Hydrostatic Head Setting It Correctly on a Tech Pack
Hydrostatic Head should be written into the tech pack with a value, a tolerance and a method. This removes ambiguity from quotations.
Definition to agree
water pressure a fabric withstands. Working figures for Hydrostatic Head normally sit around 1000-10000 mm depending on use in mainstream production. Note ISO 811 water penetration on the tech pack so nobody tests against an older revision.
Target value
Open the specification at 1000-10000 mm depending on use, adjusted to the end use. Record elastane content alongside Hydrostatic Head, because blends shift the measured value. A result outside 1000-10000 mm depending on use usually points to process drift rather than to the fibre itself.
Method line
Always pair the target with ISO 811 water penetration so the mill and the laboratory test the same way. Keeping reference values for Hydrostatic Head lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 811 water penetration, since both affect the reading.
Tolerance line
State plus or minus limits to keep production realistic while protecting the requirement. Working figures for Hydrostatic Head normally sit around 1000-10000 mm depending on use in mainstream production. Note ISO 811 water penetration 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 Hydrostatic Head, because blends shift the measured value. A result outside 1000-10000 mm depending on use usually points to process drift rather than to the fibre itself.
