first take 1 set of badly scratched and dull lights
then rub down with 1500 wet and dry (halfords) using lots of water (this took me 10 minutes a side and I contiued until they felt smooth) This can be quite messy, and you'll need to wash them well after this and leave to dry!! At this point they will look cloudy...
like this
Then I used some meguires stage 2 paint cleaner (Its similar to most basic cleaners and t-cut will do the same job, if not better?) I applied this with my machine polisher with a medium sponge (A drill with a similar sponge would do the same) and ran over them for a few minutes using 2 speeds.
and this gave me
and to make them shine i used meguires stage 3 carbuna wax (something i had lying round the house!)
and i now have
Total cost 40p for the wet and dry...everything else if basic polishes that most people will have lying around?
