If your deck has been previously treated with a clear waterproofer or a transparent or semi-transparent deck stain, you're going to need a little extra muscle. Thompson's® WaterSeal® Heavy Duty Deck Cleaner has the power to restore the natural color to severely discolored wood without bleaching. Apply and in minutes you can scrub and rinse away old finishes. If you want to remove solid stains, you'll need to use Thompson's® WaterSeal® Maximum Strength Deck Stripper. This fast-acting formula will also take off difficult to remove transparent and semi-transparent deck stains, and clear waterproofers, while cleaning stains from dirt, mildew, algae and fungus. Read the label directions thoroughly before using products.