ties of rayon with the wet strength and wear life of cotton. They are wrinkle resistant, shrinkage controlled, completely washable, and quick drying. The dyeing properties are excellent and give an almost limitless range of fast colors for fashion needs. I n blends and combinations the two fibers yield a wide variety of fabrics. They may be made in light constructions suitable for dress goodsor shirtings,in suiting fabrics, or in constructions for sports and work clothes. Made of the two lower-priced textile fibers, these fabrics approach very closely the manufacturer’s conception of an ideal fabric. A parallel which the author regards as valid from every standpoint is that the work that is now being done in textiles parallels with remarkable similarity that which has been done in the last 30 years in metallurgy. The great advances in metallurgy during that period have been largely due to the vast array of alloys v i t h
which American engineers are today performing such great miracles. The blends of the many textile fibers, to which further desirable properties may be given by chemistry, are comparable in every way to those alloys. I n both industries the production engineers are hard put to keep up with the chemists. LITERATURE CITED
(1) Horne, M. K., “The Competitive Position of Cotton,” p. 262, Washington, D. C., National Cotton Council of America,
July 1947. ( 2 ) Smith, Leonard, Textile Age, 16, 61 (1952). ( 3 ) Textile Organon, 23 (January and February 1952). (4)Ibid., p. 49 (February 1952). (6)Ihid., p. 76 (March 1952). RECEIVED for review March, 31, 1952.
ACCEPTEDJuly 7, 1952.
Silk WILLIAM S. KILBORNE William Skinner & Sons, F o u r t h Ave. and 1 7 t h S t . , Netu Y o r k 4 , .V. Y . i
”i*
AST month we read with he relative position of silk in the textile industry has So high was the iegard of suffered a continuous decline since 1929. In 1951 only a great deal of interest the peoples of the world for silk that it became part of the the story of Elizabeth, 5% as much silk was brought into this country as was language. I n English we find received in 1929. Silk, however, does have a combination the new Queen of England. expressions such as ‘(fine as of desirable assets that is not found in any of the synTwo hundred years ago monsilk,” “Smooth as silk,” thetics. I t shares with nylon the honor of being the archies were the most prev“hair like silk,” “silken comtoughest of fibers, and its resilience is the envy of all the alent form of government. plexion,” and so forth. other fibers. It is warm in w-inter, cool in summer, and Since then we have seen them Although silk of the finest has a high resistance to twisting forces. With scientific overthrown in most of the quality can be grown in any cooperation and study, most of the problems connected countries of the world. Some with silk could be eliminated, and the future for silk temperate climate, it has countries, like the United would be much brighter. been successful only in those States, developed better areas where labor has been forms of government, and cheap. This is due t o the some tried d i e t a t o r s h i p s , fact that no machine has ever which proved to be might17 been discovered to reel the poor substitutes. Others, silk strands from the cocoons that was efficient enough to replace like England, took away almost all the power from their monlow cost labor. archs, but kept the ruling families in existence as a symbol. Instead, modern man invented “artificial silk” which became a Thus we find that where there are monarchs today, they are commercial product in the 1920’s. Improvement in the qualities generally revered and respected, and the people are willing to of viscose, acetate, and cuprammonium yarns conspired with the pay extra taxes to maintain the luxury of having a royal family. depression of the 30’s t o end the reign of the silk queen. Rayon In the textile world the queen oi fibers is in much the same also was largely responsible for having the industry turn to position. Silk has largely been replaced by substitutes-some planned advertising and merchandising. It seized on the innate better than the original for some purposes and some not so good. desire in our people to have something new and glamorous a t a And as in the mid-twentieth century monarchies, there are still reasonable price. many people \Tho are willing to pav extra tariffs to have fabrics Of course the rapid growth of the rayon industry is well k n o m made of the queen of all fibers-silk, But what d o we know of but a few statistics will illustrate the decline of silk. In 1929, this amazing queen who has reigned for over 4000 years? 662,000 bales were imported into this country of which 59% was Credit for the origin and development of silk goes to the Chinese for the weaving industry. In 1939 this figure had fallen t o Empress Hsi Ling Shi in about 2640 B.C. It is recorded that 388,000 bales and only 8.9y0 of this went to the weaving inshe devoted herself personally t o the care of the silkworms. dustry. I n August of 1941 the government froze the silk in this With this beginning, silk remained a virtual monopoly of China country, and thus none vias produced for any civilian consumption for something like 3000 years. Then some refugees traveled to until after the war. Korea and set up the industry there. The story is told that a During this war period another man-made fiber, nylon, came secret mission from Japan to Korea in the third century sucinto its own, It proved its worth in replacing silk in parachutes. ceeded in capturing four girl silkworkers and a supply of silkworm When the war ended nylon hose were here to stay in spite of the eggs. availability of silk. The real decline of silk is proved by the fact Sericulture then spread westward from China, and silkworms that in 1951 only 36,000 bales of raw silk were imported in this finally became a commodity raised to a greater or lesser extent country for all purposes. in all countries of Europe, and on to the colony of Virginia in 1622.
