Plastic headlights can fade, yellow, oxidise or deteriorate over time. Exposure to high-speed impact from road debris, bugs, rain and ice all can create pitting and dulling of the exterior finish. Ultra-violet light from sunlight can degrade and yellow the surface of the plastic causing further cloudiness, dulling or discolouration. Restoration of the plastic headlight requires removal of the thin outer surface of headlight material which is deteriorated. Once the damaged layer is removed, clarity can be restored.
Wash and thoroughly clean the headlight.
Select a headlight restoration kit based on ease of application and tools available. Restoration kits are available from Diamondite, 3M, Meguiar's, Mother's and other manufacturers. Some restoration kits require an electric drill to allow high-speed buffing.
Apply the manufacturer's product and buff the headlights according to instructions. The buffing will remove the outer layer of the plastic headlight. Some kits may also restore the gloss, polish and clarity in the same step.
Apply a headlight protection product. Many restoration kits include a protection product which is applied during the buffing process, or afterward, to ensure the headlight is protected from oxidation and ultraviolet damage. If no product is included, apply a quality car wax which includes UV blocking. Wipe away any residue remaining from the restoration product or car wax with the soft cloth.
Clean the headlight with a glass cleaner to remove any oils or debris from the surface of the headlight. When sanding the headlight, debris or oil can clog the sandpaper. Clogs keep the abrasive material on the sandpaper from removing the degraded layer of headlight material.
Sand the entire surface of the plastic headlight with the 600-grit sandpaper in circular motions to avoid cutting grooves in the surface of the headlight. Frequently rinse the sandpaper and the surface of the headlight with water to remove debris released from the sanding effort. Due to the fine grit size of the sandpaper, small particles, sand dust and abrasives released while sanding can easily clog the sandpaper which will reduce the effectiveness of the sanding effort. Evenly sand the damaged layer of the surface of the headlight until clarity is restored. The sanding will leave a dull finish on the surface of the headlight, but will remove fading, yellowing, oxidation, pitting and fogging.
Polish the surface of the headlight with 1200-grit sandpaper to remove sanding marks left from the 600-grit sanding. Frequently rinse both the sandpaper and the headlight surface with water to avoid clogging the sandpaper. Using small circular motions, evenly sand the surface until all the sanding marks are removed from the headlight. The headlight surface should be clear of scratches and marks. If a sufficiently deep layer of material was removed, full clarity will be restored.
Wash and dry the headlight to remove any excess sanding debris. Wax the headlight with a quality car wax to ensure it is protected from oxidation and ultraviolet damage. Wipe and buff the headlight with a soft cloth to remove any wax remaining and to create a clear shine on the surface of the headlight.
The abrasive sandpaper can scratch, dull or mar the surface of the vechicle's paint or trim. Use sandpaper sections approximately the size of your palm to maintain control of the sandpaper while restoring the headlight.