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Old And Sold Antiques Digest Article

Textiles:
Textile Fibers
Historical Sketch Of The Textiles
Mechanical Devices For Preparation Of Textiles
Cotton Production
Cotton Marketing
Cotton Manufacturing
Geography Of The Cotton Trade
Prices Of Cotton Goods
Linen
Classes Of Wool
Production Of Wool
Wool Marketing
Manufacture Of Wool
Geography Of Wool Production
Mohair, Its Nature And Uses
Raw Silk Porduction
Silk Manufacturing
Silk Waste
Imitations Of Silk
Construction, Color, And Finish Of Cloth
Dyeing And Printing
Cloth Finishing
Care Of Textiles
Textile Tests

Imitations Of Silk

( Originally Published Early 1900's )



Reasons for imitating silk.-Silk, the most beautiful as well as the strongest of all textile fibers, is naturally in strong demand the world over. Nothing but its high cost of production prevents its more general use. One does not wonder that there is much interest in finding substitutes for this great fiber, or cheaper materials which combine as many of the qualities of true silk as possible; such, for example, as its high luster, its steel-like strength, its attractive smoothness and softness, its elasticity, and its quality of taking the most delicate tints and shades in the dyeing process. Many experiments have been tried, much money has been expended, and much human energy exhausted in the desire to find such suitable substitutes. Many vegetable fibers such as cotton, ramie, linen, wood fiber, kapok, and others have been used in one way or another with some degree of success. Various finishing processes have been invented to give to cheaper fibers the appearance of silk, such as gassing or singeing, glossing, beating, and polishing.

MERCERIZED COTTON

None of the imitations of silk has been more widely adopted than mercerized cotton. Mercerization is a process applied to cotton yarns or fabrics which gives to the cotton fiber a silk-like luster, a somewhat greater strength than that of ordinary cotton, and a greater affinity for dyes. Mercerized cotton is at the present time a direct competitor of silk in a great number of ways, both as an imitation and as a substitute. Its qualities are so excellent, however, that were it not for its value as a silk substitute it would still rank above ordinary cotton in its own right. Mercerized cotton has proved itself a most desirable addition to the textiles.

John Mercer.-The process of mercerizing cotton was discovered about 1844, by an Englishman named John Mercer, but he thought so little of his discovery that he took no patent on the process until 1850. At the time of his invention, he was a chemist in a large calico printing plant. His name is well known in textile chemistry. Besides mercerization, he invented several styles of calico printing and prepared for the first time a sulphonated oil (known as Turkey red oil) ever since used in producing certain fast dyes. He was the inventor of the blue-print photographic process, and also of several medical or pharmaceutical preparations.

Story of mercerized cotton.-Samples of mercerized cloth were exhibited at a world's fair in London in 1857 and attracted considerable attention; but the cost of the chemicals used in mercerizing was then so high that the process seemed hardly feasible. Mercer, who died in 1866, was therefore in no way benefited by this valuable invention. Not until the later eighties did mercerization become practical, and then for two reasons. First, certain improvements were discovered in the methods of mercerizing; and, second, the cost of the needful chemicals had considerably lessened since Mercer's time. By igoo mercerized cotton was in extensive demand and the annual production and consumption have climbed every year since then. Its use is now widespread in a great number of fabrics, as the sole textile in some cases, as the warp in others, as filling in still others. In almost every sort of fabric in which silk is used, mercerized cotton is also employed. Its cheapness permits its use in a number of things for which silk would be impracticable because of prohibitive cost.

The mercerizing process.-The process of mercerization is simple in principle. It consists simply in soaking the cotton or other vegetable fiber in strong caustic soda or caustic potash solutions for a few moments and then washing in pure water to remove the caustic. The resulting change in the fiber as to appearance and quality is called mercerization. What actually takes place may be briefly explained. It will be recalled that cotton fiber is composed of almost pure cellulose. Caustics, when strong, attack these cellulose fibers, causing them to swell in diameter and contract in length. In natural condition the single cotton fiber is a flat, ribbon-like filament, but when immersed in caustic solutions it swells out and takes on a round and hair-like appearance, plump instead of flat. The difference between a mercerized fiber and an untreated fiber can be seen easily under a microscope. This change in form of the fiber is accompanied by a change in the substance. The cellulose is changed into another kind of chemical substance called cellulose hydrate or hydro-cellulose. The principal difference between this substance and the old cellulose is that it has a much greater affinity for dye substances. Cellulose cannot be dyed very easily except with certain very powerful dyes. Hydro-cellulose, on the other hand, absorbs almost any kind of dye readily and quickly. In fact, in dyeing mercerized cotton, it is customary to put in chemicals to check the process in order that the dyes may not enter so rapidly as to render the shading uneven.

