PART THREE

SILK

By BENJAMIN STRONG, JR. of the INTERNATIONAL ACCEPTANCE BANK, INC.

Photographs by courtesy of William Skinner & Sons and the Keystone View Co.

[Illustration: _Picking Mulberry Leaves_]

## CHAPTER I

THE RAW MATERIAL

1. HISTORY

[Sidenote: _Early Sericulture_]

Silk owes its position as one of the three leading textiles to its qualities of strength, elasticity and beauty—in which respects it surpasses all other fabrics. Its production dates far into antiquity; for centuries China was the seat of the industry, guarding the secret methods and processes with the utmost care. During the sixth and seventh centuries A. D. the secret began to leak out and sericulture gradually found root in the Near East and the Levant, whence it spread to Greece, Italy, France and Spain. Japan also took it up and developed it to a very high point.

[Sidenote: _Industry in America_]

Attempts to establish the industry in America have been generally unsuccessful, high costs precluding the possibility of competing with foreign conditions. In addition, the raising of raw silk has been built up principally in countries where there is a system of home industry—a social and industrial system never developed in the United States. However, although America has never been a factor in the producing of the raw material, it has risen to a place of utmost importance in the manufacture of the finished textile. Immense quantities of raw silk are imported from abroad—principally Japan, Italy, and China—and its conversion into the finished products constitutes a most important part of our industry.

2. THE SILK WORM

[Sidenote: _Names and Types of Silk Worms_]

The textile fibre known as silk is a filament secreted by one of two general types of moth larvæ—the cultivated and the wild. The largest proportion is, of course, made up of the former, produced by the worm known as the _Bombyx mori_, while the most common type of wild silk worm is called the Tussah. The name _Bombyx mori_ comes from the name of the family to which the silk worm belongs: the _Bombycidoe_ (spinners), and _mori_, from the _morus multicaulis_ or mulberry tree, on the leaves of which it feeds. The species _Sericaria mori_, or silk worm of the mulberry, belongs to the generic class of _Lepidoptera_ or scaly-winged insects.

[Sidenote: _Bombyx Mori_]

The _Bombyx mori_, with which we are chiefly concerned, is divided into other groups according to the cycle of reproduction. The annuals reproduce once a year, and sixty per cent of the silk worms belong to this class. The bivoltines reproduce twice a year, and the polyvoltines, several times during the year, the first crop being the best.

[Illustration: _Full Grown Worms_]

The study and development of the various phases through which the silk worm passes, leading up to its production of the actual filament, have been a subject of intense research in many parts of the world for a great number of centuries. The present silk worm is nothing more than a highly specialized product of a long train of artificial cultivation.

[Sidenote: _Stages of Growth_]

The cultivated silk worm passes through four changes in its life of two months, i.e., egg, larva, chrysalis (or pupa), and adult—a cream-white moth which is about one inch in length. The moths live only a few days, during which mating takes place, and the female lays several hundred eggs; after about six months these eggs hatch into worms. The latter pass through what are known as four “molts,” or shedding of the skin, before the worm matures, spins its cocoon, becomes a chrysalis, and finally emerges as a moth. This, very briefly, is the life history of the silk worm.

3. MODERN SERICULTURE

[Sidenote: _Countries Producing Raw Silk_]

Silk raising, or sericulture, has been a leading industry in Japan and China for a great many years, while the Near East and such countries as France and Italy have also played a part in the industry—but to a lesser degree. A great deal of this work,

## particularly in Japan and China, has been carried on as a home

industry, but with the growth of modern business methods more and more of the silk raising has come into the hands of companies operating on a highly scientific basis.

[Illustration: _Cocoonery_]

[Sidenote: _Japanese Supervision_]

After many years of experience and experimentation the breeding and care of the silk worm has been put on a very technical and closely regulated schedule that minimizes the chances of loss by waste or the spread of disease. In Japan the industry has been encouraged and fostered by the Government; a special division of the administration is devoted to its attention, and numerous organizations and associations conduct experimental stations for research and study. In fact since about the middle of the 19th century everything possible has been done to foster this highly profitable branch of the country’s industry.

[Sidenote: _Modern Methods of Cultivation_]

[Sidenote: _Hatching the Eggs_]

The merest outline of the modern methods of cultivation will show how highly they have been developed. To begin with, the eggs are placed on sheets of paper or muslin directly after they are laid. These sheets are hung for a few days in a damp atmosphere, and then placed in cold storage for about six months, the period of cold being advantageous for later hatching, which is done by heat.

[Sidenote: _Growth of the Worms_]

After hatching, the worm sheds its skin four times. The periods between the “molts,” or ages, vary with different silk worms, but the total process takes about a month. Worms of different ages are always kept separate, being held on large cloth trays which are carried in tiers along the walls of the rearing rooms. The cocooneries where best results are obtained are quiet, spacious, well-ventilated rooms where an even temperature can be maintained. Each worm is kept absolutely clean and has plenty of room, as overcrowding brings disease. As a precaution mild fumigation is resorted to from time to time. Heavy odors or smoke of any sort are not allowed, as these are disturbing to the worms.

