must be composed of natural fibre. A tolerance of maximum of 10 % of other fibres (but not man-made fibres) in the fabric is permitted provided such fibres are for visible decorative effects.
219
Appendix 9 Trade environment database Scotland and China and cashmere trade (CASHMERE)
CASE NUMBER: 275 CASE MNEMONIC: Cashmere CASE NAME: Scotland and China and Cashmere Trade A. 1.
IDENTIFICATION The Issue
Since the Victorian Era, British textiles have been regarded among the world’s finest knits. Dawson International, Britain’s largest textile company, requires one metric ton of cashmere wool per day to operate, while Britain’s cashmere breeders produce less than one metric ton annually.1 Presently, China supplies 60 % of the world’s cashmere, which amounts to 3000 metric tons per year.2 With economic liberalization, growth in textile and apparel industries, and direct access to cashmere wool, the Chinese are encroaching upon the domain of the British knitters and rival the British for the limited supply of cashmere wool. With the limits of wool produced globally, the increased popularity of cashmere apparel, and the inexpensive textiles from China, Scotland is faced with the possibility of inadequate supplies of quality cashmere wool at elevated prices.3 While China seeks to expand markets and continue economic growth, Britain fights to maintain the cashmere supply at responsible prices while carrying on the tradition of high-quality woolen knitwear. Environmentally, the Scottish Highlands and the Himalayan regions of China will be impacted by increased herding, over-grazing, deforestation, and increased textile manufacturing. Within China, an environmentally unstable country, goat herding seems to attract little concern. More pressing environmental issues, such as elevated carbon dioxide levels and polluted water supplies, are the focus of a quickly modernizing China. 2.
Description
Cashmere cloth is prized for its softness, warmth, and long life. Cashmere fibers become increasingly soft with wearing and [it] is referred [to] as the Fiber of Kings.4 ‘Ring shawls,’ which are named for the process of pulling the shawl through a ring, are often passed down through the generations.5 In addition to its softness and flexibility, cashmere wool, which experts claim is eight times warmer than sheep’s wool, provides the necessary warmth for the harsh Himalayan climate.6 Although cashmere is no longer limited to royalty, a king’s ransom is required to buy cashmere
220
Appendix 9 Scotland and China and cashmere trade
221
with the current rate of $190 per pound for quality cashmere wool.7 The economic stakes, competition over the supply of cashmere, and its significance to China and Britain, is understandable. The name cashmere originates from the Kashmiri goats of the Himalayas. Cashmere wool is the downy undercoat that grows from midsummer to winter in varying quality by all goats.8 Long guard hair protects the cashmere undercoat from the elements and is removed in the spring by shearing or gradually combing the hair to remove the down.9 Each goat produces 3 to 8 ounces of cashmere down per year and the average single-ply women’s sweater requires the wool of 3 or 4 goats or approximately 10 ounces of wool.10 The quality of the wool is defined by the length, texture, and diameter of the fibers. These quality standards are affected by the climate in which the goats are raised and the nutrients that they consume.11 Mongolia’s climate and geography is suited for herding cashmere goats, who thrive in harsh dry mountainous climates and produce the highest quality of wool. In moderate climates, goats lose the ability to grow the downy coats that produce quality cashmere for garments.12 A significant quality differential exists between wool produced in Britain and the Himalayas. The British were content to import raw wool from China until the recent competition over the cashmere supply became a concern. Previously, Chinese wool producers brought raw wool to a central market to sell at set prices; however, this operation changed.13 With the economic liberalization of the mid-1980s, the mountain farmers were free to sell 25 % of their crops on the open market for cash.14 The transition towards a market economy removed the central authority that set prices, standards, and amount of wool sold in China. To replace the government control, middlemen entered the equation and capitalized on the new economic operations by exacting high prices from the Western buyers. As restraints are removed, the quality of the raw wool decreases and prices soar as much as 50 % in 1990. With the substantial price increase for raw materials, Dawson International, Inc., the largest British knitwear company, estimated that the volume of cashmere sweaters sold fell by 30 % in 1990.15 The increased interest in the market economy led Chinese industries to expand beyond raw materials to begin processing and spinning the raw wool into cheap alternatives to Scottish knits. These inexpensive garments have already entered the Asian markets and may begin to enter the Western markets, which poses a threat to the British textile industry. According to Dawson International, the problem is not that the Scots will have to compete with the Chinese, rather, the limited amount of cashmere available.16 With the lessening of governmental control over the economic forces, China began to evolve from a raw material supplier to a cloth and apparel producer. The changes in production diminished the amount of raw wool for sale to British textile firms without relying on the Chinese processing techniques.17 The British argue that the Chinese processing techniques ruin the length of the fibers, which (high-quality) woolen knits require. During the latter half of the nineteenth century, Joseph Dawson, the founder of Dawson International, perfected the processing of cashmere wool. Since Dawson invented this process, it has been a strictly guarded secret and remains unchanged.18 Liberalization efforts affected the Chinese economy. Fluctuations within the reform movement caused imbalances within the textile industrial structure. This
222
Appendix 9 Scotland and China and cashmere trade
hesitant reform process fragmented certain sectors such as spinning and weaving, which remained under government control through the Fall of 1991. As the Chinese government loosened its hold over the people, political turmoil has obstructed cashmere supplies, and prompted Britain to search for alternative sources of cashmere.19 Further, the industries will have to overcome obstacles that accompany an inadequate infrastructure, to allow goods to reach their export markets. The greatest threat to China’s burgeoning textile industry is the possibility of export market protectionism. The Sino-US bilateral textile agreement (under the Multi-Fiber Arrangement of 1985) was profitable for China through the 1980s.20 Beginning in 1988, trade restrictions intensified as the United States began to experience a slowdown in the economy and an increase in the federal and trade deficits; yet, China continued to supply over 12 % of the textile and apparel imports to the American markets. Within China, economic growth elevated the incomes of the workers, which benefited the textile and apparel industry through an expansion of the consumer base.21 Reports show that both imports of raw materials and exports of finished goods from China have multiplied since the initiation of economic reform measures. In the wake of economic liberalization, the Chinese made efforts to establish standards, price limits and trade laws to counter the problems of poor quality and fluctuating prices. In August of 1989, the State Administration for the Inspection of Import and Export Commodities instituted laws that serve to raise the quality of import and export commodities. China introduced and revised 19 laws and regulations throughout 1989 to increase the number of products that are inspected. Furthermore, the government has increased the number of inspection laboratories to increase examination abilities.22 With the large increase in the demand for cashmere and relaxed governmental controls, small local companies capitalized on the increased demand by selling inferior wool at inflated prices. These practices raised questions as to the reputation of China’s cashmere. In 1990, the Chinese government took steps to ensure quality standards and price uniformity within the textile industry. To improve the quality standards, the Ministry of Foreign Economic Regulations and Trade (MOFERT) established China’s Cashmere Foreign Trade Center to manage cashmere exports. The Center sponsors four trade fairs per year to sell cashmere, to set limits for export prices, and to issue licenses for the Center.23 Another measure to define economic policy was the textile export announcement that was issued on February 21, 1991 by the Chinese Ministry of Foreign Economic Relations and Trade. This announcement states that textile products produced in China or processed with imported materials require labels of origin, cannot exceed quota restrictions, and may not be exported to countries that have not signed bilateral agreements. Currently, bilateral agreements exist with the European Union, the United States, Canada, Norway, and Finland.24 With the projected growth of the textile and apparel exports and the institution of management and quality control measures, one believes that efficient practices and higher quality products will be forthcoming.25 As the economy of China changes, the British textile companies must search for alternative sources of cashmere wool to satisfy their supply requirements. The EU funded a project (£500 000) in Scotland to breed indigenous goats that would produce a comparable quality of cashmere fiber to that produced in China, Afghanistan, Iran, and Mongolia was initiated in the late 1980s. The projected outcome of the program would expand into an industry worth £5 million by 1997.26
Appendix 9 Scotland and China and cashmere trade
223
Additionally, Scottish Cashmere Producers Association (SCPA) initiated a program to ‘increase cashmere production by 25-fold within the next decade’ (2004). Presently, the SCPA produces no more than a metric ton of cashmere a year, which would not supply Dawson for a day. They offer incentives to farmers to raise goats. The Association provides ‘goatpacks’, which consist of 12 does and the hire of a buck for the breeding season.27 To protect the supply of cashmere coming to the British textile industries, joint ventures have been initiated in China. One joint venture in textile manufacturing is the Shanghai United Wooltex Corp. Ltd, the first joint venture in the textile and apparel industry, which started in 1981. This company began as a wool spinning and knitting operation and has expanded to develop goods, including cashmere garments, that target foreign markets.28 Another way the British are attempting to stave off the lesser quality inexpensive cashmere knits is based on expanded clothes lines, more boutiques, and enhanced marketing schemes.29 The challenge, however, remains to be the need for a continuing and reliable supply of wool, more so than a market for the garments. With the rise in demand for cashmere products, environmental repercussions will follow unless the farmers take measures to prevent overpopulation, deforestation, and become environmentally conscious. Goats are notorious for being indiscriminate eaters. In addition to grain and water, goats consume over 10 % of their body weight in roughage daily.30 With the land overstocked, the eating habits of the goats are likely to cause deforestation. In the arid Himalayan region, deforestation can kill pasture land, encourage the growth of weeds, initiate soil erosion, and desertification.31 Further, the increased breeding and raising of goats in Scotland, Australia, New Zealand, the United States, Iran, Afghanistan, Tibet, and Tasmania will impact the environment. In Scotland, the highland cattle are being forced to share the land and limited vegetation with increasing numbers of goats.32 With less food available, fewer nutrients will be consumed and the quality of the cashmere fibers will suffer.33 During the industrialization period, a large portion of Britain’s land was deforested for ship building and manufacturing. According to experts, goats may improve pasture land and aid reforestation by eating rough plants and brush.34 The danger, however, stems from the maximization of profit through increased herd sizes, which may result in environmental crises. The challenge to supply the markets with cashmere wool serves as a significant economic struggle to meet increasing demand and maximize profits. One must look beyond fashion and luxury of cashmere garments to the possible detrimental effects on the environment. 3.
