GSM Test Methods and Acceptable Limits
GSM is verified through ISO 3801 fabric mass. Knowing how the method works avoids rejecting fabric that actually meets the requirement.
Method overview
ISO 3801 fabric mass defines sample size, conditioning and calculation, so values are comparable only within the same revision. Working figures for GSM normally sit around 140-320 GSM for activewear in mainstream production. Note ISO 3801 fabric mass on the tech pack so nobody tests against an older revision.
Result interpretation
Read the value together with construction notes; 140-320 GSM for activewear is only meaningful for similar fabrics. Record elastane content alongside GSM, because blends shift the measured value. A result outside 140-320 GSM for activewear usually points to process drift rather than to the fibre itself.
Typical limits
Buyers commonly write 140-320 GSM for activewear with a stated tolerance, then verify against ISO 3801 fabric mass. Keeping reference values for GSM lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 3801 fabric mass, since both affect the reading.
Sources of variation
Conditioning time, operator technique and shade all influence the result. Working figures for GSM normally sit around 140-320 GSM for activewear in mainstream production. Note ISO 3801 fabric mass 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 GSM, because blends shift the measured value. A result outside 140-320 GSM for activewear usually points to process drift rather than to the fibre itself.
