Modulus How It Changes with Construction and Elastane Content
Modulus 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 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.
Effect of elastane content
More elastane raises recovery but changes the value measured by ISO 13934-1 modulus, so retest after any blending change. 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.
Effect of finishing
Heat setting and softeners shift results, which explains differences between a hand sample and bulk. 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.
Typical range
Working values stay around 4-8 kPa at 30% extension for mainstream activewear. 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.
Development advice
Change one variable at a time, then verify against ISO 13934-1 modulus before moving to the next sample round. 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.
