Most headlight lenses are made of polycarbonate plastic. This strong plastic is perfect for taking on harsh road conditions without breaking, but it doesn’t play well with the sun. To protect it initially, manufacturers coat the lenses with a UV protective film. Over time this film is destroyed by UV rays, allowing the plastic to oxidize.
If your headlights have started to haze over or become yellowish, then it’s clear the oxidation process has begun. Don’t worry though, because getting those headlights looking new again can be done.
Start by making sure you have the supplies you’ll need. Basically, you need a few different grits of wet/dry sandpaper (1000, 2000, and 3000 grit are typically safe bets), polishing compound, paste wax, and a UV sealant. Also buy a roll of blue painter’s tape and microfibre towels.
The first step will be a thorough washing of the headlight lenses with car soap and water. Wash the surrounding areas a bit, too, so that the tape will stick during the next step.
You’ll be sanding in a minute, and it’s important that you sand only the lenses and not the surrounding paint or trim. So use the painter’s tape to completely block off the headlight and protect the rest of the car.
The sanding process is the same whether you bought the kit or just the materials.
You’ll want to start with the most abrasive sandpaper option you have. If you followed my advice and got 1000, 2000, and 3000, reach for the 1000 grit (lower numbers mean more abrasive). Wet the sandpaper and the headlight and then sand the lens in straight, horizontal strokes. Make sure you sand in the same direction the whole time with this first one. Also make sure you keep the surface wet as you work otherwise you risk badly scratching the lens due to grit particle build-up.
Repeat the process with the less abrasive sandpapers—in this case, the 2000 and then the 3000 grit. The only difference with these two will be the direction of your sanding motion. Since you used horizontal strokes with the first sandpaper grit, then you’ll want to sand diagonally across the headlight for this next one. The final sanding should be in the opposite diagonal motion from the one you just did. Take your time and ensure the paper and lens stay wet with water. A hose or spray bottle work wonders here.
Now it’s time to reveal the cleared headlights. Wipe off and dry and then squeeze some of your polishing compound onto a clean microfiber towel. Rub in the polish for a few minutes using circular motions. You can get through this process quicker if you have and are comfortable using an orbital buffer. Once you’ve made the lenses clear again, you can take the wax to it.
Please note that the headlights can also be treated with ceramic coating. This will ensure that your headlights will remain clear and will protect them from more damage.