Krud Kutter Rust, Calcium & Lime Stain Remover attacks built up rust stains and mineral deposits with a safe, effective cleaner. Apply on showers, showerheads, sinks, glass, plastic, vinyl, aluminum, concrete driveways, wood decks, stone, masonry, tubs, toilets, porcelain, fiberglass, wood & steel siding, sidewalks & patios, brick, stucco and more. Heavy stains may require an additional application.