Getting great painting results is always dependent on the preparation work beforehand. This is especially true for painting plastic hubcaps. Auto spray paint is best for a professional-looking finish because there is a wide range of paints made just for automotive plastics. Also, spray paint is easy to use and, when done properly, the finished result looks great.
Wash the plastic hubcaps thoroughly with dish detergent and hot water. Dish detergent is perfect for automotive use because it is gentle and it acts as a degreaser. Let the hubcaps thoroughly dry and remove them from the tires using a flathead screwdriver if they need a little prying.
Sand over any scratches or surface damage first with 320-grit sandpaper in gentle circular strokes, then follow up with 600-grit sandpaper. Sand only the damaged areas. Next, wet-sand the scratches with 1000- to 1500-grit sandpaper. Dip the sandpaper in clear water and sand in circular strokes. Keep the area wet by squeezing a wet towel over the surface while sanding. If the plastic is brand new, lightly scuff the plastic surface with a red scuff pad.
Shake the can of primer vigorously and spray a light coating over the surface. The primer promotes paint adhesion and fills in leftover scratches from sanding or scuffing. Allow the primer to dry for 10 minutes and apply another coat. Let the primer dry for 30 minutes and wet-sand the entire surface with 1000- to 1500-grit sandpaper. Apply two more coats of primer, and wet sand again after each coat.
Shake the can of spray paint and apply a thin coat of paint. Let dry for two hours and apply another thin coat. Each coat should look uniform. Apply as many coats as necessary to reach the desired darkness. Let dry 30 minutes before applying clear coat.
Shake the clear coat vigorously and spray four coats, letting each application dry thoroughly before spraying the next coat. Let the clear coat dry for one day and apply rubbing compound to bring out the gloss. Wait 30 days before waxing the hubcaps.
Spraying multiple thin coats will result in a superior finish rather than a single heavy coat.
Avoid spraying paint in direct sunlight and in high humidity. The optimum ambient temperature for spray painting is 21 to 26 degrees C (70 to 80 degrees F.).