Many people have vehicles with plastic bumpers or plastic end caps on metal bumpers which are often damaged through off road work, or just general wear and tear of a vehicles life. Many suffer external or superficial damage which is easily repaired by repainting, others become cracked or shattered; it is these which can be easily and cheaply repaired by the average individual and at a lesser price than replacing with second hand items.
If all the pieces are there, or only some smaller items are missing it can be repaired by using polyester resin, or fibreglass as it is better known, fibreglass kits are available with resin, hardener, and glass matting already included. In addition you will need solvents to clean brushes, rubber or latex disposable gloves, and a little time to make an effective repair at a reasonable price.
Remove the broken bumper, if access is easily gained without removal this is not necessary, and ensure you have any broken pieces, rub these and the surrounding areas on the rear face with 80 grit sandpaper to provide a good bond. Mix a small amount of the resin and hardener and prime the abraded surfaces with a thin coat of resin and allow to harden, if it is cold it may need a little heat to begin the reaction, a 500w halogen in close proximity is ideal.
Cut some of the matting to a size larger than the affected area, mix a little more resin and paint the primed surface again, place the matting in position and using the surplus resin, paint the matting with a stippling motion. The matting will visibly change colour as it absorbs the resin, if it does not change colour evenly then add more resin and apply until it does change colour and fully absorb the resin. Repeat this process twice more until the area has three layers of matting, with the final coating in place, cover the entire wetted area with a piece of cling film and allow to thoroughly dry overnight.
Move to the front face and remove any resin which has come through the cracks, open the cracks to a “V” shape with sandpaper or a small tool like a Dremel or compressed air die grinder. Fill these “V’s” with stopper; stopper is very fine filler and is much better than ordinary filler as it can be sanded so thin, it actually ends up thinner than individual coats of paint, and is available from body shops or paint factors in small tubes. Allow the stopper to thoroughly dry as it shrinks slightly, sand with 600 grit wet and dry, dry once flatted and apply a second coat of stopper to fill any highlighted imperfections, allow to dry, and wet sand again with 600 grit wet and dry, wet.
Prime with high build primer, wet flat and refinish with paint and lacquer.