How does headlight restoration work?

Joined
May 3, 2022
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I used one of those headlight restoration kits and it came out great, but I want to understand the reasons behind what I did.

The first step had me using these oxidation remover wipes and that made decent sense. You use the wipes to remove yellowing or other signs of hazing on the lights.

When I got to the sanding, it started to become confusing. You start out wet sanding with 2000 grit sandpaper and you keep going until the light looks uniformly cloudly.

After that, I had to switch to a 3000 grit sandpaper. I sanded for a minute with it, but what I don't get is what results I was looking for or even what the purpose of it is.

I then dried everything off and applied the clearcoat wipe. Somehow applying this made my headlight that was cloudy from sanding suddenly crystal clear. How is that even possible??

And why do I have to sand with multiple grit levels of paper? What does the 3000 grit do that the 2000 grit doesn't??
 
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The higher the number of the grit - the finer the sandpaper is.
A 600-grit will leave coarse heavy scratches, but is great for knocking down deep heavy oxidation quickly.
A 3000-grit leaves fine light scratches, but trying to sand yellow headlights with only 3000 grit will take 7-10 months per headlight.
3000-grit can easily be filled in with compound + polish, while same can't be done to 600-grit scratches.
img-120612154704.jpg

Lower number (coarse grit) is needed to break up the heavy oxidation and scratches. Kinda like chopping the tree down and clearing it from unwanted branches.
Then progressively higher number (finer sandpaper) is used to smoothen the deep scratched you just made. Kinda like taking the bark off that tree, and making a smooth splinter-free surface.
Once scratches are very light (after 2500/3000-grit usually) they are filled in with with compound (or sprayed with new layer of clearcoat). Similar to final sanding and staining of that chopped down tree.
Afterwards a polish is good idea. Similar to oiling or waxing the finished wood product.

Chart below only goes up to 2000, but same principles apply afterwards: the higher the number, the finer the sandpaper.
Sandpaper-Grit-Analysis-768x520.jpg


Don't know how much you know about wood working... Hope it makes sense. ¯\_(ツ)_/¯
 
Last edited:

Puhdantic

Thread starter
Joined
May 3, 2022
Messages
89
The higher the number of the grit - the finer the sandpaper is.
A 600-grit will leave coarse heavy scratches, but is great for knocking down deep heavy oxidation quickly.
A 3000-grit leaves fine light scratches, but trying to sand yellow headlights with only 3000 grit will take 7-10 months per headlight.
3000-grit can easily be filled in with compound + polish, while same can't be done to 600-grit scratches.
View attachment 106514
Lower number (coarse grit) is needed to break up the heavy oxidation and scratches. Kinda like chopping the tree down and clearing it from unwanted branches.
Then progressively higher number (finer sandpaper) is used to smoothen the deep scratched you just made. Kinda like taking the bark off that tree, and making a smooth splinter-free surface.
Once scratches are very light (after 2500/3000-grit usually) they are filled in with with compound (or sprayed with new layer of clearcoat). Similar to final sanding and staining of that chopped down tree.
Afterwards a polish is good idea. Similar to oiling or waxing the finished wood product.

Chart below only goes up to 2000, but same principles apply afterwards: the higher the number, the finer the sandpaper.
View attachment 106513

Don't know how much you know about wood working... Hope it makes sense. ¯\_(ツ)_/¯
Thank you for your explanation. How can you tell when you've sanded enough with finer grit sandpapers however?
 
Joined
Jul 10, 2022
Messages
272
I don't necessarily like to endorse products as I'm not selling them, but I used Cerakote and it costed $16.xx per kit.

I had a hard time deciding which brand to get and I relied upon reviews.

The results are phenomenal--I did one car last fall. The lenses are still clear. Car is not garaged.

I just did another car today. The 3rd part of the process is applying a ceramic coating.

In the past not on these 2 cars above, but on another, I simply used Comet cleanser. It looked good for a couple of weeks.

this process also was 1. wiping the oxidation 2. wet sanding by hand with two grades 3. applying a ceramic coat

No tools and great results, warranted for life. Everything is in the box, even gloves, and a hand buffer thingy to do the sanding with. Even if it oxidizes again, I'll do it again. I am 100% that 8 mos. later it's still clear on a car left outside...

Maybe this is what the new car dealer did, when I bought my car used in 2016. I would say 3 years later it started to show hazing again. So if it takes 3 years, I'm fine with it....
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IMG_6558.jpg
 
Joined
Jul 10, 2022
Messages
272
trying to offer a similar angle...I find that in the rush to take before and after types of pics and doing the jobs, the pics are not exact :)

But again the other car has been 8 months with headlights still clear, so even if it took 1-1.5 years to need the job redone, I'd sorta be ok.

With the used car I bought that was already 10, it took about 3 years for hazing to return (assumption is that car was done professionally but we'll never know with what product).

This one is worth the $16.xx imho....plus they say it's lifetime guaranteed and they'd send another kit....


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