Paint Over Powder Coating
Q. Can I paint over powder coating? Will the paint adhere? One
of our customers supplies coated aluminum castings to a small appliance manufacturer.
He has a number of aluminum housings painted with a white polyester powder
coating. Now the manufacturer wants castings in other colors. G.W
A. Paints will adhere to powder coatings, providing there is
no slip agent present on the surface. Slip agents are often formulated into
powder coatings to increase their mar resistance. Your customer’s powder
supplier will tell you whether a slip agent is used in his powder. If the slip
agent is present on the powder coating’s surface, it must be removed
before painting by solvent wiping or sanding. If this procedure does not remove
the slip agent, the castings must be stripped to bare metal.
After the appliance castings are prepared for recoating, I suggest using a polyester,
thermosetting acrylic or polyurethane enamel to achieve the same high quality.