[Sidenote: _Feeding the Worms_]

[Sidenote: _The Mulberry Tree_]

Nourishment is, of course, a very important item for the growing worms, and the best form of food for the _Bombyx mori_ is the leaf of the white mulberry, which must be young, fresh and dry, but never withered. For this purpose mulberry tree raising has become an important by-industry in itself. Three varieties are found, classified according to the time of budding—early, medium and late. The leaves, therefore, can be found in the correct condition for the various stages in the growth of the worm. The late budding trees are cultivated in more abundance, as the worms are larger at that time and consume more leaves. The soil in which the trees grow is important, as it has been found that one which is rich in certain minerals provides leaves that keep the worms in better physical condition. A cold winter followed by a warm spring develops the leaves well, and the condition of the leaves is one of the most important factors in the whole process.

[Sidenote: _Early Development_]

Careful selection of the eggs is another matter of prime importance. When the leaves are almost ready, the eggs are brought out of cold storage and subjected to heat for about a month before they hatch out. When the worm hatches it is about the diameter of a hair and less than three-fourths of an inch long. It gnaws a hole through the end of the egg from which it issues. Nourishment at first is taken by sucking the sap of the leaves, which are at this stage chopped into fine pieces; later the leaves are consumed without the necessity of their being chopped up.

[Sidenote: _Spinning the Cocoon_]

The development is very rapid, the worms consuming their own weight daily. During this period, as has been stated, they shed their skins four times, and after the fourth molt—about one month after hatching—they have assumed their full size. From then on hunger lessens, restlessness grows, and the lifting of the fore part of the body indicates the desire to climb and spin cocoons. For this purpose brush and twigs are provided in the trays, to which the worms attach themselves and begin the spinning process. The silk thread is expelled in a semi-liquid form from two openings underneath the mouth, hardening as it comes in contact with the air. The first threads issued are coarse and rough, having the necessary strength to serve as supports and guys for the cocoon. Gradually the worm is enclosed in the cocoon after three days of continuous spinning, during one of which it is visible and then slowly disappears, though it can be heard working inside.

[Illustration: _Worms Feeding_]

The worm wastes away as its silk glands are exhausted, and becomes a chrysalis, from which the moth escapes after fifteen to twenty days.

[Illustration: _A Nest of Cocoons_]

[Sidenote: _Cocoons for Breeding_]

Cocoons to be used for silk manufacture must be submitted to heat soon after they are completed, in order to kill the chrysalis and prevent it from forcing its way out, thus breaking the fibres. A certain proportion of the cocoons of each crop, however, is allowed to go through the natural process, for reproductive purposes. There is an active market in these breeding cocoons, particularly in Japan and China, and a large quantity are exported annually to Europe and the Near East.

[Sidenote: _Construction of the Silk Thread_]

The female cocoon is oval and the male cocoon is peanut shaped. The silk itself consists of two parts: fibroin (the silk fibre) and sericin (the gum). The thread is made up of two strands of fibre held together by the gum, and the length of thread in a single cocoon varies from three hundred to fourteen hundred yards. The cocoons are white, yellowish, or greenish, but after the boiling process the color of the _Bombyx mori_ silk is pure white.

[Illustration: _Japanese Cocoon Market_]

[Sidenote: _Tussah and Wild Silk_]

The preceding description is concerned more particularly with the latter type, from which the largest proportion of the world’s silk supply is derived, but in a general way it applies to the other types also. The most important of these are the Tussah silk of India and China and the Japanese wild silk. The products are coarser and harsher than those of the _Bombyx mori_, and the natural color is brown.

[Illustration: _A Japanese Filature_]

## CHAPTER II

REELING

1. HISTORY OF THE FILATURE

[Sidenote: _Early Reeling and Twisting_]

[Sidenote: _Vaucanson’s Filature_]

[Sidenote: _Silk Manufacture in Europe_]

The next step in the production of silk is called reeling, and for this purpose the modern filature has been developed. The actual existence of reeling machines is by no means modern, however, for it is a well-known fact that the Chinese knew how to use raw silk as far back as 5000 years ago. Old prints dating back 3000 years show that the hand “reelers” then in use differed little in principle from the highly developed filatures of today. Although China knew how to reel and twist silk for several thousand years, it was only in the third, fourth, and fifth centuries A. D. that other countries, such as Japan and Eastern Europe, took it up. The first filatures were, of course, extremely simple, operated entirely by hand, and produced a very coarse thread. Although a little progress was made during the Middle Ages, the turning point came in 1750 when Vaucanson, a French engineer, invented the first real filature—which combined several reelers, giving the whole process more speed and turning out a product of considerably better quality. This marked the beginning of Europe’s interest in what had so long been an exclusively Oriental industry, and from then on the French, Italians and Spanish in particular took up the study of sericulture and the reeling and manufacturing process. The result was to put the industry on a scientific basis which it had never reached in the East.

