Yarn Count and Linear Density Testing

Yarn count testing determines the linear density of spun and filament yarns expressed in direct (tex, dtex, denier — mass per unit length) or indirect (Ne cotton count, Nm metric count — length per unit mass) systems, providing the fundamental specification parameter for all yarn commercial transactions and downstream process calculations. ISO 2060 gravimetric method: weigh yarn samples of precisely measured length (100 m for staple yarn, 1,000 m for filament per ISO 7211-5 reel length standard) at standard atmosphere (20°C ±2, 65% RH ±4, ISO 139) — tex = mass in grams × 1,000 / length in metres; Ne = 590.5 / tex (cotton system); Nm = 1,000 / tex (metric system). Measurement accuracy: ±1% for 10 replicate 100 m samples at correct atmospheric conditioning — below-standard conditioning (RH < 60% for cotton yarn) causes moisture loss increasing apparent count by 1.5–3.0% (cotton moisture regain 8.5% standard versus 5.5% at 50% RH). Reel machines (SDL Atlas, Zweigle, 1.5 m or 1.0 m perimeter reels, precision ±0.1 mm perimeter, electronic revolution counter) and laboratory balances (Mettler Toledo XP205, ±0.01 mg) provide equipment for count testing. Uster Tester 6 provides online count measurement during evenness testing by integrating capacitive signal over test length — fast method (1 min test at 400 m/min) but accuracy ±2% versus ±0.5% for gravimetric. Count tolerance in commercial yarn: ring spun Ne 30 ±3% (±0.9 Ne), filament PET 167 dtex ±2% (±3.3 dtex) — out-of-tolerance count causes fabric weight variation and dye shade inconsistency in downstream production.