I had at one point, decided to do this as after washing the prelude, the headlights were the only sore spot. I proceeded to research like crazy and obviously failed in hitting the right links as I decided to do (following "well" researched net articles and posts):
- Sand the headlights down
- Use a microfiber applicator (small sponge covered with MF) and my stock of random Meguiars scratch remover polish to plenty of elbow grease.
- Stand back and marvel (never got here)
Following my new detailing bible from detailed image, especially their headlight care section, I decided to use my newly acquired Menzerna polishes (Power Finish and Super Finish) and the new 4 inch Lake Country pads (Yellow regular and the Cyan and Tangerine Hydrotech pads) for the job. I only had the 2000 grit wet.dry paper lying around and decided to see how far I could get with the polishes alone. I realized that unlike clearcoat and paint, the plastic of the headlights is very hard and would require some work to polish. Still, I was hopeful as the inspirational links promised very good results with my plan of action.
On the prelude I taped the trim and then used the Cyan pad with the Power Finish polish followed by the Tangerine pad with the Super Finish polish. I cleaned out/buffed with a microfiber towel after each polish stage. The Porter Cable polisher was set at speed level 4 or 5. The results were very good. Please forgive the different angles, but each headlight looked like the right one does: pretty clear.
Once this was done, I started on the Accord. After fighting with it for a while with the Cyan and Power Finish, the headlights still looked pretty bad. It looks like the wet sanding done several months earlier on the Prelude must have helped. It was already getting cold and I was getting tired, so I did a few passes with the 2000 grit paper (the links from DI indicate the need for progressive 1000, 1500, 2000 and 3000 grits, each done in X first and then Y to produce a hatched sanding pattern) and decided it was done.
Accord before the cleanup
After Wet Sanding
Once wet sanded, I cleaned them up with water and then proceeded again with the Cyan/Tangerine combo (I also hit it with a yellow pad, the most cutting power I had before I decided to sand as the Yellow+Power Finish were not enough), I finally got this..
Note that the hazy/dull sections are actually reflections of the apartment complex. It came out looking pretty good. Will not compare with new headlights, but for a 10 year old plastic piece that has lost it's UV protection and has been battered by billions of tiny projectiles: the old mama looks good again!
Very satisfying day all in all. Folks with yellowing headlights who also have access to polishing compounds should definitely try this: makes a big difference. You can use elbow grease if you don't have a polishing machine. Chemical guy's also has a "Headlight Restoration & Protection System-GlassyLite" listed in their glass care section. I also see other headlight restoration kits being sold at Pep Boys and Auto Zone but have no experience with either.