[Illustration: _The Reeling Basins_]

2. PREPARING TO REEL

[Sidenote: “_Stoving_”]

The reeling process is the first step in which machinery plays an important part. When the cocoons are ready they must first be submitted to the “stoving” process, or stifling, in which they are exposed to heat sufficient to kill the chrysalis inside. This is followed by further drying, after which the cocoons are shipped in bags to the filatures and may be kept indefinitely without injuring the filament.

[Sidenote: “_Beating_”]

[Sidenote: _Waste Material_]

As a preliminary to reeling, the cocoons are immersed in boiling water to soften the gum that holds the fibre together. While in the water they are brushed with a coarse brush to remove the heavy outer strands of the cocoon—a process called “beating.” These outer strands are usually too harsh and broken to be reeled, but are afterwards utilized as so-called waste which is used for spun-silk manufacture.[4] This applies also to the innermost layers of the cocoon. About one-half of the thread on a cocoon actually finds its way into thrown silk. The remainder is “waste.” When, by brushing, the true threads are reached it is possible to start reeling, and barring occasional breaks these threads are continuous all the way down to the chrysalis.

[4] See Chapter IV. 2.

3. MODERN REELING METHODS

[Sidenote: _Reeling Basins_]

While being reeled the cocoons are floated in basins of very hot water, each basin feeding a reeling machine. A single cocoon strand is too fine to use commercially, so several are taken at a time, varying from three to seven or eight according to the size of thread desired. The size used in this country most extensively is known as 13/15 deniers and is reeled from six or seven cocoons. During the reeling the water is kept at about 60° C., but if the cocoons are very dry a higher temperature is required. A heavy smoke issues from the basins and not only humidifies the room but also penetrates the silk, rendering it very gummy and hard. This is overcome by the use of steam-heated tubes running over and around the machines.

Each reeling machine and basin is in charge of a girl who is responsible for its operation and for the reeling of thread of correct size. She must keep careful watch that the filament comes off the cocoons steadily and that all breaks are immediately taken care of, exhausted cocoons being replaced by new ones at the proper time. In many filatures each girl is charged with so many cocoons and must turn in a proportionate amount of reeled silk at the end of the day.

[Sidenote: _Twisting_]

[Sidenote: _Human Element_]

The twisting operation is an important part of the reeling process, for the raw silk threads, being composed of parallel cocoon filaments, cohering only by their natural gum, would, unless twisted, mat up and become unworkable. Various methods are used to obtain this torque, the general idea in each case being to run the separate cocoon threads through small rings or eyes and then unite them in one thread large enough to reel. In spite of the many mechanical devices and improvements brought out in the last few years, the success of the reeling operation still is dependent on the reeling girl’s ability and care. It is particularly important that she be able to judge the number of cocoons of a certain size and texture needed to make a thread of the required denier.

[Illustration: _Rereeling Room_]

[Sidenote: _Testing the Skeins_]

[Sidenote: _Color of Raw Silk_]

The raw silk is reeled on travellers in hanks known as skeins and varying from 50 to 100 grams in weight, which are taken off by the reeling girl and the ends of the thread tied up to facilitate the work at the mill. Before leaving the filature it is also subjected to critical tests and examinations for size, winding, cleanliness, irregularities, etc. The color of raw silk as it comes off the cocoon and is reeled into skeins is either white or yellow, though some sorts have a brownish or greenish tinge. Tussah silks have a brownish-yellow color. The coloring matter in the cultivated silks is only in the gum and boils out with it, but the color in the tussah is in the fibre, rendering it very difficult to bleach.

[Illustration: _“Books” of Raw Silk Skeins_]

[Sidenote: _Reeling Wild Silk_]

[Sidenote: _Waste Silk_]

Tussah, or wild silk, is not generally reeled by the wet reel process, as the cocoons are apt to be closed up at each end by gum. In China this gum is softened by burying the cocoons in manure instead of immersing them in hot water. This is known as dry reeling. It very often happens that the tussah cocoons are unfit for reeling, due to being pierced or tangled. Silk from these imperfect cocoons is again classed as “waste,” along with the frisons, or outside and inmost layers of the cultivated cocoons, which, as has been stated, are used to make spun silk. In this country waste silk is often called schappe, although strictly speaking this name should only be applied to waste silk degummed by the French process of fermentation.

[Sidenote: _Baling_]

[Sidenote: _Picul Bale_]

The raw silk, having been reeled and twisted into skeins, is next marked and tied together in bundles of skeins known as “books” each bearing the mark or “chop” of its grade. These are packed in bales for shipment, the weight of the bales varying in different countries. In Japan and China they are called picul bales and weigh 133⅓ pounds. Italian silks, on the other hand, are packed in shipping bales of about 200 pounds.

