Rust remover containing phosphoric acid and surfactants: Primarily suitable for iron and steel, with limited suitability for other metals and completely unsuitable for some metals. Primarily used for rust removal and most effective in conjunction with hand scrubbing. A viable chemical alternative to abrasive rust removal. (i.e., sandpaper, steel wool, and sand and soda blasting.) Properly applied, it provides a significant degree of corrosion resistance, in the form of a thin layer of iron phosphate on the substrate. Also suitable for paint prep, mildly etching the surface and the iron phosphate residue acts as a type of primer.
Initially, I used Must for Rust and subsequently switched to PPG DX579. (I've since switched to using electrolytic rust/paint removal tanks, followed by brief DX579 treatment.)
Back when I was using Must for Rust, I sandblasted a pair of stamped steel engine mounting brackets. I treated one with Must for Rust and left the other untreated. After two years in an open unheated shed in interior Alaska, the treated bracket was just starting to show a slight orange tinge, indicating the initial stage of surface rust. (A quick wipe down with Must for Rust brought it back to ready-to-paint condition.) The other bracket was exhibiting significant surface rust, requiring a complete repetition of the rust removal and treatment process.
