Plastic bumpers are so different in composition that one type of paint will work perfectly on one type of plastic bumper, but melt the surface of another plastic bumper. This is due to compositional differences in the types of plastics used to make plastic bumpers. Before investing money in paint, you need to identify the type of plastic used to fabricate your bumper. This will allow you to purchase the correct paint for your painting project and ensure that the paint will not crack away from the surface of the plastic bumper.
Find the three-digit identification code stamped into the back of the plastic bumper. Lookup the three-digit code in the plastic identification manual to determine the type of material you will be painting. Select your paint according to the recommendations of the plastic identification manual.
Place a scouring pad in the bucket of clean water. Add enough dish washing liquid to the bucket of clean water to create lather, but not enough to discolour the water. If you have a large concentration of dish washing soap in the water, it will be difficult to remove the soap residue from the surface of the plastic bumper.
Clean the surface of the plastic bumper with the soapy-water-filled scouring pad to remove the mould releasing agent and other chemicals from the plastic bumper.
Rinse the plastic bumper with clean water. Make sure that no soapy water remains anywhere on the plastic bumper.
Dry the surface of the plastic bumper with a dry towel.
Apply wax, grease and silicone remover to a clean, dry scouring pad and clean the surface of the plastic bumper with the cleaner laden scouring pad. Thoroughly rinse the cleaner from the plastic bumper and repeat steps three and four.
Coat the surface of the cleaned and dried plastic bumper with the plastic adhesion promoter per the promoter application instructions. You will need either an airless or an air-powered paint gun for some applications.
Spray the primer on the surface of the plastic bumper, after the plastic adhesion promoter has dried.
Apply two to three light coats of paint to the plastic bumper after the primer has cured to finish painting the plastic bumper.