What Is the Hydrostatic Head Test and Why Does It Matter for Buyers?
What Is the Hydrostatic Head Test and Why Does It Matter for Buyers? The hydrostatic head test measures how much water pressure a fabric can withstand before water penetrates through it, expressed in millimeters (mm) of water column. In simple terms, it answers one question: how much rain can your jacket handle before you feel wet? For buyers sourcing waterproof fabrics, this single number separates a reliable shell from a marketing claim. This article explains the test procedure, industry standards, what the numbers actually mean in real-world conditions, and how to use hydrostatic head ratings when evaluating suppliers. Relevant specifications and application guidance are available through Fabric products . Key Takeaways Hydrostatic head (HH) is measured in millimeters of water column; higher values mean better waterproofing. Industry standards like ISO 811 and AATCC 127 define the test procedure, but results vary with fabric construction and finishing. A rating of 1,500 mm is...