Related Cases
CEDARS Case OTOMI Case ECFURBAN Case BABYSEAL Case Keyword Clusters (1): Trade Product = CASHMERE (2): Bio-geography = DRY (3): Environmental Problem = DEFORestation
224 4. B.
Appendix 9 Scotland and China and cashmere trade Draft Author: Theresa Purcell (May, 1996) LEGAL CLUSTERS
5.
Discourse and Status: In Progress
6.
Forum and Scope: China and Scotland and BILATeral
7.
Decision Breadth: 1 and China
8.
Legal Standing: TREATY
C. 9.
GEOGRAPHIC CLUSTERS Geographic Locations a. Geographic Domain: ASIA b. Geographic Site: WEST ASIA c. Geographic Impact: CHINA
10. Sub-National Factors: No Mongolia, Kashmir, Tibet economically center around herding animals (yaks, sheep, goats). The best cashmere is produced in these harsh mountainous regions and provides a source of income within the region. 11. Type of Habitat: DRY D.
TRADE CLUSTERS
12. Type of Measure: QUOTA, LICENsing, LAW Through China’s bilateral trade agreements, quotas were set, export licenses were instituted, and labels of origin were required on cashmere. Also, laws on inspection of import and export commodities were implemented August 29, 1990. 13. Direct vs Indirect Impacts: INDirect 14. Relation of Measure to Environmental Impact a. b. c. d.
Directly Related: NO Indirectly Related: YES GOAT Not Related: NO Process Related: YES DEFORestation
15. Trade Product Identification: Cashmere wool 16. Economic Data: China produces 3000 metric tons of cashmere per year at a current price of $.14 per pound (de-haired) or retail to spinners $12 per ounce. After spinning, cashmere is valued between $120 and $190 per pound. Currently, the highest quality of cashmere is being sold for more than $190 per pound. In 1989 revenues of $575 million were recorded by Dawson International, the leading British textile firm. The EU awarded £500 500 in 1987 for a ten year study on breeding goats for high quality cashmere. The projected worth of the project, based on increased quality of cashmere output, is estimated to be £5 million by 1997.
Appendix 9 Scotland and China and cashmere trade 17. Impact of Measure on Trade Competitiveness: 18. Industry Sector:
225
LOW
Textile and Apparel [TEXTAPP]
19.
Exporter and Importer: China and (Scotland) UK
E.
ENVIRONMENT CLUSTERS
20. Environmental Problem Type: DEFORestation 21. Name, Type, and Diversity of Species Name: Goat (pasang or bezoar) Type: Cashmere (originally from Kashmir and Tibet) Diversity: 300 varieties domestic goats 22. Impact and Effect: 23.
Urgency and Lifetime: LOW and 5–10 Years
24. Substitutes: F.
MEDIUM and PRODuct
SYNTHetic and LIKE
OTHER FACTORS
25. Culture: YES According to historical accounts, cashmere was used to line and cover the Ark of the Covenant. 26. Human Rights: NO 27. Trans-Border: NO 28. Relevant Literature ‘Better quality of imports & exports’, Beijing Review, September 17–23, 1990:42. Fetzer, Scott. ‘Goat’, World Book Encyclopedia, vol 8, 239–42. ‘First joint venture makes much headway’, Beijing Review, September 9–15, 1990:38–9. ‘Goat Facts’, http://infopages.com/ocfair/goat.htm ‘Hairy and horny’, The Economist, August 20, 1994:54. Harris, John. ‘Cashmere Goats’, http://www.ics.uci.edu/~pazzani/4H/Cashmire.html Lubove, Seth. ‘As the worms turn’, Forbes, May 19, 1990:76–9. Marcom, John Jr, ‘$1,600 sweaters, anyone?’ Forbes, May 14, 1990:116–17. Rasin, Steve. ‘Off and running’, The China Business Review, September–October, 1991, 34–8. ‘Scientists to clothe goats in cashmere coats’, New Scientist, July 23, 1987, 18. Taylor, Ian Lance. ‘Black Locust Farm’, http://www.cyprus.com/~ian/black-locustfarm.html
226
Appendix 9 Scotland and China and cashmere trade
‘Textile export announcement’, Beijing Review, March 18–24, 1991, 40. United States Agriculture Department, ‘Cashmere Goats’, http://www.inform.umd.edu:8080/EdRes/Topic/AgrEnv/ndd/goat/Cash United States Agriculture Department, ‘Feeding’, http://www.inform.umd.edu:8080/EdRes/Topic/AgrEnv/ndd/goat/Feed1 ‘Who put cash in cashmere?’, Newsweek, December 1, 1986, 70. Yuan, Zhang. ‘Better management of cashmere exports’, Beijing Review, September 23–9, 1991, 42. References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
Economist, 8/20/94, 54. http://www.ics.uci.edu/~pazzani/4H/Cashmire.html; Economist, 8/20/94, 54. Marcom, 5/14/90, 116–17. http://www.inform.umd.edu:8080/EdRes/Topic/AgrEnv/ndd/goat/Cash http://www.cyprus.com/~ian/black-locust-farm.html ibid. http://www.ics.uci.edu/~pazzani/4H/Cashmire.html http://www.cyprus.com/~ian/black-locust-farm.html http://www.cyprus.com/~ian/black-locust-farm.html; Newsweek 12/1/86, 70. http://www.cyprus.com/~ian/black-locust-farm.html; Marcom, 5/14/90, 116–17. http://www.inform.umd.edu:8080/EdRes/Topic/AgrEnv/ndd/goat/Cash; Newsweek 12/1/86, 70. Newsweek 12/1/86, 70. ibid. Lubove, 76. Marcom, 5/14/90, 116–17. Economist, 8/20/94, 54. ibid. Marcom, 5/14/90, 116–17. http://www.inform.umd.edu:8080/EdRes/Topic/AgrEnv/ndd/goat/Cash Rasin, Steve, China Business Review, Sept./Oct. 1991, 34–38. ibid. Beijing Review, 9/17–23/90, 40. Yuan Zhang, Beijing Review, 9/23–29/91, 42. Beijing Review, 9/18–24/91, 40. Yuan, Zhang, Beijing Review, 9/23–29/91, 42. New Scientist, 7/23/87, 18. Economist, 8/20/94, 54. Beijing Review, 9/9–15/91, 38–39. Marcom, 5/14/90, 116–17. http://www.infopages.com/ocfair/goat.htm http://www.cyprus.com/~ian/black-locust-farm.html Economist, 8/20/94, 54. http://www.inform.umd.edu:8080/EdRes/Topic/AgrEnv/ndd/goat/Feed1 http://www.inform.umd.edu:8080/EdRes/Topic/AgrEnv/ndd/goat/Cash
Appendix 10 Quality assessment of goat hair for textile use KIM-HÔ PHAN, F.J. WORTMANN Deutsches Wollforschungsinstitut DWI (German Wool Research Institute) Veltmanplatz 8 D-52062 Aachen – Germany
SUMMARY The paper shortly describes changes that have occurred in the production of goat hairs, especially cashmere, for textile use as well as in the structure of the processing industry in the last 2 decades. Attempts are made to classify different types of goat hair according to their origins and their characteristics. Factors affecting price of goat hair are cited. Technical methods for the evaluation of goat hair are presented. Problems of fraudulent labelling of cashmere garments are discussed. 1. PRODUCTION OF GOAT FIBRE FOR TEXTILE USE 1.1 Mohair: fibre of Angora goats living in South Africa, Texas/USA and Turkey. The world total production has decreased from ca. 21 000 t in 1986 to approximately 7500 t in 1999, whereby 60 % (4500 t) originate from South Africa.1 1.2 Cashgora (Cash = cashmere, gora = Angora): this is a natural fibre type produced by cross-breeding an Angora goat with a feral goat (in New Zealand since the mid-1980s) or with a cashmere goat (in Iran, Mongolia, Kazachstan). The production of Cashgora was approximately 50 t in 1986, but has sharply decreased since the customers’ acceptance for this fibre type has remained reserved. 1.3 Cashmere: fine undercoat fibre (down) of cashmere goats. – Traditional sources: China, Mongolia, Himalayan regions (local name: Pashmina), Afghanistan, Iran (coarser qualities), Kazachstan, Kirghiz, Uzbekistan (Cashgora type). – New sources: Australia/New Zealand, Scotland, since the early 1980s. The world total production of cashmere is estimated at ca. 6000 t in 1998, mainly in China, Mongolia, Iran, Afghanistan. Attempts to breed goats bearing fine undercoat fibres have also been made in the USA (Colorado), South Africa (KwazuluNatal)2 and in some other European countries (Spain, Italy, Norway). 2. CASHMERE PROCESSING The most crucial step in cashmere processing – the industrial dehairing process – was invented by Dawson in Scotland during the latter half of the 19th century and it has been a strictly guarded secret. Until the 1970s, only a few European companies had mastered this technique, so that the Asian cashmere producers had to export most of their raw material to Europe for dehairing and processing into high quality garments. Since the economic liberalisation, Chinese as well as Mongolian companies have co-operated with Japanese counterparts and successfully boosted the local cashmere dehairing and processing industry. Mongolia actually enacted an
