to fix yellowed plastic headlights and scratched/weathered lenses.
i use and highly suggest 3m and meguires products
-materials
high speed buffer (1500-1800 rpm)
rubbing compound (liquid type, hard cutting)
high quality liquid wax
1200 and 2000 grit sandpaper (wet sanding type)
either water or better yet, mequires final inspection spray
masking tape
step one:
mask painted areas, or remove lens, whichever is easier
step two:
use water or meguires spray to lubricate surface, for more weathered lenses, use 1200, then follow up with 2000 grit sandpaper. use light to medium pressure, ensuring to get all surfaces sanded.
step three:
remove water/debris with lint free towel or chamois
step four:
set buffer to 1500-1800 rpm, use clean foam pad or buffing pad, apply a quarter size of both compond and wax in the center, then stream a line out from the center in a circular motion.
step five:
apply buffing pad to surface, try to get most of the polish and wax onto the lens before turning the buffer on, then proceed to buff the surface, using up and down, back and forth motions. you should see the compond/wax mixture begin to thin out and the lens should begin to shine greatly, be sure to avoid rubber and painted trim surfaces.
step six:
use a soft towel, or a microfiber cloth to remove residue, remove masking tape, the lens should be significantly cleaner and more transparent, if yellowing remains, repeat process until desired results are achieved.
enjoy!