A buddy of mine gave me his headlights after helping him replace them.
He had gotten in a little fender bender and the insurance bought him a
new set. So instead of polishing out the old ones, he just got new
ones. Sweet deal! Anyway, this was three or four years ago and I had
put the headlights up in the loft in my shed and forgotten about them. I
was poking around up there on Saturday and found them and decided to
see what kind of difference a little polishing up would do. They were
pretty crusty and yellow, so this just seemed like a really good test.
These are from a 2001 Integra. I have no idea how we let them get this bad, but sometimes you just don't realize how nasty lenses get as they slowly oxidize and yellow.
I taped off half of the lenses so you could see a good before/after type effect. Sometimes you really need to see them side by side to tell the difference and I wasn't sure how much difference I was going to be able to make.
I hit them with my big guns. I had my rotary with a blue polishing pad on it already plugged in and on the work bench from another project I had worked on, so I decided to use that. I also had some XMT4 sitting there, so I decided to use my most aggressive machine with my most aggressive polish and see what kind of repair I could do. The blue pad isn't the most aggressive, but with that polish it doesn't matter. It could take the white off your teeth it is so gritty. lol
Here it is right after polishing. I was shocked that it only took like 45 seconds to get results. With that combo the yellow crust just melted off.
See what I mean about it being hard to tell the difference unless you see it side by side? You can see the brown polish on the tape and that is how I know this is the 'after' picture. Check out what it looks like when I pull the tape off though!
Here they are out in the sun.
The point is that I turned something my buddy was just going to toss into something worth money. Nobody would have bought those in the condition they were in. Once they were cleaned up I had to beat buyers off with a stick. The process of cleaning them up was ridiculously simple too. It just took a little car polish and a machine. They actually make smaller attachments and pads that you can use with a drill specifically for headlight repair like this. Don't go paying someone $50 or $75 bucks to polish your headlights when you can do it yourself for much less.
Plastic lenses are often clear coated to protect the plastic from UV damage, but over time and after a few years of neglect the clear coat will start to peel off and look terrible. It may be that you need to sand the rest of the clear off before you can polish and it also may be that the plastic has been UV damaged so badly that replacement is the only option. You won't know until you try though. Crusty yellow headlights really detract from the car's overall appearance. Polish them up and put a coat of wax or sealant on them when you do the rest of your car to keep them somewhat protected. It is better than spending big bugs on OEM replacements. I know you can buy aftermarket lights for about $150 shipped, but do you really want to have to do that if you can just polish yours out? And what about the resale value of your lights? I sold my OEM lights after I put projector housings in and it covered the cost of my replacements. Your yellowed lenses won't do that for you, so polishing them up is a good investment.