Headlight fine crazing on lens ?

[isrod]

My headlamps have gone foggy as they do so I cleaned with a rubbing compound and polished up and they look far better but in the lens the plastic/glass cover have very fine cracks/marks in them which polishing doesn't seem to move it almost looks as if it is on the inside of the lens has anyone come across this and found a solution? 

[Mr Vlad]

Hi Rod. Funnily even though I've had my car a year now I only noticed yesterday the driver side headlight looked much duller than the passenger side. The root causes was residue from a wrap that was on the lights when I bought the car. Don't understand why residue left on driver side and not passenger side which actually look like new. 

I used a solvent to try to remove the residue but that didn't work so I used a 1200 grit wet n dry paper with the solvent. No change. 800 grit paper with water and lots of elbow grease. Residue 90% gone so then 1200 grit then 2000 grit and then Maguires ultimate compound then a polish. Overall over an hour But there are very fine cracks. They're still there and I'm of the thinking it's down to age and them perished but sunlight over the years. Not an MOT failure as they've been there since I got the car and got it MOT'd. 

If those cracks are really unsightly then the only thing is to replace with a used item.

[Linas.P]

Not much you can do about those cracks - I had my headlights polished few times as well, but there were some fine cracking inside the plastic. I assume this is what happens when car is left in sunlight without proper UV protection  (e.g. when you have dull lights your headlight coating is likely failed by that point) - over time the plastic itself starts deteriorating. 

As above, ultimately replacement is only option, but I would avoid used lights - they are quite likely to have exactly the same issues.   

[isrod]

Had my mot Monday and it failed on poor rear right brake the headlamps had no issue so cracking is ok considering it's year , I have had the car 4yrs now and in that period I have refurbed the caliper on the right rear twice this time I treated her to a new one 60 quid off eBay and an hour to fit passed test for 100 quid happy chappy