Silk Throwing


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Silk Throwing

 

the aggregate of production processes by means of which raw silk or untwisted chemical filaments are converted to twisted yarns. Twisted silk and chemical yarns are classified according to their use: for weaving, knitwear manufacture, general use (sewing and embroidery), and technical purposes (surgical, insulating, and other types). Twisted silk is classified according to structure into simple, compound, and irregular-twist types.

In silk throwing, skeins of raw silk are soaked in a soap- or oil-based emulsion to soften the sericin, which promotes the best separation of filaments during reeling; it also imparts smoothness and pliability, increases the hygroscopicity of the filaments, and decreases their capacity to take and hold an electric charge. Chemical filaments are not soaked, but are subjected to sizing to give them greater toughness and smoothness and to decrease their tendency to accept and hold an electric charge. After soaking or sizing, the skeins of raw silk or chemical filaments are wrung, straightened, and dried. Before drying, skeins of raw silk are picked apart in order to separate the filaments and remove tangles. After drying, the skeins are unwound on winding machines, which permits control of the continuity of the filament and makes it possible to wind it onto spools or bobbins convenient for subsequent processing. During unwinding, weak and defective sections in the strand are removed.

In order to obtain a thicker yarn, several strands are joined together, usually on double twisters, with simultaneous loose twisting of the strands. This decreases the tendency of the strands to break during subsequent twisting, which is done on multistage or ring twisters. In order to produce twisted yarns of equal weight, that is, to decrease their tendency to ravel, the yarns are steamed in special chambers. After steaming, the twisted yarns are rewound into skeins convenient for subsequent processing.

Twisted silk is usually produced from two to five strands twisted together, with from 50 to 3,000 turns per m.

REFERENCE

Usenko, V. A. Shelkokruchenie. Moscow, 1969.

V. V. ZHOKHOVSKI

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Silk throwing, sometimes using water-powered machines was more restricted, and silk weaving was only significant at Vicenza in the eighteenth century.