4. SOURCES OF RAW SILK

Of the countries producing raw silk, Japan and China occupy the leading positions by a large margin, the former contributing roughly one half of the world’s supply, and the latter about one third. Italy ranks a poor third with about one tenth, and France, the Near East, India, Spain and the Balkans contribute the balance.

[Sidenote: _Japan_]

Although the greater part of the raw silk produced in the various countries is exported for manufacture abroad, a certain percentage is retained for home spinning and weaving. It is estimated that about 65 per cent of the Japanese output is exported, approximately 90 per cent. of which goes to the United States.

[Sidenote: _China_]

In China over one half of the output is held for domestic consumption, the remainder being divided about equally between Europe and America.

[Sidenote: _Italy_]

The Italian raw silk—a very high quality product—finds its largest market in France, principally in the city of Lyons, the silk center of Europe.

## CHAPTER III

MARKETING RAW SILK

1. MARKETING METHODS

[Sidenote: _Principal Markets_]

The principal raw silk markets of the world are Yokohama, Lyons, New York, Milan and Canton. Of these, Yokohama is probably the largest and most important, due to the pre-eminent position of Japan in raw silk production.

RAW SILK PRODUCTION, INCLUDING TUSSAH SILK

SEASONS 1917-1918 TO 1922-1923

============================================================== 1922-1923 1921-1922 1920-1921 Crops in Pounds Pounds Pounds Pounds —————————————————————————————————————————————————————————————— Europe 8,841,000 7,628,000 8,058,000 Viz: Italy 8,234,000 7,066,000 7,330,000 France 437,000 430,000 551,000 Austria .... .... .... Spain 170,000 132,000 177,000 —————————————————————————————————————————————————————————————— Levant 1,543,000 1,213,000 1,654,000 —————————————————————————————————————————————————————————————— Asia: Total Quantity Exported[5] 57,439,000 53,941,000 35,138,500 Viz: China, Shanghai [6]8,628,000 [6]6,993,000 [6]6,518,500 China, Canton 7,050,000 5,735,000 4,210,000 Japan, Yokohama 41,541,000 40,982,000 24,300,000 India 220,000 231,000 110,000 —————————————————————————————————————————————————————————————— Total, Pounds 67,823,000 62,782,000 44,850,500 Tussah 2,034,000 1,856,000 1,650,000 —————————————————————————————————————————————————————————————— Grand Total, Pounds 69,857,000 64,638,000 46,500,500 ——————————————————————————————————————————————————————————————

================================================================ 1919-1920 1918-1919 1917-1918 Crops in Pounds Pounds Pounds Pounds ———————————————————————————————————————————————————————————————— Europe 4,927,000 6,978,000 7,154,000 Viz: Italy 4,045,000 5,942,000 6,217,000 France 397,000 540,000 452,000 Austria [7]331,000 [7]331,000 [7]331,000 Spain 154,000 165,000 154,000 ———————————————————————————————————————————————————————————————— Levant [7]2,293,000 [7]2,293,000 [7]2,293,000 ———————————————————————————————————————————————————————————————— Asia: Total Quantity Exported[5] 51,860,000 45,475,000 48,026,000 Viz: China, Shanghai [6]10,225,000 [6]9,209,000 [6]8,563,000 China, Canton 7,093,000 3,704,000 5,170,000 Japan, Yokohama 34,222,000 32,308,000 34,050,000 India 320,000 254,000 243,000 ———————————————————————————————————————————————————————————————— Total, Pounds 59,080,000 54,746,000 54,473,000 Tussah 1,960,000 1,561,000 1,534,000 ———————————————————————————————————————————————————————————————— Grand Total, Pounds 61,040,000 56,307,000 59,007,000 ————————————————————————————————————————————————————————————————

[5] The production of raw silk in China and India is unknown. The Japan crop is approximately 47,000,000 pounds.

[6] Excludes Tussah silk.

[7] In the absence of statistics from Austria and the Levant, 1915 production is used as an estimate.

Courtesy of The Silk Association of America

[Illustration: _Unpacking Bales of Raw Silk_]

[Sidenote: _Yokohama Silk Exchange_]

The Yokohama Raw Silk Exchange operates on a basis similar to that of the various cotton exchanges, and transactions are carried on in “futures” as far ahead as five months. The speculative element is very active and its influence is often felt extensively throughout all phases of the industry. On several occasions it has been necessary to close the exchange to avert real disaster after the quotations have been manipulated to an unbelievable extent. During the last few years the Japanese Government and various silk organizations have, by law and regulation, succeeded in improving this situation to a very great degree, and the benefit has been felt throughout the industry.

[Sidenote: _Conditioned Weight_]

Raw silk is sold by weight—in Yokohama, by net weight, that is, less wrappings, etc. Of recent years in most countries it has been the custom to deal by conditioned weight, and as a result the conditioning process has become an important side line in the industry.