Qualities of mercerized cotton.-Loose cotton fibers placed in the caustic solution contract considerably, thus increasing the strength of the fiber. Hence, mercerized cottons, unless stretched too much, are generally considerably stronger than untreated cottons. Not only does the contraction of the fiber strengthen it, but also the thickening of the diameter due to the expansion already described stiffens the structure of the fiber. This much Mercer discovered in 1844 and described in his application for a patent in 1850. But the silk-like luster that we now look for in mercerized cottons had not yet been developed. About i8go some textile makers in Germany were experimenting with the mercerizing process on yarns and woven cloth. It was found, as has already been suggested, that the process shortened the fibers, and consequently caused a noticeable shrinking in the yarn and cloth. This, the experimenters felt, was a disadvantage, and so they concluded that they would attempt to prevent this shrinkage by stretching the cloth and keeping it stretched full length while it was being mercerized. They were successful in keeping the fabric from shrinking, but what was their surprise, on taking the cloth out of the caustic and washing it, to find that it had a beautiful, silk-like luster! The commercial possibilities of this discovery were not overlooked. A description of the process was quickly rushed to the patent offices of all countries, and mercerized cotton, glossy, smooth, and strong, became a big factor in commerce within a few years. Under the low tariff of the Democratic administration from 1893 to 1897, European mercerized cottons were introduced into America, and American manufacturers presently began to produce the same sorts of goods for home consumption. Since 1903 the use of mercerized cotton has increased by leaps and bounds in about the same proportions as silk has increased in American use. When the fashions dictate a great vogue in silks, then mercerized cotton likewise leaps forward. When silks recede slightly, mercerized cotton feels the change also.

Modern methods of mercerizing.-The modern methods of producing mercerized cotton closely follow the principle discovered by Mercer, together with the improvements discovered in 1890. Yarn or cloth that is to be mercerized is first given a soap and water scouring, soaked in clean water, and then run through rollers that extract most of the moisture. Next the material is run into the caustic solution bath, at a temperature of about 65° Fahrenheit, where it remains from ten to fifteen minutes; longer would prove disastrous to the fabric. Sometimes the material is run through this bath in stretched condition; more frequently it is simply soaked in the caustic, removed, and then stretched before being rinsed. This seems to give the best results. After the cloth or yarn is stretched to its original length, it is washed in water to which acid has been added to counteract the action of the caustic in the material. Sulphuric acid is the cheapest and most commonly used. Its use requires care, however, for slight overuse would harm the mercerized cotton as much as overexposure to the caus tic. Acetic acid is not infrequently used since it is not at all dangerous to the cotton fiber and has the added advantage of giving to the mercerized cotton the feeling and the ten. dency to rustle, the "scroop," as it is called, that is found in true silk. Acetic acid is more expensive than sulphurie acid. Tartaric acid produces effects similar to acetic acid,

Bleaching generally follows the mercerizing process, because, if done previously, it slows down the mercerization, whereas mercerization is not affected by subsequent bleaching. The fabric is now ready for the finishing processes such as dyeing, singeing, polishing, and calendering. An excellent luster is obtained by singeing or gassing the yarns before they are mercerized. Too many of the little fine linty hairs found on the surface of cotton yarn dull the luster; hence, gassing is necessary either before or after the mercerizing process.

Any strong caustic causes cellulose to mercerize. Caustic soda, the cheapest of all, is most generally used. Caustic potash, while somewhat more expensive, gives a little better luster. Sodium peroxide gives a still better luster, although it entails other dangers, as for example, fire. Zinc chloride and several other substances are suitable but caustic soda is the most commonly used. To this a little carbon disulphide is sometimes added, which helps to give a better luster. In some cases alcohol is added to hasten the penetration or impregnation of the cotton fiber by the caustic solutions.

Several attempts have been made to bleach and mercerize in one operation and thereby to lessen the time and expense involved in the production of mercerized fabrics. No success has yet been attained in these experiments.

Mercerizing fibers other than cotton.-From what has just been said about the process of mercerization it is easily inferred that not only cotton but any fiber containing cellulose may be mercerized. Linen, ramie, jute, and wood fibers, and even paper have been successfully mercerized. But for textile purposes, since cotton is one of the cheapest and most adaptable clothing fibers, it is ordinarily used.

