Seam Strength How It Changes with Construction and Elastane Content
Seam Strength 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 Seam Strength normally sit around above 100 N specification in mainstream production. Note ISO 13935-2 grab method 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 13935-2 grab method, so retest after any blending change. Record elastane content alongside Seam Strength, because blends shift the measured value. A result outside above 100 N specification 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 Seam Strength lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 13935-2 grab method, since both affect the reading.
Typical range
Working values stay around above 100 N specification for mainstream activewear. Working figures for Seam Strength normally sit around above 100 N specification in mainstream production. Note ISO 13935-2 grab method on the tech pack so nobody tests against an older revision.
Development advice
Change one variable at a time, then verify against ISO 13935-2 grab method before moving to the next sample round. Record elastane content alongside Seam Strength, because blends shift the measured value. A result outside above 100 N specification usually points to process drift rather than to the fibre itself.
