Hydrostatic Head Frequently Asked Questions
Short answers to the questions buyers ask most often about Hydrostatic Head.
What does it mean?
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.
What value should be specified?
Start from 1000-10000 mm depending on use and adjust for the end use of the garment. 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.
How is it tested?
ISO 811 water penetration. 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.
Why does it change between lots?
Process variables such as finishing temperature and elastane batch cause the normal spread of results. 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.
Can results be compared across suppliers?
Only when the same standard revision and conditioning are used; otherwise measurements are not equivalent. 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.