2. CONDITIONING

[Sidenote: _Invoice Weight_]

Conditioning is desirable principally on account of the fact that raw silk absorbs considerable moisture. A careless buyer may find after delivery that he has purchased more water than he has silk. To avoid this possibility, Asiatic and European markets in particular have adopted the conditioned weight basis—absolute dry weight plus 11 per cent moisture. Quotations are often given on invoice weight, which is conditioned weight plus a 2% margin for variation.

A conditioning house, besides examining for weight, also conducts numerous other tests necessary to conditioned silk. The main factors taken into consideration, besides weight, are size, color, cleanliness, boil-off, winding strength, elasticity, and general uniformity.

[Sidenote: _Weight_]

As regards size, the unit is the denier, an ancient French weight equal to .05 gram; the size is measured by the weight in deniers of 450 meters of the thread. As previously stated, the 13/15 denier size is the standard used in the United States, although the larger and smaller grades are dealt in to some extent for special types of products. Size is always given as averaging between certain deniers (such as 13 to 15) as it is impossible to attain absolute accuracy in reeling, and slight variations cannot be avoided, either within the bales or within the skeins themselves.

[Sidenote: _Color_]

The color test is concerned merely with uniformity in shade, which makes accurate dyeing possible. The cultivated silks are either pure white or yellow, according to the variety of cocoon from which they are derived.

[Sidenote: “_Boil off_”]

The term “boil off” refers to the amount or percentage of gum on the filament. As explained before, the individual strands of fibre adhere together through a gummy substance secreted by the worm. The amount found in the reeled silk varies with different kinds from 10 to 25 per cent by weight—which is brought down to a minimum by the boiling process.

[Sidenote: _Winding Strength_]

Winding strength is measured by the breaks that occur in winding. In this country the test is based on the number of breaks occurring in 30 or more skeins wound at the rate of about 120 yards per minute. This test is extremely important since a weak thread can do much to hinder an efficient re-reeling process, inasmuch as each break stops the machine and must be tied by the operator.

3. GRADING AND QUOTATIONS

[Sidenote: _Classification_]

[Sidenote: _Difficulties in Grading_]

The question of classification of raw silk for market and the various terms used for its purchase and sale is a complicated one. Standardization has been sought after for a good many years and committees both here and abroad have studied the problem on various occasions—but without entirely satisfactory results. The chief source of trouble appears to lie the many types of variation that may occur, not only on account of the great number of qualities required in the product, but also due to the varying conditions under which the silk is produced. In the early days of the industry, when farm production was the chief source of supply, particularly in Japan and China, satisfactory grading was almost an impossibility. However, now that sericulture and reeling has come more and more into the hands of the large companies and filatures, a greater degree of standardization can be reached.

[Sidenote: _Quotations_]

The following is an actual example of a recent quotation list in the New York market as it appeared in a commercial paper:—

JAPAN

(Ninety Days’ Basis, 13-15 Denies)

Kansai Double Extra Cracks $6.15 @ $6.20 Kansai Double Extra “A” 6.05 @ 6.10 Kansai Double Extra “B” 6.00 @ 6.07 Kansai Best Extra 5.95 @ 6.02 Kansai Extra 5.90 @ 5.97 Kansai Best No. 1 to Extra 5.87 @ 5.95 Kansai Best No. 1 5.85 @ 5.92 Kansai No. 1 5.82 @ 5.90 Sinshiu No. 1 5.77 @ 5.85

CANTON

(Ninety Days’ Basis)

King Seng gr. 14-16 $6.40 Favorite—Double Extra 20-22 6.00 Favorite—Double Extra 22-26 5.90

SHANGHAI

(Ninety Days’ Basis)

CHINA STEAM FILATURE Gold Double Deer, new crop $7.50 Geranium, new crop 7.25 Comet 6.60 Tsatless Blue Dragon and Flying Horse 5.60 Black Lion, No. 1-2 5.10 Tussah—Best chops 3.90

ITALIAN

Grand Extra Classical $7.00 Extra Classical 6.80 Best Classical 6.70

[Illustration:

RAW SILK PRICES NEW YORK MARKET 1913-1923

Courtesy of The Silk Association of America ]

[Sidenote: _Kansai and Sinshiu_]

In the Japanese classification, Kansai and Sinshiu originally indicated the section of Japan where the silk originated, but of recent years they have come to mean hard or soft natured silks respectively. The “Sinshiu No. 1” is usually considered the standard quotation to use in judging the market trend.

[Sidenote: “_Chops_”]

The Chinese quotations are probably the most difficult to understand since they go almost entirely by “chop”—that is, well-known brands which are marked in some distinctive way, as shown on the above list of quotations.

## CHAPTER IV

MANUFACTURE OF THROWN AND SPUN SILK

We have covered in the preceding chapters the culture of raw silk, its reeling, and finally its marketing in the countries where it is to be manufactured into the finished textile. We now come to the mechanical phases of the industry, by which raw silk is made first into yarn and then into fabric. Whereas, in the case of cotton and wool, we have seen that yarn is manufactured by various modifications of the spinning process, this is not true in the case of silk. The spinning process is here supplanted by an operation known as “throwing,” and is resorted to only in the manufacture of yarn from the various kinds of silk waste.

