Air Permeability How It Changes with Construction and Elastane Content
Air Permeability 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 Air Permeability normally sit around 50-500 mm/s depending on structure in mainstream production. Note ISO 9237 air permeability 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 9237 air permeability, so retest after any blending change. Record elastane content alongside Air Permeability, because blends shift the measured value. A result outside 50-500 mm/s depending on structure 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 Air Permeability lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 9237 air permeability, since both affect the reading.
Typical range
Working values stay around 50-500 mm/s depending on structure for mainstream activewear. Working figures for Air Permeability normally sit around 50-500 mm/s depending on structure in mainstream production. Note ISO 9237 air permeability on the tech pack so nobody tests against an older revision.
Development advice
Change one variable at a time, then verify against ISO 9237 air permeability before moving to the next sample round. Record elastane content alongside Air Permeability, because blends shift the measured value. A result outside 50-500 mm/s depending on structure usually points to process drift rather than to the fibre itself.
