^^^^ Is it actually though?(genuine question) I know most waterproof fabrics work fine in tension like that, but the problem comes when it has something pressing against the inside of the membrane, which might be an issue with a close fitting jacket,
and, its not airtight, so it's going to let air through under pressure, not sure how that relates to normal usage
^ dry shampoo?
^^^^ Is it actually though?(genuine question) I know most waterproof fabrics work fine in tension like that, but the problem comes when it has something pressing against the inside of the membrane, which might be an issue with a close fitting jacket,
and, its not airtight, so it's going to let air through under pressure, not sure how that relates to normal usage