Painting on Sheet Metal

Preparing Metal for Painting

• Prepare an old galvanized sheet metal for painting by taking fine sandpaper or a wire brush to the surface to be painted. Remove the white rust created by the zinc over time, reducing the metal as little as possible. The fine sandpaper or wire brush will also roughen the finish of the metal slightly, which will keep the paint from peeling or flaking off later. Wipe off the sandpaper or wire remains from the metal using white vinegar on a damp cloth. New sheet metal will not have a white rust problem, and should be cleaned with a water-based cleaner in order to remove dirt and oil. Roughen it for painting purposes by dampening a cloth with white vinegar, which will etch the metal slightly to encourage paint adherence.

Primer

• For galvanized metal, use a primer made specifically for it. A good exterior multipurpose primer made of latex works for other sheet metals to be painted. Avoid primers with built-in etching if you prepared the sheet metal earlier for painting. Wipe down the sheet metal with a diluted portion of white vinegar on a clean cloth after applying the primer.

Painting Options

• Sheet metal used in outdoor structures requires a paint that can stand up to the elements over time. Exterior latex house paint is a good option. The higher the quality, the greater the likelihood the paint will withstand temperature extremes. If your sheet metal will be used for indoor art purposes, a greater diversity of paint options is available, including oils and acrylics. Any type of brush is suitable for painting on sheet metal. Allow to dry before adding the top coat.

Top Coat

• Any portions of the sheet metal that were not painted should still be coated with a clear protective top coat over the metal, such as clear gesso -- a combination of glue, pigment and filler, which can be purchased premixed. The painted portions of your sheet metal should be covered with two coats of a good exterior latex paint if the painted sheet metal was used for an outdoor home addition. For art use, coat the painted metal with epoxy.