Metal surfaces are often coated with a zinc plating that protects them from rust. Unfortunately, this layer is ill-suited for adhesion and will reject painted finishes if it is inadequately or improperly prepared. If you want to paint zinc-plated metal, pretreat it with a primer, specifically formulated with acidic qualities that allow it to etch durable zinc plated metallic surfaces. Apply the base and finish coats, using the proper brush, or the finish may dry marred with brush marks.
Wash the zinc-plated metal with a water-based, degreasing cleanser, using steel wool. Rinse exterior metal with a hose. Use wet rags to rinse indoor metal. Allow the zinc plating to dry for two to three hours.
Coat the zinc-plated metal with galvanised metal etching primer, using a roller and a shed-free roller cover. Roll one three-by-three foot section at a time. Stop and smooth the wet etching primer, using a polyester paintbrush. Brush vertically, applying slight pressure. Allow the zinc plating to dry for three hours.
Wash the galvanised metal etching primer from the brush, using plain tap water.
Coat the primed zinc-plated metal with acrylic enamel, using the roller and a clean shed-free cover. Roll one three-by-three foot section at a time. Stop and smooth the wet enamel, using the polyester brush. Brush vertically, applying slight pressure. Allow the zinc plating to dry for three hours.
Never paint unprimed zinc-plated metal, or the paint will peel. Do not use latex, oil or acrylic primer on zinc-plated metal, or the finish will flake. Do not prime or paint zinc-plated metal, using a nylon paintbrush, as this will mar the finish will brush marks.