1. THROWN SILK

[Sidenote: _Necessity for Throwing_]

The ordinary raw silk, as it comes from the filature and is sold in the market, is composed of from two to eight filaments adhering together by virtue of the natural gum secreted by the worm. This thread is too thin and delicate for many uses and so must be submitted to further twisting and doubling—a process called “throwing.” It must be borne in mind, however, that there are several types of fabrics in which raw silk is used without going through the throwing operation. This is usually the case, for example, with the warp threads for crepes, charmeuse, and messaline.

[Sidenote: “_Throwsters_”]

Although some of the larger silk mills have their own departments for this process, as a general rule it is done by independent concerns known as “throwsters”—who specialize in this particular operation. Machinery of a very complicated and accurate type is necessary, capable of operating at very high speed. It has been found that the investment called for to equip such a mill is too large in most cases to allow the manufacturers to incorporate this operation in their factories, particularly if it happens that the spindles are not fully employed during the whole of the year.

[Illustration: _Throwing Machines_]

[Sidenote: _Organzine and Tram_]

There are two main classes of thrown silk—organzine and tram—the former has a heavy twist and is used for the warp; while the latter is given only a light twist and is used for filling. Within these two general types there are many special grades, according to the type of material for which they are to be used, such as crepe, chiffon, sewing thread, floss silk, embroidery silk, etc.

[Sidenote: _Soaking the Raw Silk_]

The raw silk as it comes to the throwing mill is done up in books of skeins and packed in bales, as described in a previous chapter. The skeins, after being weighed and examined, are first soaked for about twelve hours in warm soapy water, which softens the natural gum, after which they are thoroughly dried. This, of course, reduces the moisture content below the customary 11 per cent, which is later restored by natural absorption.

[Sidenote: _Winding_]

The first step in the actual throwing is the winding of the thread on bobbins. The skeins are put on swifts—a light type of reel—and wound at a very high rate of speed on the proper size of bobbin. It is here that the winding strength of the silk meets its severest test, for constant breaks during the winding involve considerable expense when speed is such an important factor.

[Sidenote: _Twisting_]

The bobbins of silk are next taken to the twister, which combines two or more strands and gives the thread the necessary amount of twist for the special type that is desired. In the case of tram a very light twist is given, about two or three turns to the inch. For organzine the single threads are first given sixteen turns to an inch in one direction, then doubled and twisted fourteen turns in the other direction.

[Sidenote: _Crepe_]

Twisting is the basis of the manufacture of the various kinds of crepe. The filling or tram used is given a very hard twist, about sixty-five turns to the inch—either in right or left-hand direction. These threads are later woven alternately and so produce the crinkled effect.

Thrown silk is classified in a similar way to raw silk, except that usually market quotations on thrown silks mention not only the classification but also the purpose for which it is to be used (tram or organzine), the size in deniers, the number of threads and twists to the inch.

2. SPUN SILK

[Sidenote: _Spinning Waste Silk_]

The above processes refer only to throwing of raw silk. In the case of waste, schappe, frisons, etc., an entirely different method must be used, comprising a series of operations very similar to the carding, combing and spinning of wool.[8] The gum, of which silk waste contains a very large proportion, must first be boiled off in a hot soapy bath or allowed to ferment in vats, the latter method being used more generally in Europe. After degumming, the waste silk is next washed and dried and allowed to absorb the 11 per cent moisture content, as in the case of the thrown silk. This is followed by picking, combing, and dressing to remove any dirt or other foreign matter and to separate the fibres and arrange them in parallel order.

The silk is next separated into short laps, then drawn out into thin slivers by means of drawing frames, and thoroughly combed to make the fibres smooth and uniform. These slivers are finally made suitable for winding on bobbins by being passed through roving frames. Then follows the actual spinning process, which twists the roving into yarn. Different types of yarn are produced by varying the amount of twist and the number of strands used. Single yarn is made by twisting a single strand on itself, while for 2-ply, two yarns are twisted together, and so forth, as in the case of cotton or wool.

After being cleaned and examined, the yarn is wound into skeins of about 5 ounces.

[Sidenote: _Uses of Spun Silk_]

The principal use of spun silk is in mixed fabrics, in conjunction with wool, cotton, or raw silk, the spun silk thread generally being used as filling rather than warp. The better grades are made into velvet and plush and various types of knit goods. Although high quality spun silk often has the strength and wearing quality of thrown silk, it never can compete with the latter in regard to lustre.

[Sidenote: _Sizing_]

Spun silk is described as to size in one of two general ways. In the English system the number of the yarn is the number of hanks of 840 yards weighing a pound, with a second number indicating the ply. Thus, size “20-2” would designate a 2-ply yarn, a pound of which contained 16,800 yards. The French system is more or less on the same principle, the main difference being that the number of the yarn indicates the thousands of metres weighing a kilogram.

