Modulus Test Methods and Acceptable Limits
Modulus is verified through ISO 13934-1 modulus. Knowing how the method works avoids rejecting fabric that actually meets the requirement.
Method overview
ISO 13934-1 modulus defines sample size, conditioning and calculation, so values are comparable only within the same revision. Working figures for Modulus normally sit around 4-8 kPa at 30% extension in mainstream production. Note ISO 13934-1 modulus on the tech pack so nobody tests against an older revision.
Result interpretation
Read the value together with construction notes; 4-8 kPa at 30% extension is only meaningful for similar fabrics. Record elastane content alongside Modulus, because blends shift the measured value. A result outside 4-8 kPa at 30% extension usually points to process drift rather than to the fibre itself.
Typical limits
Buyers commonly write 4-8 kPa at 30% extension with a stated tolerance, then verify against ISO 13934-1 modulus. Keeping reference values for Modulus lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 13934-1 modulus, since both affect the reading.
Sources of variation
Conditioning time, operator technique and shade all influence the result. Working figures for Modulus normally sit around 4-8 kPa at 30% extension in mainstream production. Note ISO 13934-1 modulus 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 Modulus, because blends shift the measured value. A result outside 4-8 kPa at 30% extension usually points to process drift rather than to the fibre itself.
