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Historical Sketch Of The Textiles
Mechanical Devices For Preparation Of Textiles
Geography Of The Cotton Trade
Prices Of Cotton Goods
Classes Of Wool
Production Of Wool
Manufacture Of Wool
Geography Of Wool Production
Mohair, Its Nature And Uses
Raw Silk Porduction
Imitations Of Silk
Construction, Color, And Finish Of Cloth
Dyeing And Printing
Care Of Textiles
( Originally Published Early 1900's )
Sources of silk waste.-In the production and manufacture of silk a large part of the cocoon fiber is unfit for reeling or working up into the finest grades of silk fabrics. As in the manufacture of cotton and wool, there is considerable waste of raw material in the many processes and machines that are required. This so-called waste is by no means wasted. It is all carefully collected and used in the manufacture of goods differing only in grade from the highest priced fabrics.
Most of the wastes originate in the reeling process. First there is the outer part of the cocoons, the floss, which must be brushed off before reeling can begin. Then there is the inner part of the cocoon next to the chrysalis, which can never be entirely reeled off. Then, too, there are always a large number of imperfect cocoons that yield little or no fiber suitable for reeling. All cocoons left for binding purposes and pierced at the end cannot be reeled and must be converted like other silk waste. Nor must we forget the waste fibers from the reel, short and tangled, and all needing to be worked over. Clippings, loose threads, and so on from dressmakers' establishments, from the silk goods manufactories, and from ragpickers' carts are all reclaimed and made into silk shoddy by running through shedding machines that tear up the material into fine floss. The process closely resembles that used in making wool shoddy.
Variations in methods of use.-Naturally the method of utilizing silk wastes varies considerably according to the character of the waste. Raw waste from the cocoons needs a treatment differing from that given to silk shoddy. Short fibered waste is treated differently from long-fibered waste, while colored waste goes through processes not at all used with white or uncolored wastes. Obviously, the first step in the manufacture of silk wastes is classification of the material into as many varieties as may seem practicable. Some of this sorting and classifying is done by the producers of raw silk, some by the silk rag dealers who" gather the wastes from makers-up, but most of the sorting is done in the silk manufactory.
Degumming raw silk waste.-If the silk waste is raw, the first step is to remove the gum or sericin. There are two methods commonly employed, one usually practiced in France, Italy, and Switzerland, and the other in England and this country. The first is called the schappe method, and the latter is called the boiling off method. In the schappe method the raw silk waste is turned into large vats in rooms that are kept damp and warm. Here the silk begins to ferment, and this fermentation loosens the gum so that it may be washed away easily. The odor given off by the fermenting silk is so intensely offensive, however, that all such silk-washing plants must be located far from any human habitation. Workers in the plants grow accustomed to the stench and mind it comparatively little. The advantages claimed for this method are that the silk fiber left after washing is very glossy and that its strength has not been impaired in the least, if the fermentation is stopped at the right time.
Boiling off method.-The English method consists in dumping the silk waste into cotton cloth bags and immersing them for some time in boiling soapsuds. This loosens the sericin or gum quickly and without any offensive odor.
This boiling process is about the same in principle as that employed in removing the gum from the reeled silk. Conditioning.-After the silk waste has been degummed it is ready for conditioning. It is washed, and then dried to the point where it will work best in the subsequent mechanical processes. Especially if it is to be sold before going through further processes, the conditioning as to the right amount of moisture is looked after very carefully before the goods are finally weighed out. Some moisture is necessary in order to have the silk work smoothly without becoming charged with static electricity.
Beating and opening.-The next process in its manufacture is running it through a machine called a beater. The fibers are pounded and beaten thoroughly to loosen them from each other and to dislodge any foreign matter not dis solved in the boiling off or degumming process. From the beater the fibers are passed into another machine called an opener. This loosens all the lumps and makes the whole mass more fluffy. When the waste is made up of very long fibers, they are sometimes cut up into smaller pieces which will work more easily and smoothly.
Carding and combing.-The next machine, known in England as a filling engine, cards and lays out the loose fibers in thin laps or strips similar to the card laps in the cotton and woolen industries. In all the better grades of silk waste, the next step is combing. This process is very similar to wool combing in the worsted industry, but in spun-silk manufacturing it is called silk dressing. The lap is run into the combing machine and the combed fiber may be re-combed again and again, often as many as five or six times. Each combing is known as a draft. A considerable amount of silk noil is separated from the fiber. The better noils are mixed with loose silk waste to be worked over again. Medium grades of silk noils are used in making noil yarns and as such are frequently used in making silk and wool mixtures. The shortest noils are mixed with the coarsest and poorest waste silks. These are not combed at all but simply carded and spun into yarn as in making yarn of short-fibered cottons.
Drawing and spinning.-After the waste silk is properly combed the silk tops are put through gill boxes and drawing frames and reduced first to slubbing and then to roving in the same way as in combed wool production. The rovings are next spun on mule frames and usually doubled. This completes the spinning process. The yarns, after being finished by singeing or gassing so that all fuzziness may be destroyed, are ready for weaving.
Qualities of spun silk.-Spun silk is not quite so lustrous as thrown silk although it still retains much of the appearance and quality of that product. Nor is it so strong as thrown silk. But in both strength and luster much depends upon the quality of the waste from which it is made up. Length and evenness of fiber very largely determine the appearance. The care used in dressing and spinning also adds to the strength and luster.
Sometimes the silk waste is spun in the gum and the degumming process is not applied until the manufacturing processes are completed.
Uses of spun silk yarns.-The best grades of spun silk yarn are used as filling or weft in several varieties of silk fabrics, both plain and twill, and in pile goods such as velvets. Spun silk yarn of high grade is also used as warp in goods that have a cotton or wool filling. A considerable amount is used in the production of embroidery and knitting silks.
Lower grades of spun silk yarns are used in making ribbons and silk cords, while the cheapest grades are used in making knit goods and the poorest and coarsest silk or silk-mixed fabrics. The poorest grades of spun silk, those which are carded only and not combed, are used as filling in cheaper grades of silk dress goods,in the silk upholstery fabrics in polishing cloths, and in coarse grades of knit goods.