The customer's request for WP implicitly requires both DWR and WP, for reasons similar to those mentioned in Q3.
The Rain Test in the WP test package is used to "check for leaks and fill gaps":
For example, testing fabric seams, zippers, and other details to see if they leak in the rain (a hydrostatic pressure test may only test the fabric itself, ignoring the seams). However, if the product structure is simple (such as a complete waterproof fabric), a rain test can be omitted; hydrostatic pressure testing alone can suffice to prove waterproofness.
Typical Specifications: 20K/20K:
Waterproof: 20,000 mmH₂O (20 meters of water column) + Breathability: 20,000 g/(m²・24h) (20 kg of water vapor per square meter per 24 hours), suitable for high-intensity outdoor use.
