1. 800 grit 3M wet/dry sandpaper (one package should be enough)
2. 1200 grit 3M wet/dry sandpaper (one package should be enough)
3. 1400 grit 3M wet/dry sandpaper (one package should be enough)
4. Metal polish or fine-cut cleaner/rubbing compound and buffing wheel. AutoZone should sell an aluminum oxide-based compound in a kit that comes with a buffing wheel that attaches to your drill for about $13.00 or so.
5. Small water source (a squirt bottle or a trickling water hose will work fine
1. Be sure to tape off all painted areas in close proximity to your headlights (i.e. front clip, hood, frontward part of fenders. You don't want the sandpaper to slip and scratch your paint!
2. Taking a sheet of the 800 grit paper in one hand and the water source in the other, gently but thoroughly wet sand each headlight lens until it is visibly hazy. This removes the outer surface of the headlight lens (the part that is yellow and ugly) and lets new plastic show at the surface. BE CAREFUL not to sand with too much pressure, for the 800 grit paper is efficient and you don't want to scratch the lens so deeply that you cannot buff it out.
3. Take the 1200 grit paper and wet sand the area that you just roughed out with the 800 grit. If you did make really deep scratches with the 800 grit, use 1000 grit before the 1200 grit. Carefully wet sand and pause, checking to see that the lens face is beginning to get ever so slightly smoother. Time spent on this step will vary depending on how deeply you went with step 2. When satisfied with sanding, dry off and inspect the lenses. They should still have an opaque haze caused by the sandpaper scratches, but the scratches should be much much finer.
4. Repeat step 3 with 1400-1500 grit paper. You should notice that the lenses are starting to loose some of their opaqueness caused by previous sanding. Sand as necessary until only extremely fine scratches are left on the surface. Dry the lenses and prepare your drill or buffer for buffing.
5. The rubbing compund/polish should be good enough to buff out scratches left by abrasives similar to 1400 grit sandpaper. I found that the kit from Auto Zone works really well because the buffing wheel is small (about 4 to 6 inches in diameter) and padded, making it very suitable for the job at hand. Place a dollop of compound about the size of a quarter on the buffing wheel and slowly buff each headlight using medium drill or buffing speed. Check your progress often by rinsing off the compound and drying the lenses. It is important to dry the lenses, because the water will fill and small scratches that may remain and give your lenses the appearance of glossiness. Repeat buffing and rinsing until all of the ultra fine scratches left by the sandpaper. When you finish, you will find that your lenses will look like new again with no opaqueness and maybe only a hint of yellow if you look very very close.
This article is a repost from http://www.tccoa.com/articles/exterior/index.html