Rusting occurs when metal is exposed to moisture and oxygen. Any metal surfaces should be completely sealed with a rust inhibited primer. If rust appears through painted surfaces, it should be wire brushed to bare metal, or treated with a coating that will harden it. Two coats of a top quality rust inhibited alkyd or acrylic latex primer should be applied to metal surfaces once the rust is treated or wire brushed away. Rusty nails that bleed through surfaces should be reset, coated with a top quality rust inhibited primer, caulked, primed, and painted with top quality coatings.