What cottons are best suited. to mercerization.-Any length of cotton fiber can be mercerized; where a high luster or gloss is desired, it is advantageous to begin with long fibers having as much natural luster as possible. For this reason sea-island and Egyptian cottons are best suited for the finer mercerized goods. The fibers must be stretched either in or after the caustic bath. The long fibers of seaisland cotton are more easily stretched in the yarn or in the cloth than are the upland cotton fibers. Short fibers must be spun into hard-twisted yarns in order to stand the pull; this hard twist in the yarn of such cottons makes it somewhat difficult for the caustic solution to penetrate evenly. The long fibers of sea-island or Egyptian cotton can easily stand the stretching process even in a loosetwisted yarn.

Cottons are combed rather than carded.-Yarns to be mercerized are combed rather than carded, and it is not unusual to double-comb the fibers in order to make sure that all lie as nearly parallel as possible. After the combing process, any needed twist is given, after which the yarn may be gassed, as already suggested, before treatment in the caustic bath.

Stretching.-Some manufacturers have experimented to see just how much stretching is necessary to get the highest luster. There is considerable difference of opinion upon this point. Some claim that the highest luster is obtained by stretching almost to the breaking point; others claim that no additional luster can be gained by stretching cloth or yarn beyond its original length. It seems certain, however, that high degrees of luster found in mercerized cotton are almost always accompanied by a weakening in the strength of fiber. Mercerized yarn that has not been stretched is much stronger than the same size of ordinary cotton yarn. Even when the mercerized yarn has been stretched to its original length, the length before treatment with caustic, it is still somewhat stronger than ordinary yarn. Stretching it beyond this point, however, increases the luster at the expense of fiber strength.

Uses of mercerized cotton.-Mercerized cotton answers many purposes. It is found in such materials as sateens, silkoline, tubsilk, cotton taffeta, linings, dress goods, skirtings, and in embroidery and crochet yarns in its own name. But it is also used in a great number of so-called silk-mixed fabrics, such as silk-mixed mohair, silk-mixed alpaca, silkmixed woolen and worsted figured goods, silk-mixed worsteds for men's wear, silk-mixed cottons, and so on. It is frequently used in figured cotton damask tablecloths and napkins. Mercerized cottons likewise figure largely in upholstery goods, draperies, curtains, and coverings. Producing crepe effects by mercerization.-The principle of mercerization is sometimes employed to secure crepe effects in union goods, the mercerization attacking only one class of fibers or yarns, as for example the cotton threads introduced at regular intervals in a woolen structure. Such fabrics are called crepons. Between 1895 and 1900 these fabrics had a great vogue in this country. Most of the goods were imported from Germany. How this peculiar effect was obtained was for a considerable time a puzzle ta Americans until they finally discovered that the drawn up effect, the creping, was due to the shrinking by mercerizing of cotton threads inserted at the time of weaving into the woolen fabric, the wool remaining unaffected by the process.

Special applications of mercerization.-Not always is the whole fabric mercerized in piece-goods mercerization. Sometimes the cloth to be mercerized is covered with a paste, leaving the cloth exposed only in certain places in the form of figures. In this condition the cloth is immersed in the caustic bath with the result that only the open figures are mercerized, the protected portions remaining plain cotton. The possible variations in finish may be made even more numerous by the dyeing process. Colors may be applied which dye the ordinary cotton faintly while giving the mercerized figures a very full, deep color. Another common method of part mercerization is by mercerizing the cotton cloth in stripes. This gives the seersucker effect. Several other similar types of manipulation are possible, although of interest mainly to the textile manufacturer.

SILK SURFACING

Another method of so treating cotton yarn as to make it look like silk has had considerable success, though not nearly so important as mercerizing. This method consists in soaking smooth cotton yarns in a solution of pure silk made by dissolving silk remnants and silk waste in some acid. A considerable amount of silk waste not used in spinning is disposed of in this way. The cotton yarn is first soaked in tannic acid or in some metallic acid solution, and then transferred to the silk solution bath. The preliminary acid treatment causes the cotton more readily to take up the silk solution. After soaking in the silk liquid bath, the cotton yarns are dried, run between heavy rollers, gassed, and polished. Yarn so treated has a fine silk-like appearance. The cotton is indeed covered with a very thin film of true silk. Unfortunately this finish has very little durability, and its use is limited to goods which call for little hard wear or washing.

