Rust-Oleum Stops Rust Primers provide a sound base for the application of Stops Rust enamels on heavily rusted steel. Primers provide twice the rust prevention than using enamels alone. The use of primers promotes topcoat adhesion and helps prevent chipping, cracking, and peeling. Use of Stops Rust primers eliminates the need for multiple coats of the enamel finish. Not for the use of galvanized steel.