Clean and prep concrete, stone, brick, tile and galvanized metal with RUST-OLEUM Zinsser WATERTITE etch and cleaner for concrete and masonry. This solution quickly restores a stain-free surface and also preps it for painting, patching or waterproofing. Prepares concrete for waterproofing and painting Removes efflorescence, fast and effective Safer than muriatic acid Use on interior and exterior concrete and masonry surfaces.