Rust-Oleum Galvanizing Compound A21-8500 Rust-OleumGalvanizing Compound A21-8500 A zinc-rich primer containing 95% metallic zinc in the dry film which provides maximum corrosion resistance through galvanic protection. Comply with ASTM A 780 Use to touch-up sheet metal, production welds, galvanized ducts, storage tanks, fences, gutters, trucks, trailers, off-shore oil rigs and utility towers. APPEARANCE : Dull silver metallic RECOMMENDED TOPCOATS : 470 Aluminum, 473 Heavy Duty Aluminum COMPATIBLE TOPCOATS : 5200 System Finishes, Epoxy, Polyurethane