(1) Any film-forming substance that coats a substrate with a water-repellent layer, such as paint, a rubber or plastic film, a wax, or an asphaltic compound. These are used on a wide variety of surfaces, including cement, masonry, metals, textiles, etc.(2) Any metal salt or other chemical that impregnates textile fibers in such a way as to give an air-permeable, water-resistant product. There are three types of these: renewable, semidurable, and durable. Renewable repellents are water dispersions containing aluminum acetate or formate, emulsifying agents and protective colloids in the continuous phase, and a blend of waxes in the disperse phase. Semidurable repellents involve precipitation of insoluble metal salts on the fibers; water-soluble soaps and waxes are usually added to the mixture, which is especially effective on synthetic fibers. Durable repellents coat each fiber with a protective film without bonding them together or sealing the apertures.