The value of silk permits of no unnecessary waste and this control is important. The skeins are then examined for any defects. These consist of small knobs on the thread like pin heads, or a very coarse piece 3 or 4in. long due to a cocoon not unwinding evenly. The knobs are picked off, the coarse pieces removed and clean thread is inserted in their place. The skeins are twisted up and packed into a bale.
Silk Waste.—The outer covering or fluff which is brushed off the cocoons in finding the filaments is a valuable waste used by silk spinners. Its trade name is knubs (Fr. frisons). A thin film of silk is left round the chrysalis when reeling is completed. The chrysalides with this film are boiled up in a vat and stirred with beaters which tear the film off. This is a low grade waste also used by spinners. The chrysalides are dried and form a valuable manure. Thus nothing is lost.
Throwing.—Raw silk, being too fine and delicate for ordi nary use, next undergoes a series of operations called throwing, the object of which is to twist and double it into more sub stantial yarn. It is as raw silk that the thread is shipped to the principal manufacturing countries of the world; that is, the United States of America, France and England. The word "throwing" originates with the old Anglo-Saxon term "thrawan," meaning to twist. The man engaged in such work is known as a "throwster" and the product is termed "thrown silk." In the United States, throwing is a service performed chiefly by the commission throwster, or one who will prepare, for a fixed price per pound, the raw silk sent him by the owner. Some throwsters buy the raw silk direct from the importers, throw it and sell the thrown silk, as required, to manufacturers of fabrics or hosiery. The silk is shipped on spools or cones, the latter for the hosiery trade. It may also be shipped as skeins, and prior to the middle of the loth century, silk was prepared only from skeins dyed prior to weaving. The evolution of crepe fabrics re sulted in the development of piece-dye fabrics or the weaving of fabrics directly from the thrown silk, without colour, and its dye ing or printing later in the woven piece. The reason for handling crepe in this manner can be readily seen by taking a tightly twisted piece of thread and attempting to make it lie straight.
The resulting snarl demonstrates the necessity of winding crepe threads directly onto a spool or bobbin and waiting until the thread is bound into a fabric before it is dyed.
It is in the throwing process that silk shows itself as different from other textiles. The magic thread from the silk cocoon is already one continuous strand and does not need the combing and preparation required by the shorter fibres of cotton and wool. The only refining process needed before weaving is that of pro ducing different effects in the finished fabric by twisting the silk thread to varying degrees. In weaving some fabrics, no throwing is required. In general, however, silks are thrown and the types are organzine, crepe, tram and singles. Crepe is customarily spoken of as a separate type although technically it is organzine with a higher number of turns per inch: 4o to 80. Organzine is the result of doubling two or more threads, previously twisted as single threads and twisting them in the opposite direction 8 or io turns to the inch. This type of yarn is used chiefly for the warp or lengthwise thread. Tram, on the other hand, is used for the filling or crosswise thread and begins with the raw silk thread without doubling. Two or more threads are twisted together with a few turns per inch. Singles are the raw silk threads both twist ed and untwisted. When twisted hard, "hard twist," the yarn goes into chiffons and sheer fabrics.
Untwisted, it makes such cloths as the Japanese "habutae," often misnamed China silk.
Throwing is considered the least skilled operation in the manu facture of silk. It employs women workers chiefly and is found where a plentiful supply of relatively unskilled labour is avail able and power is cheap. In the United States, this is principally in the coal mining regions of Pennsylvania. The wives and other female relatives of the miners find in the light, clean work a satisfactory means of adding to the family income. The local sup ply of coal provides the second need of cheap, plentiful fuel for power.