Vehicle headlights develop a film over time, often referred to as cloudiness. This film dulls the light and disperses it in a wider pattern, giving the illusion that the headlights are weaker, as well as making it difficult to drive at night. Regularly cleaning cloudy headlights is an important safety measure that every driver should perform. Different chemical solutions are for sale at auto shops, but home remedies are often just as effective and generally cost-free.
Salt is an abrasive substance, and will lightly scratch any surface that it is rubbed into. Mixing salt with a small amount of water and rubbing the cloudy film on the headlights vigorously will cause the cloudiness to be etched off of the plastic.
Vinegar is an acid substance, and is often used to spot-clean fabrics, metals and plastics. To remove cloudiness from headlights using vinegar, submerge the headlight in a bucket filled with white vinegar and let it rest for at least 60 minutes. After soaking, the cloudiness should be soft and easy to wipe away with a mildly-abrasive cloth.
Sandpaper is more abrasive than salt, and is ideal for very cloudy headlights that are difficult to clean. Using any sandpaper available, gently rub the cloudiness in circular motions, pressing lightly until the cloudiness is gone. Polish with vegetable oil, car wax or plastic polish to remove the small scratches that sanding will cause.
Sometimes cloudy headlights are due to small scratches and scuff marks on the headlights instead of corrosive buildup. The scratches on the headlights must be polished to make the plastic clear and shiny again. Any wax or polish intended for plastics can be used to polish the headlights. Using a soft cloth, such as micro-fabric wipes, rub polish into the headlights in a single direction until the polish is eliminated. Repeat until the scratches have disappeared.
Stagnant water that gets under the headlights often leaves water burn marks in the plastic. To remove discolored watermarks and cloudiness due to oxidation of the plastic, use any metal or silver cleaner and rub the headlights with a mildly abrasive cloth. Do not allow the metal polish to remain on the plastic for too long, however, as it may damage the plastic.
A buffer intended for fingernails can be used to polish headlights, which works by eliminating small scratches and giving the headlights a like-new sheen. Using a small amount of metal or plastic polish, rub the buffer in small, circular motions across the headlights until they are clear.