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embargo on raw cashmere export to support the establishment of local cashmere enterprises. The 1980s also witnessed European and American cashmere industry’s efforts in protecting the cashmere raw material supply which had become a problem. Joint ventures have been established in China and Mongolia by renowned Western enterprises. Nowadays China has developed its dehairing and garment making industry to the point of over-capacity. By the end of 1996, China had approximately 2000 cashmere-knitwear producers with a total processing capacity of 15 000 t of raw cashmere a year.5 3. CLASSIFICATION OF GOAT FIBRES 3.1 Mohair: according to the mean fibre fineness, mohair is generally classed into Kid mohair (Fine Kid, Good/Average Kid), Young Goat and Adult mohair. 3.2 Cashgora: the mean fibre fineness of this fibre type ranges from 18 to 23 mm. 3.3 Cashmere: contrary to mohair, cashmere originating from various regions of the world shows a pronounced diversity. In the following more details are described because cashmere is the most expensive generic type among the speciality fibres (except vicuña) for textile use. 3.3.1 Mean fibre diameter MFD (mean fibre fineness): Chinese cashmere is the finest (14–16.5 mm). Mongolian is fine, but is currently becoming coarser due to intensive cross-breeding for increased yield (up to 17–18 mm). Iranian/Afghan cashmere is 2–3 mm coarser than Chinese cashmere (17–19 mm). Cashmere from New Zealand/Australia is generally coarse (17–17.5 mm), ‘with perhaps 30 % of the clips being under 16.5 microns, and with virtually no cashmere in the traditional high quality knitwear range of 15 to 15.5 microns’.7 In well dehaired samples, the individual diameter of cashmere fibres varies from 8 mm to 24–25 mm. Besides some coarse Iranian/Afghan samples having an MFD of ca. 20 mm, the upper threshold of the MFD observed for most commercial samples has usually been 19 mm. In conformance with the fibre qualities on the market, the upper limit for the MFD of cashmere has therefore been set at 16.0 (+0.5) mm by the Chinese National Standard,6 at 18.5 ± 0.5 mm by the CCMI (Cashmere and Camel Hair Manufacturers Institute, the trade organisation of reputable companies in the USA, Europe and Japan), at 18.5 mm by the AATCC3 (American Association of Textile Chemists and Colorists) and at 19 mm by the ASTM4 (American Society for Testing and Materials), both in the USA. In the last few years, coloured goat hairs having an MFD of 20–26 mm have also been sold on the German market as cashmere as well. It is worth noticing that these coarse qualities cannot be recognised as cashmere according to the current regulations. Only fine cashmere type up to 15.5 mm has been used for high quality knitwear. The coarser qualities from Iran/Afghanistan, New Zealand/ Australia (up to 19 mm) are generally used in the weaving industry. 3.3.2 Mean fibre length: fine undercoat fibre of Chinese cashmere raw material has a mean fibre length between 21 mm and 40 mm (super grade). The individual fibre fineness runs from 5 mm to 80–90 mm, depending on the quality of the sample being investigated. 3.3.3 Colour: dehaired cashmere raw material from China/Mongolia as well as from Iran/Afghanistan has shades of white, light grey, dark grey and brown. Cream, fawn and dark brown are typical colours for Iran/Afghan cashmere. 3.3.4 Surface morphology: classical Asian cashmere exhibits quite similar surface structures despite the different goat strains. The typical cylindrical and semicylindrical scale shapes are regular and usually have a mean scale frequency (i.e. number of scale shapes per 100 mm fibre length) of 6–7. Cashmere from the new
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sources shows quite different scale shape on the fibre surface compared to that of the Asian types.14,15,16,20 The fibres usually have a higher scale frequency (more than 8) and look more complex, resembling the surface morphology of mohair. This is perhaps the reason for their highly lustrous, slippery character and comparatively harsh handle. It is also responsible for problems during processing these fibre types, as described by the purchaser of 60 % of the Australian production, 40 % of New Zealand and 100 % of the USA.7 At DWI, this fibre type has been classified as ‘crossbred-cashmere’.16 In the last few years, an increasing number of cashmere samples from Outer Mongolia and Iran being investigated at DWI have been classified as ‘crossbred-cashmere’. Samples coarser than 20 mm have been classed as ‘Cashgora’. 4. FACTORS INFLUENCING PRICES OF DEHAIRED PURE CASHMERE The mean fibre diameter is a very important characteristic for the value of cashmere products. The finer the fibre, the smoother is the handle and the lighter the weight of the cashmere. The difference of 2–3 mm in MFD between Chinese cashmere (ca. 15 mm) and Iranian/Afghan cashmere makes the former approximately 50 % more expensive.The natural colour also influences its value greatly.White is the most expensive, because dark cashmere must usually be bleached before dyeing, particularly in pastel colours. Worsted yarn can only be spun when the mean fibre length is high enough. Lots with short fibres must therefore be spun on carded system. Other factors affect the price of dehaired cashmere raw material: the more of the coarse hairs and other contamination (dandruff etc.) that had been removed, the purer the cashmere, the more expensive it is. 5. MEASURING THE CHARACTERISTICS OF GOAT HAIR 5.1 Mean fibre diameter: various instruments can be used to measure mean fibre fineness. The most common and affordable tool has been the projection microscopy according to IWTO-8-97 of the IWTO (International Wool Textile Organisation) and the Airflow method according to IWTO-6-98.9 Two modern techniques have been standardised but require expensive instruments: the Sirolan-Laserscan Fibre Diameter Analyser according to IWTO-12-98 and the OFDA (Optical Fibre Diameter Analyser) according to IWTO-47-95, whereby several thousand fibres can automatically be measured.9 Two further techniques are not standardised, the scanning electron microscopic (SEM) and the cross-sectional (CS) method. Besides the MFD the coarse hair percentage of the sample can also be determined. 5.2 Fibre length: the mean fibre length can be determined according to the standardised test methods, such as IWTO-Draft TM-5-97 using a single fibre length measuring machine, IWTO-17-85 using an Almeter and IWTO-16-67 using a WIRA Fibre Diagram Machine.9 6. PROBLEMS OF FIBRE ADULTERATION Stringent labelling regulations for textile products at all stages of processing compel the manufacturers to state not only the types of fibres but also their weight percentages contained in their goods. Despite the regulations, substantial price differences of wool and speciality fibres, especially cashmere, have been the incentive for mislabelling for all forms of textile products. The current market prices of keratin fibres for textile use vary from approx. 3–5 USD/kg for sheep’s wool to an amount of 100 USD/kg for first grade Chinese cashmere. It is therefore not surprising that well over 60 % of the textile samples containing speciality fibres investigated at DWI
