Twist Testing Methods
topic
Twist is measured by: (1) untwist-retwist method (ISO 2061): yarn is untwisted then re-twisted to original length, counting turns; (2) direct counting under microscope for fine yarns. Test length 25–50 cm; minimum 20 tests per sample. CVtwist% <5% is standard specification. Automated twist testers (e.g. Uster Twist Tester 5) measure 100+ tests per hour. Skein twist tester measures twist in doubled yarns. Twist direction verified by visual inspection of helix under ×10 lens.
Role
Twist testing is mandatory for quality release of yarn sold to weaving and knitting customers because twist level directly determines fabric handle, strength, and appearance. Supplying yarn with incorrect twist — even within the count and evenness specification — causes fabric faults that are only discovered after the entire lot is woven or knitted, resulting in claims that are the spinner's responsibility.