Used by professionals to restore a new appearance to dirty, discolored limestone, poured concrete, walkways, precast or poured aggregate, travertine, and more. It contains no hydrofluoric acid, cleans without leaving yellow stains, and will not etch glass. This product will safely remove atmospheric dirt, mildew, rust, and many other surface stains without risk of bleaching or discoloration. It also works well to remove rust and oxidation from aluminum.