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between 1990 and 1999 were found to be mislabelled. For decades the cheaper generic type has been blended with the expensive one without declaring the true fibre content of the garments. In cashmere and cashmere blend garments, sheep’s wool has long been identified as substitute. Even the almost worthless recycled wool fibres being regenerated from rags or waste have also been declared as cashmere. But yak,Angora rabbit and camel hair have also been identified as adulterants. High prices and short supply worsen the situation. The problem of mislabelling is so widespread that CCMI has regularly purchased garments at stores in a variety of cities across the USA and tested individual garments for accuracy of labelling. It has been estimated that 15 % of garments claiming to contain genuine cashmere and cashmere blend are indeed mislabelled.19 Another severe problem has been highlighted after international round trials being organised by CCMI in the last few years: some well-respected laboratories specialising in the analysis of animal fibres failed to quantify blind samples of known composition and origin.17,18 As a consequence, CCMI has recommended only a few of the laboratories as being able to offer reliability.8 7. FIBRE IDENTIFICATION Contrary to synthetic fibres, all animal fibre types for textile use are very similar regarding their chemical and physical properties, so that light microscopy was the most commonly used method for recognising animal fibres until the beginning of the 1980s.11,20 Although the method has been standardised in the USA,3,4 its accuracy has up to the present not been satisfactory for the demand of the textile industry. Since the introduction of the scanning electron microscope (SEM) by DWI,10,14–16,21–23 ‘topographic fingerprints’ of each generic fibre can be revealed which cannot be seen using the light microscope. Besides the MFD, three other criteria of the surface structure are decisive for fibre identification and analysis: the height of the cuticle scale edge (the most important criterion for distinguishing sheep’s wool on one side and all other speciality fibres on the other side), the mean scale frequency and the scale appearance. With the aid of the SEM, mohair and cashmere of different origins can be differentiated and classified.14,15 The SEM method was recognised as a Draft Test Method (DTM-58-97) for the quantitative analysis of blends of sheep’s wool with other speciality fibres by the IWTO in 1997.9 Besides the routine LM and SEM method, the DNA profiling techniques13 and the gel electrophoresis method12,24 can also be used for fibre identification, but the textile processing steps (bleaching, dyeing) can negatively affect the analysis results. References 1 Anon., Wool Record 12 (1999) 37 2 Anon., Wool Record 11 (1998) 33 3 AATCC Test Method 20, ‘Fiber Analysis: Qualitative’ (revised 1998) and Test Method 20A ‘Fiber Analysis: Quantitative’ AATCC Technical Manual 65: 67 (1990) 4 ASTM Method D 629–95, ‘Test Methods for Quantitative Analysis of Textiles’, American Society for Testing and Materials, Part 33 ASTM Philadelphia (1995) 5 Chen Ya, Wool Record 11 (1997) 55 6 Chinese National Standard FZ/T 21003-1998 7 Hopkins H., ‘International Economics and Marketing’, in New Developments in Goat Husbandry for Quality Fibre Production (1992) 13–140, Seminar Proceedings (ed.) Dr. Galbraith, Univ. Aberdeen, UK
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8 http://www.cashmere.org/html/testing_labs.html 9 IWTO-8-97; IWTO-6-98; IWTO-12-98; IWTO-47-95; IWTO-16-67; IWTO-17-85; IWTO-Draft TM-5-97; DTM-58-97; The Woolmark Company, Techn. Marketing Department, Ilkley, UK 10 Kusch P., Arns W., ‘Scanning electron microscopic investigation to distinguish between sheep wool and goat hair’ Melliand Text. Ber. 64 (1983) 427 11 Langley K.D., ‘Light microscopy, of fine animal fibres revisited: limitations and opportunities’, Europ. Fine Fibre Network, Occas. Pub. No. 4 (1996) 27 12 Marshall R.C., Zahn H., Blankenburg G., ‘Possible identification of specialty fibers by electrophoresis’, Text. Res. J. 54 (1984) 126 13 Nelson G., ‘DNA-based diagnostics of speciality animal fibre’, Text. Technol. Intern. (1997) 110 14 Phan K.-H., ‘Electron Microscopy and the Characterization of Keratin Fibres’, Ed. EEC Comett Eurotex, Univ. do Minho/Guimara¯es, Portugal (1991) 15 Phan K.-H., ‘Neue Erkenntnisse über die Morphologie von Keratinfasern mit Hilfe der Elektronenmikroskopie’, Ph.D. Thesis RWTH Aachen,Germany (1994) 16 Phan K.-H., Wortmann F.-J., ‘Identification and classification of cashmere’, Europ. Fine Fibre Network, Occas. Pub. No. 4 (1996) 45 17 Phan K.-H., Wortmann F.-J., ‘Microscopic Analysis of Wool/Cashmere Blends – Results of the 1995 CCMI Round Trial’, Proceedings of a Conference of the Int. Wool Text. Org., Technical Committee, Report No. 25, Boston (1997) 18 Phan K.-H., Wortmann F.-J., ‘Microscopic Analysis of Wool/Cashmere Blends – Results of the 1997 CCMI Round Trial’, Proceedings of a Conference of the Int. Wool Text. Org., Technical Committee, Report No. 11, Nice (1997) 19 Spilhaus K., ‘Enforcing trading standards in cashmere and camel hair marketing’, Europ. Fine Fibre Network, Occas. Pub. No. 4 (1996) 21–25 20 Wildman A.B., ‘The Microscopy of Animal Textile Fibres’, Wool Ind. Res. Assoc., Leeds, England (1954) 21 Wortmann F.-J., Arns W., ‘Quantitative Fiber Mixture Analysis by Scanning Electron Microscopy – Part I: Blends of Mohair and Cashmere with Sheep’s Wool’, Text. Res. J. 56, 7 (1986) 442 22 Wortmann F.-J., ‘Limits of accuracy for the microscopic analysis of animal fibre blends’, Europ. Fine Fibre Network, Occas. Pub. No. 4 (1996) 135 23 Wortmann F.-J., Wortmann G., ‘Scanning Electron Microscopy as a Tool for the Analysis of Wool/Specialty Fiber Blends’, Ed. EEC Comett Eurotex, Univ. do Minho/Guimarães, Portugal (1991) 24 Wortmann G., Wortmann F.-J., ‘Chemical characterization of fine animal hair’ in Proceedings of the 1st Int. Symp. on Special. Animal Fibres, Schriftenreihe DWI 103 (1988) 39 Selected Publications Concerning Speciality Fibres Phan K-H, Wortmann F-J, ‘Aspects on the Morphology of Cashmere and Yak Fibers’, Schriftenreihe des DWI 101 (1987) 137 Phan K-H, Wortmann F-J, Arns W, ‘Bivariate, Microscopic Characteristics for the Identification of Speciality Fibres’, Schriftenreihe des DWI 102 (1988) 83 Phan K-H, Wortmann F-J, Wortmann G, Arns W, ‘Characterization of Speciality Fibres by Scanning Electron Microscopy’, Schriftenreihe des DWI 103 (1988) 137 (Paper presented at the 1st International Symposium on Specialty Fibers,Aachen, 1987)
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Wortmann F-J, Wortmann G, Arns W, Phan K-H, ‘Analysis of Speciality Fibre/Wool Blends by Means of Scanning Electron Microscopy (SEM)’, Schriftenreihe des DWI 103 (1988) 163 Phan K-H, Wortmann F-J, Arns W, ‘On the Morphology of Cashgora Fibres’, Schriftenreihe des DWI 105 (1990) 135 Phan K-H, Wortmann F-J, Arns W, ‘Cashmere! Cashmere?’, Schriftenreihe des DWI 108 (1991) 235 Phan K-H, Arns W, Wortmann F-J, Höcker H, ‘Cashmere – An operational Definition’, Int. Wool Text. Organ.-Report No. 4, Lisbon (1991) Phan K-H, ‘Identification and Classification of Cashmere’, in ‘Metrology and Identification of Speciality Animal Fibres’, Ed. Laker JP and Wortmann F-J, Europ. Fine Fiber Network, Occas. Publ. No. 4 (1996) 45–58 (Paper presented at the 3rd International Symposium on Specialty Fibers, Aachen, 1995) Phan K-H, ‘Structure of the Cuticle of Fine Wool Fibres’ Proc. 9th Int. Wool Text. Res. Conf. II, Biella/Italy (1996) 19 (Paper presented at the 9th International Wool Textile Research Conference, Biella/Italy, 1995) Phan K-H, Wortmann F-J, Arns W, ‘Characterization of Cashmere’, Proc. 9th Int. Wool Text. Res. Conf. II, Biella/Italy, (1996) 571 (Poster presented at the 9th International Wool Textile Research Conference, Biella/Italy, 1995) Phan K-H, Wortmann F-J, ‘Quantitative Analysis of Blends of Wool with Speciality Fibres by Scanning Electron Microscopy’, Int.Wool Text. Org., Report No. 10, Nice (1996) Phan K-H, Wortmann F-J, ‘Quantitative analysis of blends of wool with speciality fibres by scanning electron microscopy’, 2nd Draft, Int. Wool Text. Org., Report No. 24, Boston (1997) Phan K-H, Wortmann F-J, ‘Microscopic analysis of wool/cashmere blends – Results of the 1995 CCMI round trial’, Int. Wool Text. Org., Report No. 25, Boston (1997) Phan K-H, Spilhaus K, Wortmann F-J, ‘Microscopic analysis of wool/cashmere blends – Results of the 1997 CCMI round trial’, Int. Wool Text. Org., Report No. 11, Nice (1997) Phan K-H, Souchet C, ‘Presentation of the first results of the Round Trial on fineness of cashmere and mohair’, Europ. Fine Fibre Network, Workshop Rep. No. 3 (1998) 3 Wortmann F-J, Phan K-H, ‘Cuticle Scale Heights of Wool and Specialty Fibers and their Changes Due to Textile Processing’, Text. Res. J. 69(2), 139–144 (1999) Phan K-H, Wortmann F-J, ‘Recommended Changes to DTM-58: Quantitative Analysis of Blends of Wool with Speciality Fibres by Scanning Electron Microscopy’, IWTO – Report No. STG 01, Nice (1999) Phan K-H, Wortmann F-J, ‘Quality Assessment of Goat Hair for Textile Use’, Proc. 7th Int. Goat Conf., Tours/France (2000) 631 Wortmann F-J, Phan K-H, “Recommended Changes and Supplements to DTM-58: Quantitative Analysis of Blends of Wool with Speciality Fibres by Scanning Electron Microscopy” for Upgrading to a full Test Method’, IWTO – Report No. STG 01, Nice (2000) Phan K-H, Wortmann G, Wortmann F-J, ‘Microscopic Characteristics of Shahtoosh and Its Differentiation from Cashmere/Pashmina’, Proc. 10th Int. Wool Text. Res. Conf. XX, Aachen/Germany (2001) (in press) (Paper presented at the 10th Intern. Wool Text. Res. Conf., Aachen, 2000)