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SYNTHETIC FIBER Stated another way, 1927 was the last year in which the Census of Manufactures listed a silk weaving industry. At that time there were 1648 plants employing 128,000 wage earners. Many went out of business and some, like William Skinner & Sons, turned t o the weaving of synthetic yarns. Rayon had specific advantages for the weaver. First and perhaps most important was its stability in price. Secondly, it was easy to secure. The old “silk express” rushing its valuable cargo from Seattle and San Francisco to New York t o cut down on interest charges was no longer necessary. Thirdly, being mechanically made, its quality was uniform, and lastly, it would run on looms that were much cheaper to operate. Here was a product cheaper for the weavers and knitters in the raw, cheaper to weave, and marketable on a sound mass basis. The old silk manufacturers were forced t o revamp their thinking from a larger profit per yard t o profit based on volume. Showing the present status of silk another way, the Department of Commerce in their Facts for Industry points out that a year ago 4000 looms were operating on silk, 7000 on nylon, and 100,000 on rayon. On a competitive basis, therefore, queen silk has already been relegated to the position of a luxury-something desired but not necessarily needed. Silk production facilities in Japan were decimated during World War 11-for example, in 1951 only 215,000 bales were produced for the whole world. In another 5 years the Japanese hope t o increase this production to 300,000 bales. If the newly created price stabilization plan in Japan is effective and if the demand for silk as a fashion fabric continues to grow, it may return to eminence, if not, t o the power of yesteryear. Conceding, nevertheless, that silk has already succumbed to the competition of rayon and nylon, what of Orlon, dynel, Dacron, Acrilan, and others? PROPERTIES OF SILK
Silk is a strong fiber. It has a tensile strength of 64,000 pounds per square inch. In comparing this with other yarns, only five are stronger: glass, flax, Fortisan, asbestos, and nylon in that order, Weaker than silk are Tenasco rayon, cobton, steel wire, viscose rayon, vulcaniqed rubber, acetate, and wool. Silk shares with nylon the honor of being the toughest of fibers. In fact, these two fibers are more than twice as strong as their nearest competitor. By toughness is meant the amount of energy which must be expended per unit mass of the material t o rupture the fiber. Silk has this great toughness because it combines with its strength a high degree of elasticity, though not as much as nylon. A silk fiber can be extended between 20 and 25% of its length before it breaks. One area in which silk is actually way ahead of nylon is in what is known as the modulus of rigidity. This means its resistance t o shearing or twisting forces. Here only glass and kapok rate above it, whereas below it in order are cotton, dynel, flax casein, fortisan, viscose, wool, saran, acetate, and nylon. In resilience, silk is the envy of all the other fibers. It shapes well and after certain finishes are applied has a natural crease resistance. Perhaps even more important are its advantages over manmade filament fibers as conductors. Silk feels warm next t o the skin in winter, and yet being a poor heat conductor, it is cool to the skin in summer. I t might also be added that silk suffers a gradual degradation when exposed to intense sunlight and has a tendency to yellow with age. It is difficult t o obtain colors that are fast to both light and washing, although some progress has been made in this direction. The bright colors that are traditionally associated with silk are by all odds the poorest in color fastness. The grading of raw silk is done by hand, with the obvious result that there are some irregularities in the yarn. This never September 1952
it is not herm-; possible t o tell when buying silk whether or not it will be “lousy” when boiled off. The term “lousy silk” refers t o a hairy condition that may appear after the woven piece goods are finished. Such conditions make it necessary to re-educate manufacturers of garments and consumers t o the fact that they cannot expect uniform appearance in a piece of silk. This, of course, is one of the beauties of real silk. Of the newer man-made fibers, Vicara and Acrilan are available a t present only in staple form. The production of filamenti dynel is still extremely limited. These newer fibers will compete strenuously with woolen fibers, but will compete with silk only in the general field of men’s suitings. This is a new field for silk, and it is amazing how rapidly it has developed in the last 2 years. Silk suits are cool, light in weight, and readily lose their wrinkles. These are the characteristics the newer synthetics are trying t o out-do. A Dacron suit, hosed down with water, will retain ita shape perfectly, will not wrinkle, and will even retain the crease in the trousers. A worsted suit will not fare so well, and this would also be harsh treatment for a silk suit. Orlon and Dacron are available in either filament or staple form. In continuous filament both have been made into fabrics that feel amazingly like silk. Whether they will be able t o move into the limited luxury field occupied by silk today is highly doubtful. Of course, these fibers, in addition t o their own individual characteristics, have the distinct advantage of being developed by a single corporation whose scientists not only will constantly be improving them but also whose advertising and merchandising departments know how t o build and fulfill a consumer demand. Silk, on the other hand, has many small concerns handling every phase of its development. I n Japan today there are many egg dealers, many farmers, many filatures, and many exporters. Here we have many importers, throwsters, weavers, dyers, and importers of fabrics. These are held together by the International Silk Association, but an association inevitably cannot be as effective RS a single corporation. The association is working on all phases of the problem of restoring silk to a greater position of eminence and with technical help believes it is decidedly possible. PROBLEMS IN SILK PRODUCTION
