Waterproof fabrics are fabrics that are inherently, or have been treated to become, resistant to penetration by water and wetting. The term “waterproof” refers to conformance to a governing specification and specific conditions of a laboratory test method. They are usually natural or synthetic fabrics that are laminated to or coated with a waterproofing material such as rubber, polyvinyl chloride (PVC), polyurethane (PU), silicone elastomer, fluoropolymers, and wax. Examples include the rubberised fabric used in Mackintosh jackets, sauna suits and inflatable boats. They are even used for footballs and glasses.