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Wortmann G, Phan K-H, Wortmann F-J, Electrophoretical Differentiation of fine animal hair: Shahtoosh, Proc. 10th Int. Wool Text. Res. Conf. xx, Aachen/Germany (2001) (in press) Booklets Phan K.-H. ‘Electron Microscopy and the Characterization of Keratin Fibres’, Ed. EEC Comett, Universidade do Minho, P-4800 Guimarães (1991) 1–72 Phan K.-H. ‘Neue Erkenntnisse über die Morphologie von Keratinfasern mit Hilfe der Elektronenmikroskopie’, Dissertation RWTH Aachen, ISBN 3-930085-72-0, Verlag Mainz, Aachen (1994) 1–132
Appendix 11 Luxury flame retardant fabrics for aircraft applications A RICHARD HORROCKS AND BALJINDER K KANDOLA Bolton Institute, Bolton BL3 5AB, UK and
JOYCE DALTON AND TIM OWEN Dalton Lucerne Rare Fibres, Macclesfield SK10 5RU, UK
Abstract The increasing markets for executive jets and boats are mirrored by the demand for luxury fabrics used in their interior furnishings. Recent changes in US Federal (and other national) Aviation Authority (FAA) regulations, which now demand high level of fire resistance, have created a paradoxical situation where formerly acceptable fabrics fail the new specification and fabrics which do pass fail to have the desired level of aesthetic quality. Consequently, there is a need for fibres and fabrics that can combine the highest levels of technical performance with aesthetic character. Surprisingly, cost is often not a constraining factor in selection of fibre type and fabric structure; the challenge lies in finding the combination of excellent aesthetic and fire performance properties. Textiles used inside commercial and now executive aircraft have to pass the stringent flammability requirements defined by the FAA specification FAR 25.853 Part IV Appendix F and, by international agreement, all national aviation authorities subscribe to these regulations. At the present time only a few fabrics having the desired aesthetic quality, notably those developed by Dalton Lucerne, UK, which comprise exotic animal hair fibres such as mohair, alpaca and cashmere, have achieved the high levels of fire performance demanded. The particular success of these fabrics lies in their ability to pass the heat release requirements using the Ohio State University (OSU) calorimeter. This paper will describe the challenges faced by the designers of such fabrics and the means by which passing the FAA specification FAR 25.853 Part IV Appendix F has been achieved to date.
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Introduction Aeronautics is a world-class industry within Europe which in 1996 produced a trade balance of E 8bn. Corporate and private customers represent 53.7 % of the entire aviation market in units and Allied Signal (avionics manufacturer) forecasts that business aircraft sales will reach 6800 units valued at £89 billion in the period 1999–2009 (1998 estimates 6500 units worth $78 billion).1 European completion centres are increasingly being used to furnish American private jets, because American centres have severe production backlogs. Fabric spend per aircraft can be £20–30 K. Textiles used inside commercial aircraft have to pass the stringent flammability requirements defined by the Federal Aviation Authority and, by international agreement, all national aviation authorities subscribe to these regulations. Fabrics developed during the last 12 years or so require the use of extremely fire resistant fibres such as the aromatic polyamides, including Nomex (Dupont) and Kermel (Rhodia, formerly Rhône Poulenc) used alone or in blends with flame retardant wool. The balance between fire performance and aesthetics is acceptable for commercial use including first-class areas. Recently, the US Federal Aviation Administration (FAA) (and hence international) fire science performance tests relating to seating materials have been extended to all textiles present in interiors of private and commercial aircraft designed to carry more than 19 persons. This has created a demand for high performance in a market where luxury and aesthetics predominate and where cost is of minor importance. These regulations now include both the smaller executive jets and larger jets customised to carry only a few passengers. The fabrics used by commercial airlines even in first-class accommodation are of too low an aesthetic quality to suit this select but expanding market. In order to exploit this new market, Dalton Lucerne Rare Fibres, UK, have developed a range of exotic animal hair fibre weft yarns, woven on polyester or silk warps, for use in luxury jets, and these pass the fire performance demands set by the FAA specification, FAR 25.853 Part IV Appendix F.2 Recently Dalton Lucerne have been named in the UK as a Millennium Product Company because of the novelty and innovative character of their current fabric range. This paper discusses the burning behaviour of this range of fabrics in terms of heat release (using the Ohio State University calorimeter3) and the smoke and toxic gas emissions using the ‘National Bureau of Standards (now NIST) Smoke Test’.4
Burning behaviour of exotic animal hair-containing fabrics The use of wool and its flame retarded variants is well-established in the commercial aircraft field since the latter used alone or both forms blended with inherently fire-resistant aramid and similar fibres will enable heat release peak and average values to be below the required 65/65 kW m-2 upper limits.2 This is a consequence of the excellent low flammability of wool even when not flame retardant treated as shown by a relatively high LOI value of about 25 and a low flame temperature of about 680 °C. Its similarly high ignition temperature of 570–600 °C is a consequence of its higher moisture regain (8–16 % depending upon relative humidity), high nitrogen (15–16 %) and sulphur (3–4 %) contents and low hydrogen (6–7 %) content by weight.5
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Appendix 11 Luxury flame retardant fabrics Table A11.1 Principal amino acid contents and elemental constitutions of wool and mohair fibres6 Property Elemental analyses: Sulphur, % w/w Nitrogen, % w/w S-containing amino acids: Cystine, % w/w
Wool
Mohair
3.3–3.6 16.6
2.9–3.6 16.6
10.4–11.8
10.4
The very similar, but aesthetically superior mohair fibres, while being produced from Angora goats, might be expected to have similar flammability properties. The mohair fibre is typified by its high lustre, which coupled with its fineness and handle, provides fabrics having exceptional visual and physical aesthetics. The inherent flammability of all animal hair fibres is considered to be in part determined by their high nitrogen and sulphur contents as suggested above. Table 1 gives comparable selected amino acid and elemental contents for both wool and mohair.6 Mohair has slightly lower cystine and hence lower sulphur contents than wool fibres and the reported limiting oxygen value for the former is 246 compared with the value of 25 for wool. These values reflect a reasonable and similar level of inherent flame retardancy. To date, however, mainly because of its cost, mohair has not found its way into aircraft fabrics although previous attempts to flame retard it have been as effective as for wool.6 Alpaca fibres are produced from species of llama, principally the llama, guanaco and vicuña. Fibres from the vicuña are the finest, and because they have very smooth exterior surfaces they are similar to the mohair fibre in terms of aesthetic properties. Little, if any, data on the flammabilities of these fibres exist, however.
Heat release properties of animal hair-containing fabrics using the OSU calorimeter The results presented in this paper are those form a series of exotic animal haircontaining fabrics tested usually as a fabric-faced aramid fibre-based honeycombstructured board, representative of aircraft panelling composites.
