After a few years of regular driving your headlights may become foggy and yellowed. Foggy headlights diminish the amount of light projected on the road at night and they become diffused. Diffused light shows less detail than non diffused light and can be a safety issue.
Headlights are made of a plastic that gets micro-pitted over time and what you want to do is remove all of those small perfections.
By using a restoration kit like the one in this Instructable you can restore your headlights to a crystal clear almost new state. Most kits are very similar and range in price from $10 to $30 dollars.
Step 1: Using Meguair's Headlight Restore Kit
Why? I use their products to keep all my car's naughty bits shiny so why not try their headlight stuff too?
Step 2: What's in the Kit?
In the kit you get a small bottle of PlasticX, a "UV protectant", a polishing wheel for a drill, a microfiber cloth, a sanding block, a disk of 1000 grit sandpaper, and a disk of 3000 grit sandpaper.
There are a couple more things you need that aren't mentioned on the box...
Step 3: In Addition to What Comes in the Kit...
You will need a glass cleaner, a roll of masking tape, and either a spray bottle of water or a dish of water to use with the sandpaper.
Step 4: Oh.
And a drill of some sort. The kit recommends a corded drill, but you can use a cordless. It doesn't take long to polish two headlights with the drill.
Step 5: What Am I Working With Here?
So my headlight isn't too too bad, but I want it to shine like new.
Step 6: Use the Masking Tape.
Be careful when taping to cover all of the painted surfaces around the headlight. Make sure the tape is stuck down good.
Step 7: Sandpaper Part 1.
Using the 1000 grit pad on the sanding block, wet the sandpaper and start sanding from side to side. Make sure you get all off the headlight. Use a paper towel when needed to clean off the mess to see what you have done. Once you have sanded enough, use the glass cleaner to remove the residue.
Step 8: Sand Paper Part 2.
Using the wetted 3000 grit sandpaper disk, sand the headlight in an up and down motion. Don't skimp on the water. Clean off the residue and your headlight should look uniformly fogged.
Step 9: Polish Time.
Start with a "nickle" sized dollop of polish on the buffing head. You don't need a lot of pressure, just place the buffer flat against the headlight and start polishing at the highest speed your drill uses. Add more polish if needed.
Step 10: Remove Polish.
Don't let the polish dry. Use the included microfiber cloth to remove the polish after you have finished buffing.
Step 11: Not Bad!
After wiping away the polish I noticed a couple of spots that could use a little more buffing. I repeated the buffing step with copious amounts of polish. Not too much though, you'll just end up slinging it all over the car and yourself.
Step 12: That's What I'm Talkin' 'bout Willis!
Much better after the second buffing session! This is what I was looking for.
Step 13: Protectant.
Not pictured: use a lint free cloth to apply the UV protectant. Once it hazes (I think it is just liquid wax) remove it with the microfiber cloth and you are done my friend! Well, half way done. You have one more to do.
Step 14: And Here Is the Other One.
Take a step back and compare the one you just finished to the next one. It should look like night and day.
Step 15: Fin.
My take-away from this is:
1. You don't need to buy a kit. You can pick up the sandpaper for a few bucks at your automotive store. I've seen similar small buffing wheels at the dollar store. The polish is regular ole PlasticX. I'm pretty sure the UV protectant is Meguiars Gold Class liquid wax.
2. Corners are a pain to get polished right.
3. Depending on your headlight damage you may need either 600 grit or 800 grit in addition to the 1000 and 3000. One of my headlights was more pitted than the other and even though it came out clear, it did not come out 100% smooth. Not a big issue but it could have used an extra bit of sanding.