Headlights begin to fade over time, and there's no way around it. As your headlights fade, the amount of light that makes it out of the headlight becomes less, and before you know it, driving at night becomes difficult, but more importantly, dangerous. This is due to oxidation on the lens. Once oxidation begins to take place, it quickly degrades the headlight lens, because polycarbonate is a porous material. Wet sanding (what we will be doing) helps to remove this oxidation and restore your headlights to a safer condition.
I have been restoring headlights now (mine and a few friends and family) for quite some time, and I feel that the knowledge should be passed to others. So without further adieu, let's get started.
What you will need:
-Sand Paper with values: 800, 1000, and 2000 grit.
-A Small Towel, Rag, or Microfiber Cloth
-3M Rubbing Compund
-Automotive Masking tape
-A Drill (corded or cordless)
-Compound Pad (Wool pad works as well), with drill adapter
-A Spray Bottle with Water
-A Small Measuring Cup (one you don't use for food)
-Minwax's Helmsman Spar Urethane : Clear Gloss.You need this specific kind.
-Odorless Mineral Spirits
-2 to 3 Hours put aside (depending on your attention to detail)
Now, we need to tape up the area around the headlights. This is the first and most important step of the whole process. You want to make sure to tape up any and all paint surrounding the headlights. You will be spending quite some time on your headlights. After all your hard work work is done, you don't want to have to fix the paint as well!
Next, after all the taping has finished, we can begin the fun.
-Cut your sand paper sheets into fourths (I found mine at Walmart for about $3 and change per pack. Each pack contains 5 sheets.)
-Get out your 1/4 sheet of 800 grit sandpaper, and spray it with the water bottle. Place the sand paper on the headlight (it will stick by itself) and continue to spray the whole headlight until the whole headlight is wet.
-Slowly start sanding the headlight making sure to spray water while you sand. Water isn't needed, but helps to make the paper last longer and make it easier. Make sure to sand all the edges and all the corners. Do this for both headlights, making sure not to reuse the sandpaper from the opposite headlight. 1-1/4 piece of sandpaper per headlight.
Helpful Tip: Sand in one direction. This makes it easier for you to check and see that your lines are consistent and that you have sanded the headlight evenly. It also helps to see anything you might have missed.
-Continue sanding until you can see a uniform surface of 800 grit scratches (where sanding in one direction helps). Wiping the surface with a towel or shop towel helps to check. When you have removed all the oxidation, and there is a uniform finish, continue on to the next step.
When you get a uniform finish, you will notice the headlight is beginning to clear up (but only slightly). wipe off the water and move on to the next step.
After you get a uniform finish, you will notice the headlight has cleared up again. This time more noticeable than the last. Good news, this is the last of the sanding. Now your hands can get a break as we continue on to the next step.
Take your rubbing compound and shake it well. Open the cap and apply a decent glob on the headlight. Take your compound pad and rub the compound on the headlight without turning the drill on. This helps to keep the compound from splattering all over the place when you begin.
Making sure to start slowly, turn on the drill and begin polishing the headlight. When the compound has spread, turn the drill onto full speed, making sure to cover all areas of the headlight. This process helps to get rid of the 2000 grit scratches and gets the headlight shiny and new.
Make sure to polish the whole headlight, using more compound if needed. The headlights should now shine and, depending on how well you did on the 2000 grit step, should start to look brand new. You are almost done. We can now move on to the next step
Take the urethane and pop the top. Pour half an ounce (or an ounce depending on how accurate your measuring cup goes) of urethane into your measuring cup.
Now take your mineral spirits and add the exact same amount as you did for the urethane into the measuring cup. The mixture should be 1:1, so 0.5 ounces urethane to 0.5 ounce mineral spirits to make one ounce of clear coat (or 2 ounces if you used 1 and 1).
Stir the urethane and mineral spirits mixture. After doing this step, use a shop towel and the rubbing alcohol, and wipe the headlights clean. This will get rid of any compound left on the headlights.
If you would like, you can wash the car now, as after we apply the urethane, you won't want to touch the headlights for a good while.
Take a shop towel and fold it into a small square. Dip the towel into the urethane mixture and make sure to get rid of any excess urethane from the towel. you don't want it to drip on the paint.
Begin applying the clear coat, starting at the top of the headlight and going in a horizontal movement, making your way down. Use the tape as guides, making sure you follow through with each stroke. Make sure you apply a nice thin coat, making sure there are no runs. After you apply, the clear coat will begin to become thick very fast, so try not to make any mistakes. Don't panic if you do. The clear coat will come off with mineral spirits. Just wet a shop towel with spirits and take all the clear coat off to start over.
You should get a nice, even coat on the headlights when you are finished. If not, take some spirits and strip the clear coat off and start over. The clear coat helps to add the finishing shine on the headlight, as well as seal up the headlight for protection.
Let the clear coat dry for 30 minutes before driving. After 30 minutes, the top of the clear coat will have become thick, and not so sticky. DO NOT TOUCH THE HEADLIGHT. The layer under the top is still wet. To be safe, let the clear coat sit for 4 hours before touching the headlight, Overnight is the safest bet.
If you didn't wash the car before applying the clear coat, I suggest not washing the it for at least a day, making sure that if you are to wash your car, you hand wash it. Urethane takes time to cure, so sticking your car in the sun to show off your headlights wont hurt. After about three days of sun exposure and curing, you are safe to wash the car as normal.
Congratulations. You have finished. you now have shiny, like new headlights and more importantly, you can see at night. You now have the expertise, and leftover paper to do more headlights (if you so feel).
SOMETHING TO NOTE: If you happen to notice that some of the urethane has come off (which may or may not happen over time. My first coat on my own car lasted about a year and a half, which, in between the time it came off and the time I noticed, no haze had appeared) feel free to make some more clear coat mix and put another layer on. While this solution may not be completely permanent, if done correctly, it can add years of haze free headlights to come.
I hope you found my instructable helpful, and I am here for anyone with any questions. Thank you.