There are three relevant waterproof standards: GB/T 4744-2013 "Textiles — Determination of Water Resistance — Hydrostatic Pressure Test," GB/T 4745-2012 "Textiles — Determination of Water Resistance — Spray Test," and GB/T 21295-2014 "Technical Requirements for Physicochemical Properties of Apparel."
Test Item One: Hydrostatic Pressure
1. According to GB/T 4744-2013 "Textiles — Determination of Water Resistance — Hydrostatic Pressure Test," the hydrostatic pressure value is expressed in KPa/cmH2O. The higher the test result, the greater the hydrostatic pressure the fabric can withstand, indicating better waterproof performance.
2. GB/T 21295-2014 "Technical Requirements for Physicochemical Properties of Apparel" links products with rainproof functions to water pressure, stipulating that “finished products requiring rainproof functionality must have a hydrostatic pressure resistance of no less than 13KPa, and those requiring heavy rainproof functionality must have a resistance of no less than 35KPa.”
With these two standards referenced, and with this concept in mind, you’ll now surely be able to relate them to your actual needs.
Test Item Two: Surface Water Repellency
1. Tested according to GB/T 4745-2012 "Textiles — Determination of Water Resistance — Spray Test," the fabric’s water spray rating is evaluated to assess its waterproof performance. The image below captures the testing process — doesn’t it resemble dewdrops rolling off a lotus leaf?