[8] See Part Two, Page 74 to Page 78 for details of spinning.

3. MARKETING THROWN AND SPUN SILK

Thrown and spun silk are bought and sold in very much the same way as is raw silk, although the market is not as extensive nor is the volume of trading as large. The following tables of quotations are from a recent silk journal. A comparison with the quotations given in Chapter III will show the appreciation in value of the various gradings through the throwing and spinning processes.

THROWN SILK

ORGANZINE Double Extra Crack $7.30 Double Extra 7.20 Extra 7.10 TRAM Extra $6.85 Best No. 1 6.75 Kansai No. 1 6.70 Japan Crepe Twist, 2 thread, 75 turns 7.80 Japan Crepe Twist, 3 and 4 thread, 60-65 turns 7.25 Canton Crepe Twist, 3 and 4 thread, 60-65 turns 7.20 Hosiery Tram 6.75

SPUN SILK

2% net 30 days 6/2 $4.25 10/2 4.35 20/2 4.75 30/2 5.15 40/2 5.35 50/2 5.50 60/1 4.45 60/2 5.60

[Illustration: _Twisting on New Warp Threads_]

[Illustration: _Modern British Loom_

Shown at the British Empire Exposition

Wembley, 1924]

[Sidenote: _Imports_]

Although far from approaching raw silk, the importations of silk waste to this country reach quite substantial figures, as the following table shows:

Raw Silk Waste Silk 1920 30,058,374 9,400,985 1921 45,355,095 6,849,369 1922 50,711,826 7,638,317 1923 49,505,581 12,101,420

(Courtesy of Silk Association of America)

## CHAPTER V

WEAVING AND FINISHING

1. WEAVING

The manufacture of thrown and spun silk into the finished material, whether by weaving or knitting, varies with the different types of fabric desired. But the several processes are based on the same general principle and are very similar to those used for cotton and wool. To avoid repetition we would refer to Pages twenty-six to twenty-nine and Pages thirty-one to thirty-five, where full descriptions will be found.

2. FINISHING

[Sidenote: _Boiling Off_]

The first step in the finishing of fabrics is dyeing—unless it has already been done before weaving. A considerable proportion of silk is dyed in skein or yarn form before weaving, but in either case the methods of dyeing are practically the same. Preparatory to dyeing it is necessary to boil off the natural gum by means of hot soap baths. If the silk is to be dyed in dark colors a considerable amount of the gum is allowed to remain. Such silk is known as souple silk and is used principally for filling. If all the gum has been removed, it is called bright silk.

[Sidenote: _Bleaching_]

All silk, after boiling off, should be nearly pure white. Raw silk, as mentioned in a previous chapter, is often bright yellow, but as this color is entirely in the gum, it is lost by boiling off. In the case of uneven coloration in the raw silk, it is necessary to resort to bleaching before dyeing in order to get uniformity in the finished product. This applies particularly to wild silks, such as Tussah, which are bleached by being placed in an air-tight room filled with a chemical preparation, such as sulphur gas or sodium or hydrogen peroxide. A further washing and drying is then necessary before the skeins or goods can be dyed.

[Illustration: _Jacquard Loom_]

[Sidenote: _Dyeing_]

[Sidenote: _Mordant Dyes_]

There is no standard dye used for silk, some manufacturers preferring one type and others, another. It may be said, however, that as a general rule silk is dyed by the direct method, without the use of an intermediate or mordant agent as in the case of cotton. This is made possible through the natural absorptive powers of silk fibre. Mordant dyes are sometimes used, it is true, salts of tin or iron being employed as the agent; but this method is useful principally when it is desired to weight the silk and restore what was lost in boiling off. As this loss generally amounts to about 20 or 25 per cent and as raw silk is sold by weight, it is easy to see that this, unless recovered in some way, would reduce the manufacturer’s profit considerably.

[Illustration: _Winding Thrown Silk into Skeins for Dyeing_]

[Sidenote: _Weighting Silk_]

The process of weighting silk has been greatly abused, as it is comparatively simple to adulterate it, without discovery, to such an extent that the properties of the fibre are seriously impaired. Weighted silk never has the strength or wearing quality of the unadulterated product. However, a certain amount of weighting—to restore a part of the degumming loss—is generally recognized as legitimate, although the percentage permissible is often a matter for discussion.

Both skein and piece silk are dyed by being immersed in vats containing the hot dye solution. The silk is run over rollers which insure even coloration throughout. After dyeing it is dried, stretched on a tenter frame and then submitted to dry heat which sets the dye and adds luster to the silk.

[Sidenote: _Printing_]

Printing is also used for coloring and pattern effects in very much the same way as for cotton goods. After printing the goods are submitted to a dry steam heat which sets the colors.

