Rust-Oleum® Stops Rust® Primers provide a sound base for 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 enamel finish. Not for use of galvanized steel.