The water proof finish could be made from a lot of thing depending on the company .resene ,ruber ,(pu) ,PVC, wax, something like that but usually with synthetic metirial thay stick with a synthetic water proof ing permanent finishes. read more
Yes some spandex is waterpoof. Spandex is a synthetic fiber. It is typically made through one offour processes including melt extrusion, reaction spinning,solution dry spinning, and solution wet spinning. read more