[Sidenote: _Finishing_]

Beyond dyeing or printing, silk goods require very little finishing other than calendaring by passing through rollers. Some types of fabric require softening and others, hardening—accomplished in a variety of ways too numerous to describe. Many of these are secret processes perfected and patented by individual companies. A multitude of different effects can be obtained by these various treatments of the surface of the goods.

## CHAPTER VI

ARTIFICIAL SILK

1. EARLY DEVELOPMENT

[Sidenote: _Chardonnet_]

The discovery of what is known as “artificial silk” is generally attributed to a Frenchman, Count Hilaire de Chardonnet, who after many years of research and experimentation, between 1840 and 1890, finally perfected a fibre that possessed the necessary qualities for practical weaving. He introduced his discovery to the public in 1891 at the Paris Exposition, and in addition to winning the “Grand Prix” was also made a knight of the Legion of Honor in recognition of his contribution to science and industry.

[Sidenote: _Further Development_]

Since that time others have contributed to the development of the new fibre and discovered other methods of production—all, however, based on the same general principle as the Chardonnet process. Despaisses and Panly, two Frenchmen, and Stearn, Cross and Bevan, Englishmen, are the outstanding names in this work.

2. VARIOUS PROCESSES

[Sidenote: _Use of Cellulose_]

All the processes that have met with any success are based on the use of cellulose in some form, as a foundation. The two sources that have proved most successful are wood-pulp and cotton and it may be said that the bulk of the artificial silk on the market comes from one or the other of these two raw materials.

[Sidenote: _Chardonnet Process_]

The Chardonnet process uses cotton as its base. It is first bleached, then by chemical treatment is changed to nitro-cellulose, which is dissolved in alcohol and ether and thus made ready for “spinning.”

[Sidenote: _Viscose Process_]

The Viscose process, which has made great strides in recent years, makes use of a pure grade of sulphite wood-pulp. This pulp is in sheet form and is first treated with a solution of caustic soda, then shredded very fine and put through several more chemical treatments, finally being dissolved in water preparatory to the “spinning.”

[Sidenote: “_Spinning_”]

In both of the above methods the production of the thread is the same. The solution, whether it be based on cotton or wood-pulp, is forced through minute holes and comes out in a thread-like stream, which solidifies when subjected to a setting bath. It is then washed, dried, and put through processes, such as twisting, reeling, etc., very similar to those which natural silks undergo.

3. USES OF ARTIFICIAL SILK

The uses of artificial silk are many and are not entirely confined to combinations with other textiles. Of recent years the knitting trade has adopted it extensively, particularly in hosiery, sweater and underwear manufacture. In weaving, it has proven very successful in combination with silk or cotton. Large quantities are used in ribbon, electric cord covering, yarns, threads, etc. It is generally felt that the new fibre does not directly compete with or replace natural silk, but rather occupies its own place in the trade on the same basis as the other textiles.

[Sidenote: _Growth of the Industry_]

It has only been during the last fifteen years that artificial silk has been a very important factor commercially, although for a few years before that time, small quantities were produced in Europe. Since about 1910 its use has been steadily growing in this country, the importations from Europe increasing in 1912 from about one and one-half million pounds to nearly three million pounds in 1914. Since 1910 domestic production has also become a factor in the market and numerous factories have been established, the figures for 1923 showing about 33,000,000 pounds output. It is estimated that in 1922 the combined importations and domestic production amounted to around 20,000,000 pounds, about 50% of the total consumption of natural silk for that year.

[Sidenote: _U. S. Production_]

The following figures show the production of artificial silk in the United States in 1913 and between 1920 and 1923:

1913 1,566,000 pounds 1920 8,000,000 ” 1921 15,000,000 ” 1922 24,000,000 ” 1923 33,000,000 ”

[Illustration: IMPORTS OF RAW SILK

INTO THE

UNITED STATES OF AMERICA

CALENDAR YEAR 1914-1923

Courtesy of The Silk Association of America]

THE INTERNATIONAL ACCEPTANCE BANK, INC. AND THE SILK TRADE

THE INTERNATIONAL ACCEPTANCE BANK, INC., finances annually the importation of millions of dollars worth of SILK from China, Japan, and Italy.

THE INTERNATIONAL ACCEPTANCE BANK, INC., can offer exceptional facilities for opening commercial letters of credit in the Far East by reason of its large net-work of correspondents, and particularly because of its close relation to the NETHERLANDS TRADING SOCIETY, with branches throughout the Far East, which is one of its leading shareholders. Through its close relationship with this institution, and with many other Eastern banks, THE INTERNATIONAL ACCEPTANCE BANK, INC., can obtain for its clients a highly efficient service and can give them the benefit of the confidential information which it receives.

Transcriber’s Notes

pg 74 Changed: from horizonal spools on to vertical spindles to: from horizontal spools on to vertical spindles

pg 78 Changed: then compressed betweeen rollers to: then compressed between rollers

pg 91 Changed: further into hitherto uninhabitated to: further into hitherto uninhabited

pg 124 Changed: It is then washed, dryed to: It is then washed, dried