GSM How It Changes with Construction and Elastane Content
GSM does not stay constant when construction changes. Understanding the direction of change helps during development.
Effect of knit structure
Loop length and density move results first, usually before any yarn change is made. 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.
Effect of elastane content
More elastane raises recovery but changes the value measured by ISO 3801 fabric mass, so retest after any blending change. 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.
Effect of finishing
Heat setting and softeners shift results, which explains differences between a hand sample and bulk. 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.
Typical range
Working values stay around 140-320 GSM for activewear for mainstream activewear. 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.
Development advice
Change one variable at a time, then verify against ISO 3801 fabric mass before moving to the next sample round. 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.
