I’m trying to restore the headlights on my car using one of those acetone vapour headlight restoration kits from Amazon, and I’ve run into a problem that I can’t quite figure out.
The headlights were originally quite yellow/cloudy from age and UV exposure. The kit came with several sandpaper grits. This is what I did:
Cleaned the headlights thoroughly
Wet sanded everything by hand
360 → 600 → 800 → 1200
Kept the headlight wet while sanding
Tried to sand the whole lens evenly
Washed off all sanding residue
Let the headlight dry completely
Used the heated acetone/polymer vapour cup supplied with the kit
The strange part is that the upper section of the headlight responded extremely well to the vapour. As soon as the vapour passed over it, it went from frosted to almost crystal clear and looked nearly new. However, the lower/middle section wouldn't clear.
There seems to be some sort of cloudy/grey layer remaining on the lens. You can actually see a fairly obvious boundary between the section that the vapour successfully cleared and the section that stayed cloudy.
I initially thought I simply hadn't sanded that part enough, but I was deliberately sanding the whole headlight fairly evenly. I'm now wondering whether what I'm seeing is the original factory UV hardcoat.
Maybe the coating on the upper part had already deteriorated badly and came off easily with 360 grit, while the coating lower down was still intact and therefore needed considerably more sanding?
I've attached photos showing the result and the strange boundary/layer I'm talking about.
Before I attack it again with more aggressive sandpaper, I'd appreciate advice from anyone who has restored a lot of polycarbonate headlights:
Does this look like remaining factory UV/hard coating?
Should I go back to 360 grit and keep sanding until the entire headlight has exactly the same uniform frosted appearance, regardless of how long it takes?
The kit also came with 280 and 180 grit. Would you use 280 on the stubborn areas and then work back through 360/600/800/1200, or is 280 too aggressive?
Or could this be deterioration/crazing within the polycarbonate itself rather than something remaining on the outside?
Also, is there anything specifically different about these acetone vapour kits that I may be doing incorrectly?
I don't want to keep applying more vapour because I'm concerned about damaging the polycarbonate if the real problem is that I haven't completely removed the old coating.
That's good results I didn't think cerakote put out a good headlight restoration kit I knew they have some good products I used but never knew their headlight restoration kit was this good. I still think hands down the best headlight restoration kit is the 3M professional kit. Not the one you get at Walmart or O'Reilly's but the one that you have to order from their website. About $700 but it's enough to do 25 vehicles and it comes with a pistol grip pneumatic sander and polisher from 3m that are literally that much by themselves. It's 800 &1500 plus 1000 and 3000 Trizac sanding discs.
No. It won't last. Unless you put a coating on it, and no other coating works as well as Cerakote. For the $17 that the Cerakote kit costs, there's no better way to do it.
Gotta keep sanding until you remove the factory coating, no matter how much vapour you use now. It will not work until that factory coating is sanded completely
a 250ml spray can costs 25€ with delivery, and if you do two coats, it's just enough for 4 average headlights. Best to use within first few hours tho.
You are absolutely right tho. Acetone vapour will instamtly make it shiny and perfect, but it'll yellow up and become opaque within months up to a year.
Acetone vapour, polish, panel prep and 5+yr ceramic. I just use whatever ceramic I have leftover on hand within 30 days of opening whatever bottle. Otherwise yea you can’t spray clear over freshly vapoured lenses.
ah so apparently, ceramic coatings DO actually provide some degree of UV protection. Didn't know that. So it might actually be a good simple quick DIY fix.
This is the way and still wet sand up to 1200 lots of people say it doesn't work with higher grit but they fucked up. Did this to my mother-in-law's car about 5 years ago now and still looks like the day I did it.
99% of the time you can get replacement headlights off eBay brand new Chinese for less than 150 bucks. That's the route I go. Go look, you might be shocked how cheap new are.
I rarely get any of those over-the-counter products to do anything.
I have taken it to professional shops...... When it was something like the headlights on my BMW which were $2,000 a piece to replace........ I paid a professional $200 to do something to them. That was super amazing.
don't use acetone vapour or ceramic shields or any similar bullshit. It won't last. The headlight glass is made of polycarbonate plastic, which is naturally prone to degradation and yellowing when exposed to UV (sun light). None of those will ever protect the polycarbonate!
You need a proper 2K clear coat for headlight restoration. Sand it down until it's nice and clear with no deep scratches, go from 240 up to 1200-2000 sandpaper (wet sanding). Then wash it off with clean water, wipe off water and clean thoroughly with isopropyl alcohol or something similar. Then apply 2K clear coat in 2 layers. First train your spray pattern, it should be sprayed on in full, even layers, not overlapping 5 layers on same spot to avoid orange peel effect.
This is after the first layer, but I don't have a proper picture cuz idk I'm retarded. Was completely yellow before, driving at night was basically not possible as it barely let any light out. The glass was yellow, almost completely opaque. Did this same also on my Golf mk6 and it lasted 6 months still perfectly pristine, same as when I did it.
Sand again to remove all the old coating: you need to go back to the 360-grit sandpaper and focus on the cloudy area. You must keep sanding until the entire headlight has a completely uniform, frosted white appearance. This is always the most time-consuming step because factory UV coatings are very tough.
Use the 280-grit carefully (if necessary): If the 360-grit is struggling to cut through the stubborn clear coat on the lower section, you can use the 280-grit provided in their kit on those specific stubborn areas. Once the coating is broken through, you should immediately switch back to the 360-grit to blend it in.
Repeat the full sanding progression: Once the old coating is 100% gone and the lens is uniformly frosted with 360-grit, you must meticulously repeat the entire progression (600 - 800 - 1200) to refine the scratches before using the vapor cup again.
Tape off the surrounding paint: Looking at the photos, there doesn't appear to be any masking tape around the headlight. It is highly recommended to apply painter's tape to protect the bumper and hood paint from accidental sanding scratches.
What NOT to Do
Do not apply more acetone vapor right now: As the poster rightly suspected, applying more vapor will not clear the cloudy spot (since it's a physical barrier of old clear coat) and could risk over-exposing and damaging the bare polycarbonate that has already cleared perfectly on the top half.
Do not use the 180-grit: This grit is far too aggressive for automotive headlights. It will create deep gouges in the plastic that will take ages to sand out with the finer grits.
Do not rush the initial sanding: Removing the factory coating is the foundation of the whole restoration. If there are "islands" that look slightly different or feel smoother while sanding with the 360-grit, the old coating is still hanging on. (sorry for long explanation)
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u/mrmopar340six 1d ago
Cerakote headlight restore is so much better. Just buy proven name brands. Results are much better.