Flitz Ultimate Crust RemoverPatented, revolutionary, X-strength GEL quickly and easily removes even the crustiest of stains, deposits and build-up. Leaves a water-repellant shield. GEL formula has proven more effective than the competitive products. Since Flitz Ultimate Crust Remover uses organic salt, this product can be used indoors or outdoors. Made of an organic salt, it is safer and easier to use than traditional acid cleaners. Organic salt: 10 times stronger than vinegar.; Safe for use on: Glass, Plastic & Acrylics, Chrome, Aluminum, Fiberglass, Tile, Stainless Steel, Brass, Copper, Painted Surfaces and Enamel Finishes.; Removes: Encrusted Calcium/Lime, Heavy Green Tarnish, Heavy Oxidation, Rust, Corrosion, Oil, Water Stains, Soap Scum Build-Up.; Not Suitable for: Marble, some Granite, Jura, Travertine, & Terrazzo.; How to Use Flitz Ultimate Crust Remover: Spray full strength onto surface; Wait up to 1 minute (do not let dry); Rinse well with water; For severe encrustation, repeat and agitate with a brush.