Skewing and Spirality Test Methods and Acceptable Limits
Skewing and Spirality is verified through AATCC 179 skewness. Knowing how the method works avoids rejecting fabric that actually meets the requirement.
Method overview
AATCC 179 skewness defines sample size, conditioning and calculation, so values are comparable only within the same revision. Working figures for Skewing and Spirality normally sit around below 3% displacement in mainstream production. Note AATCC 179 skewness on the tech pack so nobody tests against an older revision.
Result interpretation
Read the value together with construction notes; below 3% displacement is only meaningful for similar fabrics. Record elastane content alongside Skewing and Spirality, because blends shift the measured value. A result outside below 3% displacement usually points to process drift rather than to the fibre itself.
Typical limits
Buyers commonly write below 3% displacement with a stated tolerance, then verify against AATCC 179 skewness. Keeping reference values for Skewing and Spirality lets suppliers quote without extra sampling rounds. Ask for conditioning details together with AATCC 179 skewness, since both affect the reading.
Sources of variation
Conditioning time, operator technique and shade all influence the result. Working figures for Skewing and Spirality normally sit around below 3% displacement in mainstream production. Note AATCC 179 skewness on the tech pack so nobody tests against an older revision.
Documentation
Record the standard revision on every report, because older versions can differ from current practice. Record elastane content alongside Skewing and Spirality, because blends shift the measured value. A result outside below 3% displacement usually points to process drift rather than to the fibre itself.