As the raising of silk has not been economical in this country, it has received little attention. However, M. Hanaoka, the president of the Katakura Industry Co., which produces almost 20% of the silk in Japan, recently announced that his company had developed a reeling machine which will cut processing costs 30% and produce four to five times as much silk as the old method. This machine is in operation in two of their 33 filatures at the present time. If reeling the silk from cocoons can become a mechanical operation, there could be a new industry, adaptable t o this country, but it needs the help of technologists. The Japanese have also been working on scientific breeding which will produce silkworms that will spin stronger and more even fibers. I n this regard Hanaoka said t h a t through selected breeding over a period of years, his company has perfected a high tenacity fiber. H e believes it will equal and hopes it will better nylon. If this is so, one of the practical advantages of nylon in hosiery will be eliminated. Furthermore, work is now being conducted with the aim of producing silk adaptable for the high speed weaving used in this country. Therefore, a large field has been opened for basic research on the yarn itself-in breeding for average thickness, uniformity, and strength as well as in reeling. Another approach t o the problem of silk production is the shortcut method of raising silkworms with a large fiber “gut” which could be dissolved chemically and spun mechanically through a spinnerette, the same as is used with man-made fibers. Japan, Switzerland, and England are all giving thjs approach some thought. If the problem could be worked out in the United
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States, not only would the detriment of unevenness in silk be solved, but a whole new farming industry could be started here. The International Silk Association in Paris is working on the most urgent problems at the moment and would welcome any help that science could provide. For example, there is the problem of degradation in grand Teint dyeing. No matter x h a t precaut,ions are taken in the vat dyeing of silk the strength is always ter or lesser degree. The deeper t,he colors, the greater the problem because of the high proportions of dye in the liquor. As mentioned before, it would be extremely helpful if a manufacturer when purchasing Bilk could ascertain whether or not it is lousy. This condition is latent and is first evident when the silk is boiled off. It is apt to be further aggravated in dyeing, particularly if fast dyes are used. Some microscopic and tinctorial methods have been developed, but none is truly reliable. Another problem the association is working on is the degradation of silk by light. Special treatments have been developed to slow down this degradation, but development of more efficient and permanent methods would be desirable. There is a great demand today for fabrics containing ”ecroop.” Of all t’he fibers known today, silk has the most scroop. This is the word used to describe the rustle that is associat,ed viith silk taffeta dresses. In order t o build up scroop, strong acids are used in the finishing of the fabrics, and although standards for the strength of these acid baths have been set up, the finishers may a t times exceed the standards. To date there has been no test developed to show whether or not these standards have been exceeded. It is therefore impossible t o knoxv where the responsibility lies when a fabric with scroop goes tender. Everyone in the industry agrees that fabrics and colors that are truly mmhable would be a great boon to silk. By truly washable I mean thnse that could withstand the treatment of a washing machine. Publicity has been given some silk fabrics with notice that the goal of washability has been achieved. But it is not yet possible in the vivid colors normally associated with silk. Since a start has been made, however, it should not take long to make this a reality for all silks. If scicntkts could fmd the answers to even some of t,hese problems, the demand for silk would be increased manyfold. In spite of t,he fact that the market for silk has been drastically cut, the people of America still love it,. They are proud of every silk article they possess. Only a few weeks age wc received a letter from a girl who enclosed a clipping of one of our old silk satins with the Skinner name woven in the selvage. The fabric had been purchased by her grandmother for an evening wrap; this was given to the girl’s mother, who gave it t o her. The granddaughter had cut it down and made a bed-jacket of it and then recently had cut it further to make a robe for her child. One cut of goods thus served four generations. This type of letter is is not unusual in our business. The record of silk in the pasb and the romance rassociated with it are maintaining today’s market. CURRENT MARKETS FOR SILK
Today’s marketa for silk are still found in a wide variety of fields: Women’s wear, men’s wear, home furnishings, sewing threads, and some industrial uses. The current fashion trend, demanding stiffer, thicker fabrics, has given yam dyed silks quite a boost, and silks arc being used in formal evening gowns, dinner and cocktail dresses, and evening coats. Even today, a bride can choose nothing finer t o be married in than a silk satin gown. Silk shoe satin is still used for the best evening slippers. Piece-dyed and printed silks continue in demand for lingerie, blouses, dresses, negligees, and scarveE.
