In theory, painting is easy. You choose a color, purchase some paint, put it in a bucket and use a brush to apply it to the chosen surface. However, every type of painting requires special considerations specific to the job, including choosing the right paints and primers. When painting over powder coating, for instance, you must use special types of primers and paints designed specifically to work together.
Powder coating consists of exactly what it sounds like, a coating material made of powder. The chemical and automobile industries developed powder coating in response to United States government emissions standards placed on solvents commonly found in paints. Powder coating constitutes an alternative coating to paint, commonly found as an exterior layer on items with steel or aluminum cores. As a surfacing material, powder coating provides a corrosion-resistant layer over metals as a means of protecting them from rust and other environmental wear.
Painting Over Powder Coating
Painting over powder coating requires a few special considerations before you begin applying primer. Even if you purchase the perfect primer for painting over powder coating, the primer may not stick if you fail to properly prepare the powder-coated surface beforehand. Remove dirt, minerals, debris, chalky residue and any other filth built up on the surface of the powder coating using an abrasive nylon pad. Once clean and dry, use a power stander to scuff sand your powder coating to a dull sheen. This process keeps the corrosion resistance of the powder coating intact but provides flat, even surface for painting.
Paints and Coatings Resource Center, an online painting reference, recommends using any two-component epoxy primer over scuff-sanded powder coatings. Use a two-component polyurethane or single-component acrylic topcoat over this paint. Because all of these elements contain toxic chemicals, you can use a complete acrylic latex system instead. This consists of a specific set of acrylic latex primers and paints designed to work together. You can find these materials at a hardware store or online.
Various brands produce paint and primers designed for use over specific materials, such as galvanized steel, coil coatings and powder coatings. For instance, Dulux, a protective coating manufacturer, produces a line of paints called Weathermax HBR designed for use with powder coil coating. Dulux recommends using Luxepoxy 4 White Primer for use with Weathermax HBR when painting powder coating over an aluminum surface and Durebild STE primer when painting powder coating over a steel surface.