Silk

Silk, natural fiber produced by certain insects and spiders to make cocoons and webs, a glandular secretion extruded from the spinneret and hardened into a filament on exposure to air. Commercial textile silk comes from various silkworms. The cocooned pupae are killed by steam or hot air, and the cocoons are placed in hot water to soften the gum (sericin) that binds the silk. The filaments from several cocoons are then unwound together to form a single strand of “raw silk,” which is reeled. Several strands are twisted together (thrown) to form yarn. At this stage, or after weaving, the sericin is washed away. The thickness of the yarn is measured in denier. About 70% of all raw silk is produced in Japan.