View Full Version : Glass fog light restore

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A4 1.8tqm
01-06-2010, 08:11 AM
After installing a 6000 K. HID headlight kit my friend got me for Christmas, the stock fogs on my '99 A4 were looking pretty dull by comparison. I considered buying new ones but decided to at least try and restore them first. The only thing I could think of was to fill the chips by spraying clear coat, wet sand and polish to a nice clear surface, but will it work?

Here's a couple of before pics-



First thing I did was give the entire lights a wipe down with Megs APC+ to remove any loose debris. Then the glass got scrubbed with a brush and IPA, wet sanded with 2000 and then re-brushed with IPA to ensure a clean surface for painting.

The one on the left is after one coat of clear, unsanded.

Here is a close-up of the first coat. Many of the small pits are filled in, hopes are high.

After a second coat It got a light wet sanding with 800 grit. I used a soft block with "single swipe" sanding, back and forth just felt too aggressive. Then more light sanding with 2000 grit.

Here is a third coat, sanded with 800 then 2000

Before and after, the final coat applied but unsanded (After finishing the other one I left them to cure over night before polishing).

Did you notice the Sonicare tooth brush in an earlier pic? Immediately after each coat of clear I took the vibrating toothbrush and pressed it to the light's housing, in various places and pressures. The goal being to shake any air bubbles out so the clear can completely fill the pits. I just did this cause I thought it was a good idea. This next pic is the one time I forgot to "vibrate". It dried looking like this and I ended up peeling the clear off, re-prepping the surface and starting from scratch. :doh:

Here they are the next morning after 800, 2000, Menz power gloss, Menz IP then 3M Ultrafine.




The big question is how will they look next week? Six months? A year? Only time will tell, but I happy for now!

Matt S.
01-06-2010, 10:49 AM
Wow, very impressive results!

Do you do body work for a living? What did you use to spray the clear and what kind did you use? Just curious...thank you for sharing! I never would have thought glass could be filled in like that.

Mike Phillips
01-06-2010, 11:15 AM
Keep up posted...

Glass lenses would solve the problem but the entire industry has switched to plastic.


A4 1.8tqm
01-06-2010, 05:39 PM
Thanks for the reply's guy's. No I don't do body work for a living, I record events to video and sell the DVD's, LOL. I used U-POL clear in a rattle can, the same stuff from my bumper's "deep scratch repair".

I'm sorry Mike, I don't quite follow... These are glass, what would glass lenses solve? Thanks.

I will keep this updated though. I'm very curious how long it will last, with all the crap I put my car through who knows.

01-07-2010, 06:20 PM
Nice work!

01-07-2010, 07:06 PM
One of my wifes headlamps discolored and had them repaired under warranty. They did just that, removed the lamps, polished, and then clearcoated. They suggested it was for UV protection. Held up over a year.

Becareful with HID aftermarket kits, still illegal as far as I know as DOT doesnt approve of them. Problem often due to cutoff angles and diffusers which are not included in non-HID lamps.

A4 1.8tqm
01-07-2010, 08:38 PM
Thanks Turbo! :xyxthumbs:

Killr- Were your wife's headlights plastic or glass? Just curious.

Honestly, I didn't know all aftermarket HID's were illegal, I thought it was just the high color temps. Thank you for the warning! I do understand about diffusers and cutoffs. Once I had them installed I was sure to align the cutoff properly, as they were quite obviously off. Now, when driving on level ground the cutoff is right on the streets horizon. I was reluctant about HIDs at first because of all those people who put 10,000-12,000 K with in a headlight without projectors and remove the diffusers. The exposed bulb makes for a blinding on coming pass. Don't worry, I'm not "that guy" LOL.

01-07-2010, 10:32 PM
I thought my 2001 Audi A4's fog lenses were plastic. However, they look just like yours. Maybe the switched to plastic for my model year.

Either way, nice recovery. Mine were pitted so I wet sanded and polished them back up.

01-08-2010, 07:10 AM
I think the title says "GLASS" fog light restore

great job, awesome write-up....looks like new

01-08-2010, 09:45 AM
HID's in a non HID housing are illegal. It order to be legal you need a projector that has a defined cutoff line. Many cases it takes a full retro to do this and around $250-400 to accomplish. HID's look cool, but are pointless in fogs. Fog lights are meant to have a short throw and wide. HID's in that housing only makes more glare for on coming drivers. Don't get me wrong HID's between 4300-6000k produce amazing light and look cool, but I hate the glare and hot spots by other driver's who just put in a PNP (plug and play) kit and don't care about others. If you live in a rural area fine, but in Southern, CA we have these clowns all over the place. I am in the process of doing a retro for my 2005 Tacoma. I will post pic's when I am done.

A4 1.8tqm
01-08-2010, 08:29 PM
Oh I didn't put the HIDs in the fogs, LOL. You can see the bulbs in the pics. I agree about people w/ PnP kits who don't know what they are doing, see my previous post. Great info though! I'll do a quick write up on the HID install.

Thanks for the compliment Impressions!

01-08-2010, 09:35 PM
Killr- Were your wife's headlights plastic or glass? Just curious.

plastic ... I believe its actually Lexan that GM uses.

A4 1.8tqm
01-08-2010, 09:56 PM
Cool, I was thinking about shooting a few coats on my headlights. I'll have to see how the fogs hold up first though.

01-22-2010, 11:44 AM
What a day and night transformation. Wow! Great Work. They look great. I'll definitely be saving this thread.

A4 1.8tqm
03-12-2010, 07:22 PM
Another thread reminded me of this one and I figured I should update the results. Since the restore on 1/3/2010 I have not payed any special attention to the fogs, I driven on snowboarding trips and regular daily commutes in crappy Wa. weather. Here is what they look like, I just went out to take this pic a moment ago, 4:18pm 3/12/2010.
Edit: forgot to post the pic. LOL

A few dings, as expected, but still lookin good! :D