Removes Severe hard water stains that have been there for up to 30 years with well water/ very hard water. Biodegradable, used in hospitals, institutions, public & commercial facilities, as well as many homes across the world. Hard Water Stain Remover removes all calcium and mineral deposits, rust, tree sap, paint overspray, mildew, mold, hair dye & food coloring stains. Multi-surface Hard Water Stain remover works great on: Shower doors, tile, chrome, porcelain, fiberglass, stainless steel, aluminum, brass- all glass, metal and stone surfaces. Completely restoring the surface back to its original condition. Plus has a sealant in the product that will seal the area for up to 3 months, to prevent stains from forming.