Plastic Polishing

Clear and semi-opaque car parts really show their signs of wear. Scratches, smudges, stains and yellowing can make light lenses, gauge covers and even convertible-top windows look prematurely old.

In many cases, hairline scratches can be buffed out using a plastic-polishing product.
In many cases, hairline scratches can be buffed out using a plastic-polishing product. Most of the major car-care product companies offer a chemical that's formulated to rejuvenate everything from the clear vinyl found in convertible tops to the hard polycarbonates that comprise modern head- and taillamp assemblies and wheel center caps.

Hard Duty
Like their automotive-paint equivalents, plastic polishes permit some surface flaws to be whisked away by hand. Some products utilize the spray-and-wipe method while others require a process that's similar to paint revival. For the latter polishes, first apply the product liberally to a soft cotton towel or polishing pad. Then, rub onto the afflicted area using a circular motion. Once the polish dries to a haze, buff it out with a clean cotton towel. Many plastic polishes leave behind a protective polymer that helps protect the plastic against yellowing and premature aging caused by ultraviolet (UV) rays, air pollution and acid rain.


Deep scratches in Lexan and other hard polycarbonates often go beyond plastic polish's capabilities. Professional detailers will sometimes try to treat serious plastic scratches as if they were in glass. Cross-hatch sanding followed by machine polishing is one way that pros attempt to revive badly scratched plastic. However, the average do-it-yourselfer is probably better off not risking further damage by using these heavy-handed techniques. Instead, polish the scratched area multiple times to make it look as good as it can under the circumstances. If the results aren't acceptable, consider replacing the part.

Software
Many convertible tops use polyvinyl windows. Exposure to UV rays can cause the plasticizers that make this plastic pliable to be released, which causes haze. Many plastic polishes are formulated to remove this haze and yellowing as well as mild scratches. Follow the instructions on the bottle to achieve the best possible results. Be sure to protect the top's fabric with a plastic drop-cloth when using these products. To prevent further scratches when washing the car, use a special synthetic chamois or a cotton polishing cloth, which suspend dirt better than a normal cotton terrycloth.