Mohair fibre, yarn and fabrics Mohair fibres from angora goats (see Fig. A11.1) were spun into 20 s (worsted count) worsted yarns and woven on cotton, silk or polyester warps to yield plain or patterned (having a fleur-de-lis motif) fabrics having nominal area densities of about 150 g m-2 (6 oz yd-2). These fabrics were finished by standard commercial methods to remove warp size and adventitious impurities prior to further treatment (see below). A similar fabric with an alpaca weft and silk warp was also woven. Examples of these finished fabrics are shown in Fig. A11.2 to illustrate their level of aesthetic quality.
A11.1 An adult, full pedigree, Texan Angora goat.
A11.2 Typical luxury mohair fabrics for aircraft interiors.
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Table A11.2 Fabric samples and derived composites and associated treatments Sample
Backcoat
Mohair (61 %)– silk (39 % as warp): plain weave MS1 MS2 MS3 MS4 MS5 Mohair (61 %)– silk (39 % as warp): fleur-de-lis motif MSF1 MSF2 MSF3 Mohair– polyester (warp) MP1 MP2 MP3 MP4 Mohair–cotton (warp) MC1 Alpaca (60 %)– silk (40 % as warp) AS1 AS2
Adhesive
Board
✓ ✓ ✓ ✓ ✓
✓ ✓ ✓
S-SSCP* S-SSCP* Airbus
✓ ✓ ✓
✓
S-SSCP*
✓ ✓ ✓ ✓
✓ ✓ ✓
S-SSCP* S-SSCP* S-SSCP*
Al foil
FR1/ FR1/ board fabric face
✓
✓
✓
✓ ✓
✓ ✓ ✓
✓ ✓ ✓ ✓
✓ ✓ ✓ ✓ ✓
✓
S-SSCP*
✓ ✓
Note: * this denotes the board type produced by Schneller, Inc.
Sample preparation Normally, fabrics used as decoration for wall panels will be tested as fabric-faced composites on standard aramid honeycomb board such as is specified by an aircraft manufacturer (e.g. Airbus Industrie) or a board manufacturer (Schneller Inc, Ohio, USA). In order that fabrics could adhere to these boards, they were treated with a proprietary back-coating formulation based on an antimony/brominecontaining resin. The proprietary adhesive was applied to the back-coated face enabling it to adhere to the board. In some cases, a thin (0.025 mm) aluminium foil was sandwiched between the back-coated face and the board. Once the final composite had been produced, it could be tested with and without the application of an amount of a proprietary ammonium salt-based semi-durable flame retardant equivalent to 1–2 % by weight phosphorus on fabric. A limited selection of fabrics (mohair weft-cotton warp plain and fleur-de-lis) were exposed as free fabrics in the absence and in the presence of the flame retardant FR1 and tested with warp and weft yarns vertically within the OSU calorimeter. Table A11.2 lists the fabric
Appendix 11 Luxury flame retardant fabrics
239
samples used, the derived composites and both component and composite treatments used to produce final samples for testing.
Sample heat release results following exposure to OSU testing2,3 Experience has shown that in order for a fabric/board composite to achieve a pass with peak release rate <65 kW m-2 and a 2 minute average heat release rate <65 kWm-2 min-1 under OSU conditions (i.e. heat flux = 35 kW m-2), the choice of adhesive and back-coating are critical and that a final spray treatment of a flame retardant was necessary. The samples in Table A11.2 have been selected and constructed to indicate the importance of elements of these selection criteria and Table A11.3 presents the heat release results for these. OSU results for composites, according to the standard procedure,2 were undertaken at the testing facility at Avro International Aerospace, Woodford, UK; fabric results were obtained on the facility at Hexcel Composites Ltd, Duxford, UK. Peak heat release (PHR) and time to PHR: The influence of the differing warp types is shown by comparing sample PHR values for MS2 (silk warp), MP1 (polyester warp) and MC1 (cotton warp) where the last with a highest value of 88 kW m-2 suggests the influence of the highly flammable cotton present. The alpaca–silk combination (AS1) has a similar value which may indicate a poorer inherent flame resistance of this fibre compared to mohair. The effect on PHR of adding the flame retardant to a back-coated-free fabric is minimal and is shown by comparing the mohair–silk fabrics MS1 and MS2; a slight increase occurs, however, for the fleur-de-lis versions (MSF1 and MSF2) with the value rising from 55 to 61 kW m-2. Once a fabric adheres to an aramid board as shown in the results for MS3, there is a rise in PHR. This is supported by comparing samples of free (MP1) and mounted (MP2) mohair–polyester fabrics where PHR rises from 58 to 67 kW m-2; this is probably a consequence of the adhesive present, although slight reductions in mounted fabrics occur for mohair–silk fleur-de-lis and alpaca–silk fabrics. If the board is pretreated with flame retardant, then some of the lowest PHR values are seen for a given composite (e.g. MS4 and MP3). Exchanging a Schneller S-SSCP board for an Airbus analogue (compare MS4 and MS % results) seems to decrease favourably PHR values. The time to PHR is far less sensitive to the composite variables with only the adherence of the fabric to the support board producing a consistent increase in time. Similarly, replacement of the relatively thin S-SSCP board (3 mm) with the thicker Airbus board (7 mm) increases the time from 21 s (MS4) to 39 s (MS5). It would seem, therefore, that the increased sample thickness, mass and hence heat capacity may be a determining factor here. Two-minute average heat release (AHR): Average heat release (AHR) values over the first two minutes exposure period reflect the total fuel content of samples and so free fabric values (MS1, MS2, MSF1, MP1 and AS1) are considerably less than those for fabric/board composites. The conversion to a composite raises AHR values close to the limit of 65 kW m-2 min-1 and this is not affected by the presence or absence of flame retardant addition to the board. Lowest values, which often determine whether a composite passes or fails, are shown for samples which have the Airbus (thicker) board (MS5) or insertion of aluminium foil (MP4).
240
Appendix 11 Luxury flame retardant fabrics
Table A11.3 OSU heat release results according to FAA specifications2 Sample
Mass, g
Mohair (61 %)– silk (39 % as warp): plain weave MS1 (ave. of warp and weft) MS2 MS3 MS4 MS5 Mohair (61 %)– silk (39 % as warp): fleur-delis motif MSF1 MSF2 MSF3 Mohair–polyester (warp) MP1 MP2 MP3 MP4 Mohair–cotton (warp) MC1 Alpaca (60 %)– silk (40 % as warp) AS1 AS2 Schneller S-SSCP Airbus board
Thickness, mm
Peak heat release rate, kW m-2
2 minute average HRR, kW m-2 min-1
Time to PHR, s
Pass/fail
5
0.5
34
18
13
Pass
5 — 32 58.5
0.5 — 4.2 8.7
38 86 75 58
16 55 55 41
11 23 21 39
Pass Fail Fail Pass
5 5 —
0.5 0.5 —
55 61 58
27 93 52
14 14 23
Pass Fail Pass
6 32 32 34
0.25 3 4 3
58 67 61 64
35 65 63 46
17 20 18 19
Pass Fail Pass Pass
10
0.5
88
46
23
Fail
8 34 26 —
0.5 5 3 7.2
85 77 55 21
38 60 41 17
19 25 — —
Fail Fail Pass Pass
In summary, the most robust passes cannot easily be predicted in terms of whether additional flame retardant to the supporting board should be present or not. However, the inclusion of aluminium foil (MP4) and use of a thicker board (MS5) does seem to produce consistently lower PHR and average HR values.
Smoke and toxic gas analyses The smoke and toxic gas emission levels are listed in Table A11.4 for a selection of the samples in Table A11.3. Results were undertaken for flaming and non-flaming conditions. It would appear that all samples except one (MP3) tested under both
Appendix 11 Luxury flame retardant fabrics
241
Table A11.4 Smoke and toxic gas emissions of selected samples Sample
Smoke: DS within 4 min
HCN, ppm
CO, ppm
NOx, ppm
SO2, ppm
HCl, ppm
HF, ppm
HBr, ppm
Pass/ fail
Test criteria Mohair (61 %)– silk (39 % as warp): plain weave MS1 (ave. of warp and weft); flaming MS1 (ave. of warp and weft); non-flaming Mohair–polyester (warp) MP3 Flaming MP3 Non-flaming Mohair–cotton (warp) MC1 (ave. warp and weft); flaming MC1 (ave. warp and weft); nonflaming Alpaca (60 %)– silk (40 % as warp) AS1 (ave. warp and weft direction); flaming AS1 (ave. warp and weft direction); non-flaming
<200
<150
<350
<100
<100
<150
<100
—
Pass
94
10
100
—
3
8
—
10
Pass
54
10
10
—
5
8
—
5
Pass
210 117
5 5
10 10
5 4
56 38
7 5
23 9
Fail Pass
153
20
175
—
10
15
2
15
Pass
70
5
50
—
13
15
3
5
Pass
141
20
125
—
11
14
1
18
Pass
73
18
13
—
14
10
1
6
Pass
3 4
Notes: DS is the optical density of smoke after 4 minutes exposure to the incident heat flux.
