After a bumper is repaired, it needs to be resprayed with bumper paint to restore its original finish. But bumper paint is not the only thing applied to the bumper to give it a long-lasting colour and shine. It must be sealed and primed before any paint is applied. The correct bumper paint, along with the other materials required, can be found at most auto parts stores.
Wash the bumper with a car degreaser to remove any built-up grease and grime. Scrub well and then rinse. If the water does not bead up on the bumper, it needs more cleaning, until water beads form. Let the bumper dry completely before moving on to the next step.
Sand the entire front side of the bumper with 80-grit sandpaper. This will remove any previous finish to prepare the bumper for its new finish. Clean all the sanding dust off by spraying the bumper with compressed air.
Seal the bumper with a flexible bumper sealer. The sealer will give the paint extra adhesion and will help keep any repairs from feathering out into the paint.
Spray the bumper with an aerosol texture coating if the bumper was previously textured. Let dry completely, then scrub it with a scuff pad to take the tops off of the texture. Spray the texture spray on once more, let it dry completely, and then briefly sand with 320-grit sandpaper to remove any strings of texture or lumps that may have accidentally occurred.
Prime the bumper with a flexible bumper primer surfacer. Spray evenly across the entire front side of the bumper. Let dry before moving on to the next step.
Paint the bumper with a bumper colour coat. Let it dry before wet-sanding with 320-grit wet/dry sandpaper. Rinse thoroughly, then let it dry. Repeat this process four times.
Apply another coat of paint, let it dry, then wet-sand with 400-grit wet/dry sandpaper. Rinse, dry, and spray once more for a finish coat of paint. Let dry for 12 to 24 hours