Air Permeability Setting It Correctly on a Tech Pack
Air Permeability should be written into the tech pack with a value, a tolerance and a method. This removes ambiguity from quotations.
Definition to agree
volume of air passing through fabric. 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.
Target value
Open the specification at 50-500 mm/s depending on structure, adjusted to the end use. 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.
Method line
Always pair the target with ISO 9237 air permeability so the mill and the laboratory test the same way. 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.
Tolerance line
State plus or minus limits to keep production realistic while protecting the requirement. 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.
Approval step
Approve the result on pre-production bulk rather than on development fabric only. 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.
