Removes and prevents rust in 1 step. Removes hard water, calcium, and lime deposits. Water-based formulation penetrates into every void of a metal surface and dissolves rust and oxidation through chemical action. When dry, Must For Rust accepts any primer, paint, coating, plating, welding, etc. Provides a clean surface free of contaminants. Safe, fast, effective on rusted or new metals, chrome, brick, concrete, stucco, fiberglass, porcelain, ceramic, and glass. Not for use on marble. Covers 500 sq. ft. per gallon.