conditions have produced passes under the FAA and related regulations.2 The upper limits for each emitted species are listed also in Table A11.3. Furthermore, the emission values for flaming conditions are in all cases greater than respective non-flaming conditions. This reflects upon the effectiveness of the inherent flame retardance of the component fibres and the flame retardant finishes present. Single-layered fabric samples show some variations which might be both warp (mohair versus alpaca) and weft (silk versus cotton) related. For example the presence of the cotton weft in MC1 fabrics increases the smoke and CO emissions relative to the silk weft in MS1 fabrics under both flaming and non-flaming conditions. Alpaca as a weft (AS1) also appears to have slightly increased smoke and CO
242
Appendix 11 Luxury flame retardant fabrics
generation compared to mohair weft in MS1 when both contain silk warps. The effect of polyester warp in MS3 samples is masked by the adhesion of this sample to the S-SSCP board. All samples showed measurable amounts of sulphur dioxide from the mohair or alpaca fibres present (see Table A11.1) as well as hydrogen chloride and hydrogen bromide, probably from the flame retardant back-coating applied to each fabric. Again, flaming values are greater than respective non-flaming values and this probably is a consequence of the antimony–halogen flame retardant formulations acting specifically in the flame and so generating higher concentrations during flaming combustion conditions.
Conclusions It is evident from these results that fabrics and fabric panel composites in which the weft yarns are mohair and alpaca can be fabricated in a manner which enables the strict fire and emission performance requirements of FAA specification JAR 25.853, Part IV, Appendix F to be met. Not only are the fabrics of extremely high visual and physical character and hence luxurious aesthetics, but also fabric weights are considerably less than currently available fabrics used in aircraft interiors. Based on the current degree of success, it is intended to develop a range of fabric designs and structures which will guarantee FAA specification passes. This will entail studying the effect of fabric composite design variables on heat release properties in the first instance followed by the creation of a multi-dimensional model which will enable fabric fire performance to be predicted at the design stage.
Acknowledgements This paper is published by kind permission of Interscience Communications, London, from the proceedings of Fire and Materials, 2001, San Francisco, 2001. The authors wish to acknowledge BAE Systems, UK and Hexcel Composites, UK for the use of their respective OSU calorimeters and to the Department of Trade and Industry, UK for financial support for this work.
References 1 Allied Signal Aerospace News Release, 10 October 1998, Allied Signal Corp., CA, USA. 2 FAA specification, FAR 25.853, Part IV, Appendix F. 3 ASTM E-906-99, ‘Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products’, American Society for Testing and Materials, 1999. 4 ASTM E662-97, ‘Standard Test Method for Specific Optical Density of Smoke Generated by Solid Materials’, American Society for Testing and Materials, 1999. 5 Benisek L, in Flame Retardant Polymeric Materials, Vol. 1. Ed. M Lewin et al., New York, Wiley Interscience, 1975, 137. 6 Hunter L , Mohair: A Review of its Properties, Processing and Applications, NMB Printers, Port Elizabeth, S Africa, 1993.
Index
Accessories, fashion, 40 Aeronautics, 235 Afghanistan, 136, 137, 140, 143, 227, 229 Alexandria, 4 Almeria, 4 Alpaca, 92, 173, 236, 239, 241 Altiplano, 147, 156 American Assoc. of Textile Chemists and Colorists, 227 Ankara, 73, 74 Antheraea, 23 Arab conquest, 4 Arabia, 3 Arabs, 5 Argentina, 68, 113, 151, 156 Aromatic polyamide fibres, 235 Artificial silk, 11 Asia Minor, 4 Asia, 3 Aspartic acid, 195 Astrakhan rugs, 72 Australia, 68, 74, 112, 136, 137, 140, 144, 151, 227 Avignon, 6 Belon, 74 Bactrian Camel, 74, 133, 143 Bi/multivoltine hybrids, 49 Bible, 73 Birth coat, 88 Bivoltine silkworms, 19, 53 Bolivia, 151, 154, 156 Bologna, 5 Bombyx mori: bleaching, 33 Bombyx mori, 3, 10, 12, 13, 49, 53 Brazil, 35, 44, 45, 47, 50, 52, 56 Burn-out fabrics, 31 Britain, 74 Brunnat, Paul, 51 Bulgaria, 42 Bursa, 7 Byzantium, 5
Camel hair, 75, 92, 143 Camelid fibres, 133 Canada, 170 Carcinogenic dyestuffs, 34 Carding, 134 Carpets, 70 Carrhae, 3 Cashgora, 71, 92, 142, 227, 228, 229 Cashmere and Camel Hair Institute (CCMI), 139, 142, 228 Cashmere Foreign Trade Centre, 140 Cashmere, 92 Cashmere Fibre, 71, 227, 228 Cashmere Goat, 73 Catherine the Great, 8 Centexbel, 136 Central African Republic, 59 Chaku, 152 Changeant, 31 Charka, 21 Charles Martell, 5 Charles V, Holy Roman Emperor, 74 Charles VII, 6 Chemical Fibres, 11 Chile, 156 China Commodities Inspection Bureau (CCIB), 26 China National Silk Import and Export Corp., 49 China, 5, 37, 43, 44, 45, 46, 47, 48, 50, 55, 58, 60, 136, 139, 140, 141, 143, 144, 151, 163, 167, 220, 227, 229 China Dehairing machinery, 134 Production, 58 Chinese National Standard, 227 Chromium, 34 Classification, 24, 158 Clipper ships, 9 Coca, 56 Cocoons, 2, 10, 11, 14, 16, 19, 21 Columbia, 58, 151
243
244
Index
COMEX (External Peruvian Commerce), 151 Confucius, 2 Consumer education, 66 Cooking, 20 Cordoba, 4 Corporations, 6 Cortex, 82, 191, 194, 213 Cotton, 109, 239, 241 Crêpe de chine, 31 Crêpe fabrics, 31 Crêpe yarns, 29 Cria, 149 Crimp, 201 Croisure, 21 Crossbred-cashmere, 229 Crusaders, 5 Curtains, 70 Cuticle, 79, 191 Cystine, 194 Dalton Lucerne Rare Fibres UK Ltd, 234, 235 Damascus, 4 Damask, 4 Dawson International, 140, 220, 221, 224 Dawson, Joseph, 140, 227 Dehairing, 134, 139, 140, 146, 154, 158, 173, 227 Denier, 21 Design, 3, 4, 5, 6, 7, 8, 39, 57, 65 Ethnic, 50, 59 Jacquard, 8 Diamond fibre (the), 72 Diwali, 50 DNA (deoxyribo nucleic acid) sequences, 87 Domestication, 2 Douppion, 23, 40 Draw-boy, 8 Draw-loom, 7 DREF spinning, 206 Dromedary, 133, 135 Dunnick, R, 154 Duplan tester, 25 Dyeing, 135 Dyed in the gum, 31 Dyes, natural, 34 Dyeing yarn, 29 Dyeing piece, 21 Eastern Cape, 110 Eastern Europe, 163 Edict of Nantes (revocation), 7 Egypt, 4, 59, 73 Embroideries, 6 England, 8, 74 Enzyme, 38 de-gumming, 33 Epidermis, 82