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Silk is still the fiber most prcferred by the world’s foremost designers, and it is still sold in the most luxurious shops. revel.theless, nylon tricot has played havoc with silk in the lingerie field. The tricot construction has done much to eliminate the clammy feeling of nylon next to the skin. In addition, the innate strength and quick-drying properties of tricot make it so desirable that today silk lingerie is a gift item for those u-ho can afford to give luxuries. Because of the versatility and rapidity of change in fashions the newer filament fibers represent potential competit,ion for silk in the women’s market, particularly when practicality can h e combined with fashion. Silk in hosiery is a thing of the past, except for those few women who are allergic t o nylon. Of course, if stronger silk yarns are developed, a market for silk hosiery might, return because silk is so much warmer than nylon. For decorative purposes, the finest laces are still made of silk. In the men’s wear trade, silk is in grcatest demand for ncckwear; the best ties are still made of silk. Here its resiliencc particularly is used to good advantage. The resilience of Orlon might become a threat t o silk in this field when Orlon is produced in finer deniers and can be well printed. If Dacron could be printed, it also would be competitive. Although scarves are not as fashionable as they once were, the warmth and lightness of silk make it ideal for the best scarves. Silk is the only fiber today that, is used in the facing of a tuxedo. It may be that it will be displaced when the newer synthetics replace wool in dinner cloths. Beautiful facings can he made of nylon but they will ,not lie flat on the existing tuxedo cloths. Silk and wool, both being animal fibers, shrink and strctch together thereby allowing the facing t o lie flat. Silk damasks and velvets produce the most luxurious draperies for home furnishings: they are used also for church decorations. Man-made fibers today are so satisfactory, however, that only a few people are willing to pay for the luxury of silk. Most of the bolting cloth used in filtering today is made of silk. It is not an easy clot,h t o ivcave and comes mainly from Sn.itzerland where it has been made of eilk for many generations. Bccause of the superior strength of nylon it is possible that it would make a better bolting cloth. In the manufacture of cartridge bags, silk is still the h r d fiber to use because it leaves 110 glowing spark. I t is belicvccl that a substitute will be developed for this purpose within the ncxt year. I n surgical sutures also, silk is giving way rapidly t,o nyloli. For many years silk was blended with wool for use in hosieiy and underwear to give better wearing qualities. There is reason to believe that experiinentation and research in blending silk with the new synthetic fibers that have wool-like characteristics would result in improved fabric appearance and better wearing qualities. The uses for silk are extremely diversified. In many ol its applications it has already handed over the position of leadcrship to viscose, acetate, cuprammonium, and nylon yarns. In other uses, foreign countries have captured our own doniest,ic silk market. I n 1951, over 29,000,000 yards representing almost 2,000,000 pounds of woven silk were imported into this country. This represents a rate of consunipt.ion 50% greater than our production. For all practical purposes silk has already lost a battle to the man-made fibere. New fabrics of Dacron and Orlon are amazingly silky. However, these newer man-made fibers will probably take on wools as their main protagonist. So that I will not be closing on a pessimistic or negative note, I hope that some of you gentlemen may offer your scientific hand to the lady-to queen silk-and if you do, I’m sure she can look to the future nith hope and confidence. RECEIVED for review hIarch 31, 1982.
INDUSTRIAL AND ENGINEERING CHEMISTRY
A C C E P T ~June D 10, 1962
Vol. 44, No. 9
