Silk Degumming and Weighting
topic
Silk degumming removes sericin protein (20–30% of raw silk weight) using 0.5–1.0% soap or 0.05–0.1% protease enzyme at 85–95°C for 30–60 minutes, yielding soft lustrous fibroin fiber. Historical tin-salt weighting (SnCl₂ at up to 100% owf) is now restricted due to fiber degradation and environmental concerns; modern weighting uses tannin-antimony or polyester grafting to restore handle and drape. Degummed silk has 20–25% higher dye affinity and tensile strength of 3.5–5.0 g/denier. Premium degummed silk adds $5–15/kg to processing cost.
Role
Mandatory first step in silk processing transforming stiff raw silk into soft lustrous fiber suitable for dyeing and weaving, directly determining final fabric quality and luxury market price point.