Prepare weathered exterior wood for waterproofing or staining with Thompson's WaterSeal Heavy Duty Deck Cleaner. This heavy-duty formula removes weathered clear and tinted waterproofers. It also removes semi-transparent stains from decks and other exterior wood surfaces. The cleaner targets stains caused by dirt, mildew, algae, and fungus. It restores the natural color of severely weathered and discolored wood without bleaching. The ready-to-use formula requires no mixing before application. Its self-neutralizing formula eliminates the need to apply a separate neutralizing solution. Use it on decks, fences, outdoor furniture, and other compatible exterior wood. The cleaner is also suitable for composite decking. Apply the formula before waterproofing or staining as part of the surface preparation process.