Fabric Drape Coefficient Testing
topic
Fabric drape coefficient (DC%) is measured by the Cusick drape meter (BS 5058, SDL Atlas Cusick Drapemeter) or automated digital drape meter (Kato Tech KES-F drape, Lenzing Instruments DDM): a circular fabric specimen (30 cm diameter for Cusick standard; 36 cm for ASTM D4848) is placed horizontally over a smaller circular support disk (18 cm diameter, 12.7 cm for ASTM) and illuminated from above — the unsupported annular ring falls into 4–8 fabric folds (drape nodes), and the projected shadow area measured by planimetry (manual tracing and weighing paper, or digital camera + image analysis software). DC% = (S − Ss) / (Sf − Ss) × 100 where S = shadow area, Ss = support disk area (254 cm²), Sf = specimen area (707 cm²) — low DC = drapeable, high DC = stiff. Node count (number of drape folds) and node regularity also characterised: fabric with 5–7 regular nodes and DC 40–50% ideal for structured garments; fabric with 4 irregular nodes and DC 35% is less controllable in drape direction (unpredictable fold placement in garment making). Anisotropy of drape (separate warp versus weft bending measurement): balanced woven fabric DC = 45% both directions (uniform circular shadow); anisotropic (satin weave) DC warp = 35%, weft = 60% (asymmetric shadow — produces directional draping preferred for evening gowns). Dynamic drape (fabric oscillated vertically ±50 mm at 1 Hz during measurement) reduces DC 5–15% for heavy fabrics (momentum enhances folding) — dynamic drape better represents drape in walking movement. KES-F drape correlation with consumer preference: fabrics with KES-F DC 38–52% receive highest drape preference ratings in consumer panel studies for women's woven dresses.
Role
Drape coefficient testing is the objective measurement of the aesthetic fabric behaviour that most directly determines garment appearance and consumer appeal — design specifications for drape coefficient enable fashion designers to select fabrics that will produce intended garment silhouettes in mass production rather than relying on subjective hand evaluation that varies between technicians, making DC measurement essential for scaling artisanal design intent into reproducible manufacturing quality specifications.