Paint metal surfaces with anti-rust enamel or multipurpose enamel paint, followed by an anti-rust enamel top coat. Bare metal surfaces should be free of rust, dirt and grease before priming and painting.
Wash new galvanized metal with warm soapy water to remove the oily residue and sand old galvanized metal to remove oxidization before priming. For ferrous metal, use a wire brush to remove any rust, and wipe clean with a damp cloth. Wipe the surface with vinegar and a clean, soft cloth to abrade the metal. Once dry, prime immediately with a metal primer to retard flash rust growth. Paint according to enamel instructions.