My civic is a 56 plate, and has(had) really badly deteriorating headlights.
The surface of the headlight had started to get quite brown and faded. I decided to give the headlights a bit of a spruce up with one of those kits you can buy where you attach some sandpaper to a spinning disc on a drill.
Well, the results weren't that good... mainly due to the fact that I hadn't charged my drill up overnight and it wasn't spinning very fast, my fault
I only managed to get one headlight done that evening, before the drill just died completely.
Now the sanding had indeed got rid of the scummy surface and brown colour from the headlight, but now instead of being clear the whole thing was cloudy (albeit a clean cloudy).
If you're not aware, the kit comes with 3-4 sanding discs, you start with the small number "grit" to get rid of the rough surface and grime then after each pass you move to the larger "grit" paper to get a smoother and smoother finish. Finally there's another attachment with a foam pad which you're supposed to use the provided "polishing compound" on the lights.
You get 2 sets of the above, obviously 1 set for each headlight... but the light wasn't clear enough and I had to use the 2nd polishing compound to get the one light clear enough to drive with.
Over the following weeks/months, I'd simply not had much time (and the weather had been crap) to buy another kit to do the other headlight and yesterday I put the civic through it's MOT.
It passed, but one of the advisories was "Headlamp deteriorated but light output not reduced - both". It had been a few months since I last took any notice of the headlights to be honest, so I looked and the headlight I'd not tried to restore was really bad.
Then I remembered I had an old bottle of T-Cut for silver paintwork. I thought it might work as a polishing compound, so I applied some to the crappy headlight just for giggles... nothing to lose really, as I might be in for a set of new headlight clusters anyway.
It only bloody worked didn't it!!
I only had 10 minutes before I had to go watch the football with my mate, but in that 10 minutes the crappy headlight is now the better of the 2. It will need another going over, but all the brown/green/yellow fading has gone and the lens is perfectly clear again.
Just thought I'd share