A dent or scratch can be an unsightly nuisance on your plastic bumper. If you have the correct equipment and materials, you can repair even serious damage like a crack or hole on your bumper. It only takes a few steps, though you will need to remove the bumper first.
Remove the bumper using the method recommended by your car manufacturer in the user manual.
Clean the bumper with a damp, clean cloth to ensure that there is no dirt or debris clogging up the bumper when you do your repair.
Sand off the rugged edges of the damage. Use a sander equipped with a 36-grit sanding wheel, and sand until smooth and shaped.
Sand the front and back of the plastic bumper with 80 grit sand paper to add more smoothness to the repair area.
Clean the repair again, using the same method as in Step 1. This will get rid of the dust and debris which might have collected during the sanding process.
Apply adhesion promoter on both sides of the bumper. Wait for around 10 minutes for the product to cure and seal.
Apply structural repair adhesive to a backing re-enforcement material such as plastic, enough to cover at least 1 inch around the back side of the repair. Apply the backing material to the back side of the bumper. Let any excess adhesive ooze through the holes and grooves of the bumper.
Lather on some more adhesive while it is still wet and place contouring plastic on the top.
Wait an hour, then sand the area again using your sanding wheel on a low RPM speed.
Finish off the repair using plastic finishing putty or filler to fill any dents or imperfections.