Had Turtle wax headlight restorer, and meguires Plastx. meguires ruled, redid the turtle wax one with meguiar’s , hand buffing with a paper towel, now I have cataracts, but not my car. Tried buffing with a dremel a couple of years ago, no noticeable advantage.
In the last month I’ve done 3 sets of lenses.
I start with 600 grit wet sand paper until all the imperfections are gone. Then I use buffing compound with a 3inch buffer in a drill.
Then I finish them with a coat of wax.
It takes about an hour to do two complete lenses.
Yosemite
Sounds like a good way to go, would that be a sheepskin buffer, or a hard cotton one? @Yosemite
I’ve had excellent success with a wetted sponge on a variable speed drill and regular polishing compound, waxing after polishing. I’ve polished many lenses using this process.
I empathize on the cataracts. I’ve had to have cataract surgery on both eyes. I like to say I have “store-bought lenses” now.
@Barkydog, it is a sheep skin one, but I had to make it myself. I couldn’t find a small bonnet.
I just used contact cement to glue the sheep skin to a “Twist loc” pad
Yosemite
Just for the sake of discussion, I would like to know if the forum members who have had problems with fogged headlight lenses are in the habit of parking their vehicles outside.
I ask because none of my garage-kept vehicles has ever had this problem, even after as long as 11 years.
My vehicles only have problems with headlight lenses fogging when they are parked directly in the sunlight. My wife always parks in the garage or carport and she never has a had a problem with headlight lens fogging. So…completely unscientific here but I believe sunlight is the culprit here when it comes to lens fogging. .
^
Thank you, missileman, as that is my theory also.
Yeah ours are inside 90% of the time too and never fogged over but like I said, I clean them up with Plastix twice a year.
Outside parking, The thing I don’t get is it is only the headlight lenses, perhaps parking outdoor residue gets on the lenses and that and the heat causes the issue, if the indoor no problem continues, maybe cleaning the lights every am might prove an interesting experiment. Also I wonder if it is related to daytime running lights, I have those.
I always thought that the cause of the fogging was really pitting from minute dirt particles striking the plastic lenses.
Yosemite
I might think so also, except it is a large lense that also includes the turn signal, but the fog is only in front of the headlights. The part in front of the turn signals is tapered, but anything is possible?
@Yosemite
Pitting can be contributing factor. The main issue is loss of the protective coating which exposes the underlying plastic to oxidation. The coating can be loss by pitting and by its own reaction with sunlight.
It’s Deterioration And Crazing From Sun And The Elements. Pilots Have Known This For A Long Time. Long Before Cars Had Plastic Headlights, Airplanes Have Had Plastic Windshields. Covering The Windshield Or Keeping It Out Of The Elements Kept It From Deteriorating And Crazing Just Like With Headlights.
CSA
When polishing lenses on the car, one slip can damage adjacent paint. It’s a wise precaution to mask off the area around the headlights with something more substantial than just masking tape - like plastic from milk jugs, for example.
Headlight requirements are actually pretty extensive.
I’m no chemist. But I do recall reading that the process by which lighting modules degrade involves UV rays and temperature. I searched unsuccessfully on the internet to find out what polymer is used on modern headlight modules and its properties. If I were a chemist I’d know what to look for and could, I’m sure, find the answers. But, alas, I’m not. 
The good news is that they’re so easy to polish.
Yeah, I think UV has a lot to do with it. Neighbor kept his car outside, it fogged up, mine didn’t, same age.
As far as I can tell from the quick research I did the plastic in the covers is usually polycarbonate (the same stuff they use in lighter eyeglasses and quite a few other things). It is very resistant to impact cracking, but not so much to UV damage and pitting. The source I used mentioned both a UV filter coating and a hardening coating to resist pitting. At some point, I suppose those wear off. In any event, any UV coating is like sunscreen–it just lengthens the time it takes to damage what’s underneath.
It’s also softened by acetone, but probably not too badly with quick exposure.
And yes, I am a chemist. Hope this is helpful; I learn a lot here.
VCDriver You are rite on with the parking outside. I don’t have a place to park inside & my pickup & car my wife used to have both had the clearcoat paint that the sun did a number on
The fogging of the headlights is primarily from UV. Notice that headlights with curved profiles typically have the most oxidation at the top. My solution in an earlier post is the most effective because it helps limit future UV exposure. Sanding followed by application of a clear coat finish, designed to reduce UV exposure to your car’s paint, is the most effective solution, short of new lenses. All other solutions will eventually require another treatment within one to two years.