Silk Fibre Testing

Silk fibre testing characterises reelability, filament fineness, raw silk grade, degumming loss, tensile properties, and lustre of Bombyx mori cultivated silk and wild silk (tussah, eri, muga) used for luxury textile production. Raw silk quality is graded by the International Silk Association (ISA) and JISFA (Japan Silk Foundation) standards measuring: reelability (% cocoons successfully reeled at standard conditions, optimum >85%), filament linear density (denier of raw silk from standard 8-end or 10-end reeling, Mulberry raw silk 14–30 denier, 1 denier = 1 g / 9,000 m), size variation (CV% of reeled filament along length, Grade 3A: <2.5%), neatness (defects per 100 m: loops, frizz, double ends, snarls — Grade 3A: <100/100m), cleanliness (stains and contamination rating), and gum content (sericin 20–30% of raw silk weight). Degumming loss (ISO 6940 adapted, NaOH 2 g/L, 95°C, 30 min — degummed silk = fibroin core, sericin removed) is commercially critical: buyers pay per degummed weight basis — 1 kg raw silk yields 700–800 g degummed fibroin at $35–80/kg fibroin versus $18–35/kg raw silk price. Single fibre tensile testing (Textechno Favimat+, 20 mm gauge, 0.1 cN/tex pretension): Bombyx mori single filament tenacity 35–50 cN/tex, elongation 15–25%, modulus 5–12 GPa — properties degraded by sericin retention (>5% sericin remaining) or photodegradation (UV exposure >50 kJ/m² causes 30–50% strength loss).