Natural Marine Boat Top Waterproofing is a premier quality water-based fluorochemical that repels water and oil on natural and synthetic fibers. UV screen protects threads. Helps prevent mildew stains in storage. Safe for boat covers, bimini tops, tents,awnings, clothing, dodgers, and sails. Concentrated formula with industry leading 12% silicone. Even if you can see through the fabric, this will waterproof it. 1 bottle treats up to 36 sq. ft.