THE ARTIFICIAL PRODUCTION OF SILK

There is still another method of imitating silk which from the standpoint of textile chemistry is really more fundamental than either of the methods just described. For a long time the chemical composition of silk has been accurately known. Its method of production by the silkworm is pretty well understood. As will be recalled, this process consists simply of giving out thin filaments from the thick, sticky mass of silk gum found in the two sacks in the silkworm's body, the filament hardening into a strong fiber as soon as it comes into contact with the air. This simple process has suggested to many persons the possibility of artificially producing a gum of the same or similar chemical composition, a gum that would harden when pulled out into a fine hair-like thread. A great French scientist named Reaumur suggested as far back as 1734 the possibility of the discovery and production of artificial silk. His own experiments were confined to the use of different kinds of varnish forced through minute holes in the bottom of sheet-iron or tin cans. The fibers hardened like true silk but no satisfactory use was ever made of them in a practical way.

Andemars.-Not until 1855 was the subject revived again. In that year a Swedish chemist, Andemars, took out patents in the various European countries on a process of making artificial silk of cellulose pulp. It will be recalled from our study of cotton and linen that both of these fibers are nearly pure cellulose. Andemars made his cellulose from the inner bark of mulberry trees dissolved in alcohol and ether. From this sticky substance he drew out threads which hardened in the air after the fashion of genuine silk fiber. Cellulose differs from the silk substance mainly in the fact that it contains no nitrogen, whereas silk is about one-fifth nitrogen.

Swan.-In 1883 an Englishman, J. W. Swan, discovered a method of making a pulp from cotton fibers by dissolving them in alcohol and ether. He passed this pulp through very small openings and then hardened it by passing it through water. The result was a number of fine silk-like threads. Swan made only a few experiments with his invention in the textile field. The product which he made was very inflammable; in fact, its composition was abouf the same as that of gun cotton or nitro-cellulose, and likely to explode with serious consequences. Few of us ardently desire to wear clothing of that character or to have our neighbors so clad. NO insurance company would insure a building in which this material was made or stored. The early prejudice aroused against artificial silk because of its inflammability exists even to this day in certain European countries. In these countries fire insurance is not sold to any producer of cellulose silk.

Chaxdonnet.-At about the time when Andemars took out his patent and continuing for several years later, a Frenchman named Chardonnet began to experiment in the making of artificial silk. He also used cotton, especially cheap cotton wastes, and made his sticky pulp paste by dissolving the cotton in alcohol and ether. Chardonnet's first factory was started at Besanqon, France. Although he was wealthy before beginning his experiments, in the course of a few years of experience with artificial silk making he went into bankruptcy. This did not discourage him. With the help of other men's capital he tried one method after another, until he achieved success in the making of artificial silk. Chardonnet ranks in the textile field with Eli Whitney, the inventor of the cotton gin, and Elias Howe, the inventor of the sewing machine. Neither of these was able to enjoy during his life any material fruits of his labor. Chardonnet, however, lived to see his invention of cellulose silk adopted as practical by the commercial world. Chardonnet silk gained the esteem of the public in 1889, when several artificial silk products were displayed at the Paris Exhibition. Commercial demand can really be traced from that date.

Chardonnet's process, as he finally perfected it, did not end all experimenting in making artificial silk. In fact, Chardonnet silk, while it is yet made in greater quantities than any other, seems destined to be superseded by better artificial silks, such as the cuprammonium and viscose varieties. But Chardonnet's process paved the way to practical use of this highly important textile. He solved the problem of making the artificial silk non-explosive; he succeeded in making it even less inflammable than ordinary cotton.

Other varieties of artificial silk.-Three other varieties of artificial silk have been tried. One of these, gelatin silk, the one which in chemical composition most nearly resembles true silk, has proved the least satisfactory. None whatever is made now for practical uses. Gelatin silk is sometimes called vanduara silk. The other two are cuprammonium and viscose silks.

Cuprammonium silk.-In making cuprammonium silk, cotton cellulose is dissolved into a paste by means of cuprammonium, or ammoniacal solution of cupric oxide, instead of alcohol and ether. The fibers are drawn in jets from the cylinder in which the paste is compressed and are hardened in acetic acid. A considerable amount of this artificial silk is made in Germany. It is known in the German language as glanzstoff.

