Fabric Bending Stiffness and Drape Testing
category
Fabric bending stiffness and drape testing measures the resistance to deformation under its own weight — properties that determine aesthetic drape (how fabric falls in a garment), handle stiffness perception, and functional performance in technical applications (sail shape, filter element self-support, geotextile handling stiffness). Bending length (BS 3356, ISO 4674-2 cantilever method, Shirley stiffness tester): fabric strip (25 mm × 200 mm) slid horizontally over platform edge, length at which fabric deflects under its own weight to 41.5° angle below horizontal measured in cm — bending length C (cm), flexural rigidity G = W × C³ × 10⁻³ (µN·m) where W = fabric weight g/m². KES-F bending rigidity (Kato Tech KES-FB2): pure bending between two rollers from 0 to ±2.5 cm⁻¹ curvature, measures bending rigidity B (gf·cm²/cm = 10⁻⁴ N·m) and hysteresis 2HB — more complete characterisation than cantilever (captures non-linear bending and recovery). Drape coefficient (BS 5058, Cusick drape meter): circular fabric specimen 30 cm diameter draped over 18 cm support disk, projected shadow traced — DC% = (shadow area − support disk area) / (specimen area − support disk area) × 100: DC 25–40% = very drapey (chiffon, georgette), DC 40–60% = moderate drape, DC 70–90% = stiff (canvas, taffeta). Drape determines garment silhouette — couture designers specify DC range as fabric selection criterion; theatrical costume specifications require DC < 35% for fluid evening wear.
Role
Fabric bending stiffness and drape testing quantifies the mechanical property that most directly determines garment aesthetic appearance — a fabric with correct tensile and tear strength but incorrect drape coefficient produces garments that photograph poorly, fit incorrectly in retail display, and generate consumer aesthetic dissatisfaction even when structurally sound, making drape measurement the quality parameter most sensitive to the subjective design requirements that differentiate fashion textile quality.