Urethane plastic is a polymer consisting of organic units joined by carbamate links. The main problem with painting urethane plastic centers around the fact that it is nonporous. Any nonporous surface lacks the ability to adequately absorb paint adhesives. This typically results in an unstable finish that ultimately flakes and peels. Professionals abrade urethanes to improve their adhesive qualities. If you want a durable, lasting finish, employ this same technique.
Things You'll Need
Coarse nylon pad
Canvas drop cloth
150- to 180-grit sandpaper
Wash the urethane plastic with water-based soap, using a coarse nylon pad. Rinse the urethane with wet rags. Place it on a canvas drop cloth and allow it to dry for about an hour.
Abrade the urethane plastic to improve its adhesive qualities. Sand the urethane until it feels rough. Use 150- to 180-grit sandpaper.
Wipe the plastic with a rag dampened with mineral spirits. Allow 10 minutes for the solvent to evaporate.
Coat the urethane plastic with latex primer, using a polyester paintbrush. This particular type of brush produces smoother results. Don't use a brush that has nylon bristles. Let the urethane dry for two hours. Wash the brush, using plain tap water.
Sand the primer base, using 320-grit sandpaper. Stop when the base feels slightly rough or tacky.
Wipe the plastic with a tack cloth.
Paint the urethane plastic with an acrylic enamel, using a polyester brush. Let the urethane dry for two hours.
Sanding is critical to promoting adhesion. If you prime unsanded urethane plastic, flaking will follow. Likewise, if you apply paint directly over an unsanded primer base, the paint may not properly adhere.