Viscose silk.-Viscose silk is made from wood pulp, generally that of spruce wood. This substance also is mostly cellulose but acts somewhat differently from cotton cellulose. Wood cellulose is dissolved in strong alkali and carbon bisulphide. The paste formed is called viscose. This is made into fibers by being forced through tiny pipes or jets and hardened in a solution of ammonium chloride. Viscose silk is likely to be the most popular of the artificial silks. Its qualities seem to be somewhat better than those oŁ either the Chardonnet or the cuprammonium silks, while the cost of making is somewhat less. Chardonnet and cuprammonium silks are still made in large quantities in France, Switzerland, England, Belgium, and Germany, but in the one large artificial silk factory in the United States, located near Philadelphia, viscose silk is the product manufactured.

Experiments going on.-Experimentation is still going on. Great discoveries are still likely to be made in the production of this textile material. There are now nearly a score of processes besides the four mentioned above, but the three noted as successful are the ones which are used in producing fully nine-tenths of the commercial artificiat silk. It is noteworthy that the American plant near Philadelphia expended over a million dollars in tests and experiments before a pound of the yarn was sold. Recently there. has appeared the advertising of new artificial silk which does not have some of the objectionable features of ordinary artificial silk, such, for example, as the tendency to weaken and go to pieces in water.

Qualities of artificial silk.-The Chardonnet process silks together with other products made by using similar chemicals (that is, pulp, ether, and alcohol) are sometimes called pyroxylin silks. Occasionally they are called collodion silks; viscose silk is sometimes called wood silk. All of the artificial silks are very bright in luster, even more so than true silk. They are usually stiffer, and may or may not have the feel of true silk. Most varieties are somewhat harsher than true silk, and none have its elasticity. The size of the filaments varies, but artificial silk can be made as fine as natural silk. In making ordinary artificial silk the diameter of the filament is usually about 4/1000 of an inch. It takes about 33,000 yards of such filaments to make a pound. A single yarn is usually made up of from fifteen to twenty filaments. The yarn made of artificial silk is not so strong as true silk yarn of the same size, but while dry it is considerably stronger than cotton. Until recently, at least, no method has been discovered to keep the filaments from weakening in moisture. When wet, the yarns are usually not more than about a sixth as strong as when dry. This has been one of the main objections to artificial silk, since it is necessary to use it in only such goods as do not become wet or need washing.

Artificial silk seems incapable of withstanding high temperatures. At a temperature of about 300° Fahrenheit if chars and is destroyed. Cotton, wool, and true silk all stand considerably higher temperatures than this before being materially injured. Hence, artificial silk must be handled very carefully when calendered or ironed. Using flatirons at the temperatures appropriate for cotton or even true silk would ruin artificial silk.

Amounts of artificial silk used and value.-It is estimated that the amount of artificial silk used in this country at present is nearly one-fifth as great as the quantity of true silk. This is probably too large an estimate, but the amount used is certainly increasing every season. The cost of the yarns ranges from $1.75 to $2.50 a pound, whereas real silks cost more than twice as much.

Uses of artificial silk.-Artificial silk is used mainly in the production of braids, passementerie, trimmings for hats and dresses, knit neckties, curtains, tapestries, ribbons, and as the warp in certain kinds of dress goods. A recent estimate made in the Scientific American states that fully ninety per cent of all silk braids and passementerie is now made from artificial silk.

Artificial silk cloth.-Artificial silk cloth is not necessarily made in the usual way by making artificial silk threads into yarn and then weaving cloth from the yarn. A much quicker process is sometimes employed. The pulp or paste may be poured over a large flat surface rolled out thin and then marked with rollers engraved in such a way as to give the material the appearance of having been woven. In this way much millinery silk is made, as for instance, tulle or maline. The appearance is good, the cost is low, and the service is excellent so long as the fabric remains dry. Almost any sort of weave may be imitated by this process.

Mixing other fibers with silk.-Silk itself is often mixed with baser and cheaper fibers in such a way as to show an the outside any silk that exists in the fabric. Cotton-backed satins, cotton-mixed pile fabrics, silk warp cotton and wool goods, and so on are lines in which silk is so manipulated. Such treatment is entirely legitimate so long as buyers know what they are getting. Some very desirable and inexpensive fabrics are made up of silk mixed with other textiles, the beauty of the silk going far towards reclaiming and beautifying the cheaper and coarser fibers.

SILK WEIGHTING

But there is another method of using silk that is less fair, since it adds no utility to the fabric. This is silk adulteration. The most common method is by means of weighting. By means of weighting the manufacturer can take a pound of raw silk and turn out therefrom as many as three or four pounds of silk cloth or even more. The product is a cheat and even the pound of true silk used is spoiled by the addition of the weighting.

