Fabric Elongation and Elastic Recovery Testing

Fabric elongation and elastic recovery testing measures the extensibility and shape-retention capacity of stretch woven, knitted, and elastane-blend fabrics critical for activewear, swimwear, compression garments, and form-fitting apparel. Elongation at specified force (ISO 14704-1, strip method, elongation measured at defined reference load — 20 N for lightweight stretch, 50 N for swimwear, 100 N for compression fabric, 500 mm gauge): stretch woven (3–5% elastane, 2-way stretch) elongation 40–80% at 50 N; 4-way stretch (warp + weft elastane, 8–12%) elongation 80–150% at 50 N; compression fabric (18–22% elastane, circular knit) elongation 80–120% at 20 N per ASTM D2594. Elastic recovery testing (ISO 4919, SDL Atlas M300, 10 extension-recovery cycles to specified elongation — 20%, 40%, or 80% depending on application — at 100 mm/min extension and 100 mm/min return): recovery% = (extension − permanent set after 60 sec relaxation) / extension × 100. Specification minimums: swimwear elastic recovery ≥ 90% at 80% elongation (ISO 4919), after 300 hours chlorine exposure (100 ppm, pH 7.5); activewear ≥ 85% at 40% elongation after 20 wash cycles (ISO 6330 40°C); medical compression hosiery ≥ 92% recovery at 40% elongation. Growth test (ASTM D3107, fabric extended to 60% elongation, held 30 min, recovery measured after 30 min rest — growth% = permanent set / original length × 100): growth <5% acceptable for standard stretch apparel, <3% for premium activewear. Power (holding force at specified elongation, cN/cm width) determines compression garment therapeutic pressure: RAL-GZ 387 Class 2 compression stocking requires 23–32 mmHg at ankle — calculated from fabric power measurement at anatomical circumference extension.