How to Clean Cloudy and Yellowing Headlights
Someone once told me that best way to make an aging car look like new is to replace the headlights and windshield. More and more I agree with that statement as I've found even if the car is dented, scratched and unclean, if the headlights and windshield are crystal clear it will look great.
When I picked up my Vehicross a few weeks ago one of the most noticeable visual blemishes was the horribly cloudy and yellowing headlights, this VX had been sitting under a tree in the sun for a few years so it was pretty bad.
I've found the best way to fix anything is to first determine why it broke in the first place. So before we clean our headlights, it's a good idea to understand WHY and HOW the headlights became cloudy and yellow in the first place.
Why it happens
The VX like many cars use a plastic housing for the headlights. Like most plastic it takes a beating from the sun when exposed for long periods of time. the kind of plastic used in headlights is quite different than that used in cladding or elsewhere. The chemicals used to make the plastic crystal clear also make the plastic quite brittle (at least as far as plastics go), while technology has improve over the years (consider how easily those old Clear CD cases would crack) it is still susceptible to damage.
Over time a combination of dirt, bug, and other small objects pelting your headlights, and combined with the heat from the sun causes thousands of microscopic cracks and pitting in the surface of the headlight to occur, these can cause the headlight to look slightly faded or cloudy. Over time these cracks will fill with dirt and oil getting kicked up from other cars or delivered by rain water, this causes the headlight to appear yellow. You're actually seeing grime accumulated in the hairline surface cracks.
How do you get rid of it
Knowing how this is caused we can better understand which methods will and wont work. Most headlight "restoration" kits are a form of polish that will slightly smooth the surface of the headlight and clean out the cracks somewhat, but they don't really solve the problem, they're just cleaning the cracks and making them less noticeable. some will include a "sealer" that attempts to keep the cracks from expanding or getting dirty again, but again not a final solution. More aggressive restoration kits will actually use a chemical to melt the outer layer of the plastic these can work quite well but if you're not careful with your use you can actually make the surface of the headlight uneven (it will look like "streaks") sometimes this will be so bad that it can't be repaired
The method I like to use personally is to simply sand and polish, this will in effect sand down the surface of the headlight until you've removed all of the scratches, and then polish the surface to smooth it out and bring it back to it's original clarity. the result is a set of headlights as clear as they were from the factory and will hold their clarity as well as a new set of headlights.
My Method:
pick a clear day where you can dedicate 30 minutes to an hour per headlight.
I start by popping the hood and use some painters tape to mask off the body around the headlight. you can opt to remove the headlights altogether, which ever you feel would make it easier for you.
From there I take some 1000 grit sand paper and a bucket with a small amount of water on the bottom, dunk the sand paper in the water and using nothing but the paper and your hands lightly sand the entire surface of the headlight. Work your hand in a circular motion applying light even pressure as you go. This will make the headlight look "milky" as you're removing a slight layer of plastic from the headlight. keep dunking the sand paper to keep it soaked and work around the headlight.
After you've thoroughly sanded the headlight, take a shop towel and dunk it in the water and clear off the residue from the headlight. Don't be alarmed the headlight will be extremely cloudy at this point. you should however take a look closely and determine if the surface of the headlight looks even or if there are areas that still show some of the originally cloudyness from before you started. If there are areas that could use more sanding, dunk the sandpaper some more and go around the headlight completely, even if only one area needs more sanding you'll want to do the whole headlight evenly.
Once the surface of the headlight looks uniform use water and shop towels to make sure it's clean and dry. Next you'll want to apply polish to return the headlight to it's original smoothness.
Some people prefer to do a 2nd round of wet sanding with 2000 grit paper doing so will reduce the amount of polishing required but it's not vital to the process.
For polish you'll want to use something designed specifically for smooth plastics. I actually use the Blue Magic Headlight restoration compound. When used alone this stuff will improve the headlights a little but it doesn't remove the cracks so it starts to get cloudy and dirty again after a few months but when combined with wet sanding it works exceptionally well.
You'll want to put the polish on a shop towel and really work it in, use a lot of polish and even more elbow grease. you'll wan to apply this like wax, so put on a layer, and then use a clean shop towel to take it off. If you skipped the 2000 grit step it make take 4 or 5 rounds of polish to clear up the headlight, if you did a 200 grit wet sand then it should only take 2 or 3 rounds of polish.
Once you've finished polishing take a look at the headlight and determine if there are any areas that could use additional polishing or any areas that could use additional sanding. If your headlights are really bad you may opt to repeat this entire process a 2nd or even 3rd time.
Here is how my passenger's side headlight looked after 1 round. you can see how improved it is compared to the other untreated headlight. Up close it still was a little cloudy in spots and I opted to repeat the process a 2nd time.
Other Considerations
I've used this method on countless cars and it always has exceptional and long lasting results. while not an option on a VX if you do have the option to purchase replacement GLASS headlights I recommend doing so as they will not pitt and yellow like plastic does.
On other cars with more flat headlights I made use of a sanding block, though for the VX, because of the curvature you're best simply using your hands.
I did my headlights by hand, but if you have a buffer you may be able to expedite the polishing process, though I would recommend removing the headlights for that.
The Results
Ahh... looks like those headlights are brand new
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