Object of weighting.-As a rule only reeled silks are weighted. Spun silk is so much cheaper that it does not pay to introduce the weighting materials and expend the time and labor necessary to increase the weight. Reeled silk is high in value and much in demand; hence the constant temptation to make the silk go farther than it really should by means of loose, sleazy weaving, the necessary weight being added by means of adulterations. Certain exceptions to this statement should be noted, however. Knit silk mufflers, scarfs, and hoods made of waste silk are legitimately weighted. The additional weight gives a better feeling to this class of goods.

Means of weighting silk have been known for many centuries, but as a commercial practice weighting does not date back much more than thirty or thirty-five years. Silk dresses made before that time cost more than they do now, but they wore proportionately better. Silk is the strongest and most durable of all textiles when properly prepared, but when weighted it loses much of its strength.

Weighting of raw silk.-The Chinese have been adepts in weighting silk. For years it was, almost impossible to get a pound of pure silk from this country. Every pound of silk yarn had been increased to two or three by means of weighting with acetate of lead. Suspicion grew to such an extent that it severely hurt the Chinese silk trade. The government of China has taken some steps to stop the practice. Foreign silk buyers have established themselves in several of the silk districts in China; they buy nothing but cocoons which they have reeled in their own filatures, to make sure that they may have nothing but pure raw silk to send abroad. Sometimes, also, weighting is applied after the raw silk has been thrown and while it is being made ready for dyeing.

Weighting substances used.-The substances used in weighting silks include tannin in any one of several forms, salts of metals such as iron, tin, chromium, sodium, magnesium, and barium, and such substances as sugar, glucose, gelatin, glycerin, and paraffin. This list by no means includes all that may be used. However, tannin, iron, tin, and sugar are the most common.

Explanation of weighting.-Weighting depends upon the fact that silk has great absorptive power. For example, a pound of pure raw silk will absorb nearly half a pound of tannin in any of its several forms before giving any visible indication of being changed in character. Furthermore tannin has a marked affinity for certain metals, such as iron and tin, in the form of chemical salts. A pound of silk loaded with tannin and soaked in solutions of iron salt will take up iron to the extent of another half-pound without any visible effect in the silk. By adding more chemicals of various kinds, the total weight of the pound of raw silk may be brought up to three or four pounds, and in some experiments has been brought up to nine pounds, before the apparent silk qualities of the yarn or cloth were lost. Silks to be given a dark or black dye will stand more weighting than light-colored silks, for the latter are likely to be discolored by too much weighting. Iron salts are most suitable and cheapest for the dark-colored silks; tin salts are used for the light-colored silks.

Methods of weighting silk.-The usual method of application of weighting is somewhat as follows. In the boiling-off process, by which the natural gum of the silk is removed, the silk loses approximately one-fifth of its weight. It has always been felt legitimate to add weighting to this extent. In fact, a silk that contains no more than this amount of weighting is called a pure dye silk. The silk' is immersed in a solution of catechu, cutch, or some other substance rich in tannin. The lost fifth is quickly replaced by the tannin. But the ease with which iron or tin may be added and the demands for silk cloth of considerable weight, cause silk manufacturers to transfer the silk from the tannin vats to the iron or tin baths. After this, the cloth is taken out, washed in pure water, and tests are made to see haw much weighting has been added. If it is felt that more will prove profitable, the silk goes back through the weighting baths again, sometimes more than once. After the weighting and washing are completed, the silks are ready for the dyeing.

Effects of weighting.-The results of weighting may be most disastrous to the life of the silk. In the first place, the fabric begins to lose its strength as soon as weighting is applied. The more the weighting, the less the strength. Wearing the silk soon causes it to disintegrate and laying it away or storing it causes it to crack or crumble. Heavily weighted silk must be worked up into garments or whatever else it is intended for very soon after it is made; otherwise in a few months it becomes useless. Spots develop in the dye after a time, perhaps because of unevenness in weighting or from other causes. Saltwater, perspiration, and tears cause spots to be formed, spots which sometimes disintegrate as if the places touched had been eaten out by strong acids. Sunlight attacks weighted silk, and, were it not for the addition of certain counteracting chemicals, would soon cause the silk to fall to pieces. No matter what one does with weighted silk, it is certain to lose its usefulness in a comparatively short time. If one uses it, it wears out; if one lays it away, it cracks, crumbles, or rots to pieces, Neither storage in light nor in darkness can save it.



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