Yarn Count Variation and Between-Package Testing

Yarn count variation testing measures count consistency within a package (within-package CV%), between packages in a lot (between-package CV%), and between lots (lot-to-lot CV%) — three levels of variation that cause fabric weight unevenness, dye shade variation, and weaving or knitting tension problems at different spatial scales. Within-package count variation (10 skeins × 100 m from single package, CV% < 1.5% for ring-spun warp quality, < 2.5% for knitting quality) is measured by standard ISO 2060 gravimetric protocol — high within-package CV% indicates drafting autoleveller malfunction, uneven card web, or damaged roving bobbin. Between-package count variation (10 packages randomly sampled from lot, 1 skein × 100 m per package, CV% < 2.0% for warp yarn, < 3.0% for knitting) — between-package CV% > 3% causes shade variation in fabric dyeing because count differences of ±4% produce surface area per unit length differences of ±8% creating visible dye depth variation (metamerism risk). Uster Classimat 5 long-term count measurement (continuous 100,000 m test, count profile every 100 m by capacitive signal integration, CV% of 100 m cut lengths) detects: mean count shift between bobbins (ring frame creel change visible as step change in count profile), periodic count variation with periodicity equal to drafting system wavelengths (roving frame bobbin circumference 0.8–1.2 m, ring frame roving bobbin circumference 0.5–0.7 m), and gradual count drift from bobbin build. Colour-coded count report (Uster Tester 6): count below mean (thin, light colours in fabric), count above mean (thick, dark colours) — visual representation enabling rapid identification of count variation pattern and machine diagnosis.