But that’s what he’s testing - what happens when you sit on a wet seat or kneel on wet ground or have your feet pushed into wet boots. That’s what you need GoreTex for. It’s a stress test. They’re already trivially waterproof when just sitting there that’s obvious so no need to test it.
But the rig he made was meant to simulate the actual test of having a long thin tube of water sitting over a tiny section of the fabric. It introduces a lot more widespread stretching than the real test would, inflating the fabric like a balloon (not just simply applying pressure). I bet this affects the water resistance of the fabrics quite a lot, beyond what you'd normally apply to it. Do you stretch your knee fabric like a balloon when you apply pressure onto it to the ground?
> Do you stretch your knee fabric like a balloon when you apply pressure onto it to the ground?
When you kneel? Yeah it can be subject to a lot of stress as it's drawn taught over your knee. And if you had a heavy pack on it could be taking 150 kg.
If all you do in your Gore-Tex is stand still in the rain it's probably not a valid test - if you're using it for outdoors work then it is.
What he is testing is exactly what a column of water would do in a standard test. Re-watch the beginning and he talked about how to test it without the pump they would need at least a 92 foot long pipe. That would be 1,104 cubic inches of water, or 4.8 gallons of water, or about 40 lb, which would be 40 psi in the standard test. He is simply replicating the industry standard test that the manufacturers claim. You could argue that the test is flawed but literally every manufacturer uses it and I guarantee that 40 lb pushing down on a 1” by 1” square of fabric will stretch it.
In a standard test machine you clamp the material in such a a way as to not introduce deformities in the fabric.
I.e. the whole piece should start out flat, his test setup has it clamped around the end of a pipe. You can see in the video how some of the leaks and tears start at the stress points where the fabric is folded near the opening of the pipe.
It's meaningless to make any general assumptions about how such a non-standard test setup relates to how a fabric would perform in the standard test.
