Cleans dirty grout and most surface stains that make tile grout look dirty. Cleans coffee stains, wax buildup, mildew, dirt buildup, calcium, algae, red clay, and more! Works on sealed or unsealed, sanded or unsanded grout of any color. Can also be used to clean surface stains from driveways, concrete surfaces, floors and toilets from rust, calcium, soot and hard water buildup. DO NOT use directly on the tile.