Europe, 3, 4, 5, 45, 52, 59 European Union, 52, 59 Exodus (the), 73 Fashion, 68, 107, 166 ‘Grunge’, 45 FAST system, 210 Felting, 79 Fibre adulteration, 229 Fibre identification, 83, 135, 229, 230 Fibrils, fibrillation, 36, 38 Fib, 10, 16 Finishing, 135 Flammability, 71, 109, 151, 234, 235 Flax, 2 Flexural rigidity, 208 Florence, 5, 6 Follicles (Mohair), 89, 91 France, 6, 7, 8, 40, 163, 166 Decline of seiculture, 13 Designers, 8 François I, 7 Free trade, 9 Friedlin, René, 143 Furnishing fabrics, 6, 53 Aeroplanes and yachts, 135, 234 Gansu, 144, 167 Gare fibres, 79 Genetic engineering, 61 Genoa, 5, 7 Germany, 8, 9, 50, 151, 163, 227 Glycine, 194 Gobi Desert, 136, 143 Grainage, 14, 19, 41 Great Britain, 9 Greece, 4 Greenland, 170 Grenada, 4 Guanaco, 135, 236 Guilds, 6 Habutae, 28 Hand weaving, 21, 29, 53 Harran, 3 Helices, 191, 192 Henri IV, 7 Hereditability, 88 Heterotype fibres, 79 Himalaya, 23, 73 Himalayas, 73, 166 Holland, 74 Hong Kong, 37, 46 Huacayo, 149 Huarizo, 135, 149 Hubei, 2 Huguenots, 8 IMA Mohairlabs Association, 116
Index Image, 57, 59, 141, 142 Mohair, 113 Incas, 155, 156 India, 3, 23, 44, 46, 49, 60, 163 Handloon weaving, 21 Indonesia, 58 Inner Mongolia, 136, 144 Instars, 14 Insulin, 62 Intellectual property, 6 Interbreeding Camelids, 135 Goats, 135 International Mohair Association, 114 International Silk Association (ISA), 21, 25, 26, 40, 179 International Wool Textile Organisation (IWTO), 94, 229 Inuit, 173 Iran, 55, 136, 137, 140, 144, 227, 229 Italian Art, 5 Italy, 5, 13, 46, 54, 141, 142, 146, 151, 158, 162 Ivory Coast, 59 Jacquard, Joseph-Marie, 8 CAD, 63 Japan, 3, 40, 43, 44, 45, 46, 50, 52, 54, 59, 142, 146, 151, 158, 162 Production, 58 Raw silk testing, 28 Reeling machines, 21 Jiangsu, 43 Justinian, 4 Karakul, 92 Karnataka, 49 Kashmir, 73, 142 Kawabata system, 66, 210, 211, 212 Kcara, 152 Keretia, 82, 109, 139, 195 Kemp, 76, 79 Kenya, 59 Kermel, 235 Khotan, 3 Kimono, 52 Knitting, 30, 63, 106, 166 Knitwear, 141, 146, 151, 154, 170, 173, 220, 227 Korea, South, 3, 43, 45, 46, 53, 59 Korea, North, 50 Korea, production, 58 Krefeld, 9 Kurdish Goat, 74 Labelling mohair, 83 Labour saving Feeding, 13 Reeling, 21 Laos, 58 Legislation, 221, 222
245
Mohair, 74 Peru, 156 Protectionist, 57 Legislation/regulation China, 2, 22, 140, 141 European consumer protection, 34 French, 7 Japan, 43 Musk Ox, 170 Peru, 156 Roman, 4 Silk, 33 Turkey, 74 Lepidoptera, 11 Lesotho, 68, 88 Liaoning, 23 Limiting Oxygen Index (LOI), mohair, 109 Lipids, 191 Cell membrane complex, 191 Llama, 92, 135, 152 London, 8, 9 Louis XI, 6 Lustre, 79, 213 Luxury, x Lyon, 6, 7, 8 Piece dyeing, 34 MacArthur, General Douglas, 40 Macclesfield, 9 Macrofibrils, 191, 192 Marseilles, 9 Marco Polo, 5 Means of exchange (silk), 2, 5 Medullae, 76, 79, 81, 83, 135, 163 Melain, 68 Meiji Emperor, 51 Merchants, 25, 146 Methyl methylacrylate, 33 Michigan, 110 Microfibres, 36, 57 Microfibrils, 191, 192 Middle Ages, 5, 73 Middle East, 50 Mislabelling, 229 Misti, 135, 149 Mohair base, 92 Mohair Council of America, 110 Mohair Mark, 83, 115 Mohair Trust, 110 Mohair, 228, 236, 239, 241 Style Character, 98, 99 Classing, 111, 112 Grading, 100, 111 Sorting, 102 Mohairlabs, 95, 116 Mongolia, 136, 137, 139, 141, 143, 144, 146, 227 Mongols, 5
246
Index
Morus alba, 13 Mother hair, 88 Mukhayar, 73 Mulberry leaves, 13 Mulberry leaves, replacement, 13, 52, 61 Mulberry tree, 13, 41, 45 Multivoltine silkworms, 19, 20, 49, 53 Murcia, 4 Myanmar, 58 Natural dyes, 34 Near Infrared Spectroscopy (NIRS), 95 Netherlands, 8 New Mexico, 110 New Zealand, 68, 112, 136, 137, 140, 144, 227 Nîmes, 7 Ningzia, 144 Nomex, 235 North Africa, 4 Nylon, 165 Oak trees, 23 Oklahoma, 110 Olivier de Serres, 7 Optical Fibre Diameter Analyser (OFDA), 87 Organzine yarns, 29 Ottoman Empire, 7 Paraguay, 58 Pasteur, Louis, 8 Paterson, New Jersey, 9 Pebrine, 8, 19 Persia, 4 Persians, 5 Peru, 147, 151, 156, 159 Pesticides, 117 Pheromones, 17 Philippe de la Salle, 8 Phrygia, 73 Pollution, 44 Polyester fibres, 59, 152, 235, 239 Polyvoltine, 53 Portugal, 13 Price/fibre characteristics relationship Mohair, 94, 99 Cashmere, 229 Protestants, 8 Protofibrils, 191 Puno, 148 Purging, 24 Qinhai, 167 Quviut (Quiviuk), 173 Rayon, 11 Repco spinning, 205 Ring shawls, 220 Roman Empire, 3 Russia, 144
Satin, 30, 31 Scanning electron microscope (SEM), 84 Schappe, 24 Scotland, 141, 220 Scroop, 35 Sea Island cotton, 135 Seam-pucker, 210 Serge, 31 Sericin, 4, 9, 10, 16, 20, 21, 31, 33 Sericulture, 4, 7, 13, 40, 51, 52 Decline, 13, 14, 42, 43, 45, 53, 58 Serine, 10, 195 Seriplane, 25 Serrel, Edward, 51 Sers, 4 Shanghai United Wooltex Corp Ltd., 223 Shanghai, 43 Sichuan, 43, 167 Sicily, 5 Silicone, 35 Silk, 142, 235, 239, 241 All silk, 33 Blends, 24, 63 Carpets, 55 Chrysalis, 16 Image, 57, 59 Ink-jet printing, 63 Knitted, 30, 63 Larva, 16 Lingerie, 40 Means of exchange, 2, 5 Moth, 17 Noil, 24 Printing, Korea, 54 Prints, 57 Production development projects, 58 Pupa for food, cosmetics, beverages, 54 Pure silk, 33 Research, 51, 60, 61 Road, 3, 5 Sand-washed, 37, 59 Shot, 31 Spun, 24, 50, 55 Stockings, 51 Thai, 21 Thai, white, 53 Thai, yellow, 53 Trade, 3, 4, 5, 6, 9, 28, 44, 46, 53 Waste, 20, 21, 24, 50, 55 Silkworm Eggs, 4, 13, 17 Genome, 20 Rearing, 11 Transgenesis, 62 South Africa, 68, 74, 88, 109 South African Mohair Growers Association, 110 South African Wool Textile Research Institute (SAWTRI), 102, 198, 204, 205
Index South America, 163 Spain, 4, 13, 151 Spinning, 134 Spitalfields, 8 Stannic acid, 33 Stiffness, 208 Stifling, 17 Suez Canal, 9 Suint, 91 Suri, 149 Switzerland, 8 Syria, 4 Synthetic fibres, 109 Tabby, 30 Taffeta, 30 Texas, 68, 110 Texas A&M Centre, 111 Textile cycle, 47 Thailand, 21, 53, 59 Threonine, 195 Tibet, 73, 136, 143 Tierra del Fuego, 159 Tin salts, 33 Tomioka, 51 Tournefort, 74 Tours, 6 Tram yarns, 28 Tui, 149 Turkestan, 74 Turkey, 42, 68, 73, 74, 88, 111 Turquet, Etienne, 6 Twill, 30 Tyrosine, 194, 195 Ultraviolet light, 11 United Kingdom, 50, 113, 146, 151, 158, 162 United States, 37, 46, 50, 51, 54, 55, 65, 68, 74, 88, 110, 142, 146, 151, 158 Federal Aviation authority, 234, 235 Upholstery fabrics, 70
247
Uptwisting, 28 Uzbekistan, 55 Valencia, 4 Velvet, 6, 31 Venice, 5, 6 Vestments, 6 Vicuña, 236 Vietnam, 50, 54 Viscose, 31 Wax, 91, 922 Weighting, 33 Western Europe, 142, 146, 151 Wigmakers, 74 Wild silk India, China, Vietnam, 23 Tasar, muga, eri, 23 Wool, 2, 34, 59, 75, 77, 92, 107, 108, 135, 165, 191 Flame retardant, 235 Lustre Merino, 77, 86 Lustre, 75 Merino, 141 World Trade Organisation (WTO), 64 World Trade Organisation Agreement on Textiles and Clothing (ATC), 64 World Trade Organisation General Agreement on Tariffs and Trade (GATT), 64 World Trade Organisation Multi-Fibre Arrangement (MFA), 64 Xi’an, 3 Xinjiang, 144 Yak hair, 92 Zambia, 59 Zhejiang, 43 Zimbabwe, 59 Zurich, 9
