Headlight restoration problem

[luvsspeed]

I was trying to correct a previous restoration and it has made the problem worse. What would cause a type of haze to appear on the inside of the lens, from sanding on the outside?

[IMG]20190804_143024 by jay will, on Flickr[/IMG]

[IMG]20190804_143016 by jay will, on Flickr[/IMG]

[Turbo510]

We have industrial-strength Isopropyl alcohol for some cleaning at work, and that's what I used on my headlights when washing the insides. After removing all bulbs, about a cup of Alcohol went in. A few minutes of sloshing that around, and some shaking to splash off the reflectors, drain it out. A blow drier helps to evaporate remaining fluid and get the vapor out, but I wouldn't use a hot setting. With the outside of the lens polished, it looks like new. Periodically I use white polishing compound and a rag to keep the surface fresh and clear, followed by a coat of wax.

[Kevin C]

If you can get the insides clean I have found that a coat of Duplicolor clear keeps the lenses from yellowing.

[old guy]

Be very careful with the isopropyl alcohol inside the headlight. I tried it and it bubbled up the black coating inside the light. replaced the lights as a result.

[2004a4b630QT]

Are you sure you sanded down far enough? That might still be on the outside

[EuroxS4]

I would say either its in the plastic itself or it when it was sanded it was not done properly or not enough.When you wet sand the lenses you want to make sure the're uniformly matte. If you see any nice clean non matte spots you need to redo that area as you didnt get all the old uv coating off.Normally sanding head light you want to go from left to right or right to left nothing else.Wet sand of course with 600 grit paper. Then clean the lens really well. Then spray or clear over it or polish the lens with extra steps and compounds. Hard to tell from the pictures but it is possible that there is something inside the headlight if it wasnt sealed properly or had a missing cover.

[luvsspeed]

I thought it was on the outside as well, but it is a smooth as can be. I used a 3m kit, which did not say anything about wet sanding until the last step. I used this kit on another truck with no issues.

[Deerhurst]

I've got one light on my wagon that has some oddness too. I've had lights in the past that were so UV damaged and abused that they were yellowed and nasty all the way through. Had to buff the inside and the outside. A light solvent on the inside could help. Could be as simple as moisture was inside and got burned off by the headlight bulb heat and left a residue on the inside. Too bad it's hard to just buy the lens.

[luvsspeed]

Now shouldn't that have been visible before I started sanding?

[Deerhurst]

Not necessarily. If it's oxidized on the outside you may not be able to even see the thin film later on the inside. Hell, could be a film deposit from the paint they use on those orange light bulbs.

The ones on my former Sentra were so bad I couldn't see how bay they were until I cleaned out the top layer and pulled the headlights apart.

[luvsspeed]

Are you sure you sanded down far enough? That might still be on the outside

I sanded down more on these lights than on lights worse off. I was afraid of going to deep.

[2004a4b630QT]

I sanded down more on these lights than on lights worse off. I was afraid of going to deep.

The youtuber "Ratchet and Wrenches" has an in-depth video on the different ways to do it. The one where he dry sands, wet sands, and clear coats is the one I want to do, and he removes a lot of material and starts with a lower grit than most diys. You might want to check it out as a guide to how far you can go.

I would sand and polish again. You've got nothing to lose if the lens is discolored all the way through anyway. I would guess you're simply not through the oxidation yet.

[luvsspeed]

The youtuber "Ratchet and Wrenches" has an in-depth video on the different ways to do it. The one where he dry sands, wet sands, and clear coats is the one I want to do, and he removes a lot of material and starts with a lower grit than most diys. You might want to check it out as a guide to how far you can go.

I would sand and polish again. You've got nothing to lose if the lens is discolored all the way through anyway. I would guess you're simply not through the oxidation yet.

Your rite. I will try some more on weds. This is the kit that I used https://www.amazon.com/3M-39008-Head...95993833&psc=1

[2004a4b630QT]

One thing that youtuber mentions that you shouldn't polish before clear coating. He stops sanding at 1200-1500 grit to "key" the plastic so the clear adheres. Then after clear, wet sand to remove orange peel and polish.
Clear doesn't adhere well to a smooth surface which is why using it on its own is considered temporary, as are all paint spot repairs where the clear is blended new into old. Nature of the beast.

Fixing the lenses is a lot of labor and the clear will peel or oxidize again but it was take years. If you skip the clear and just polish and protect with wax it won't last at all. This is why many opt for a cheap (relative) replacement headlight unit instead.

[luvsspeed]

Are you sure you sanded down far enough? That might still be on the outside

I felt the lights today. Where it is hazy its smooth as wax and where it's clear is grippy smooth. So I guess I didnt sand enough.

[luvsspeed]

Well I sanded some more and got it to about 85%. As I was sanding I noticed a bondo type pattern and the more I sanded the more it went away, so there was a lot more coating left. A kit and a half and I got one headlight to about 85%. Well I guess that's what happens when the roughest grit is 500 in the kit. Now I don't know if the inside of the lens are damaged as well since the inside still looks hazy, or if it could be cleaned out with alcohol. Will 91% isopropyl alcohol damaged the chrome inside the lens or anything else?

[old guy]

Well I sanded some more and got it to about 85%. As I was sanding I noticed a bondo type pattern and the more I sanded the more it went away, so there was a lot more coating left. A kit and a half and I got one headlight to about 85%. Well I guess that's what happens when the roughest grit is 500 in the kit. Now I don't know if the inside of the lens are damaged as well since the inside still looks hazy, or if it could be cleaned out with alcohol. Will 91% isopropyl alcohol damaged the chrome inside the lens or anything else?

Clicky click®


EDIT: A visual may help ;-)

[oaybar007]

I've had a similar issue ever since I tried to restore my headlights many years ago. No matter how much I sand, polish, etc. the lights will always redevelop the yellow shade in a few weeks. They'll look fine right after restoration but will always go back. These days I just keep a bottle of Meguire's PlastX and just hit the lights as needed. What I really need is a powerful corded drill to go at these lights. I think it's the same issue, simply not getting at the material enough with proper grit, technique and heat.

[Kevin C]

The original coating on the lens prevented them from yellowing, over time it fails. Once you sand it off your down to the original plastic that yellows very easily. That's where a coat of clear acrylic paint help, on my B5 the headlights looked perfect after three years.

[luvsspeed]

I have bought a product called opti-lens, which is supposed to prevent that from happening

[luvsspeed]

Well I read up on cleaning the inside of headlights and quite a few sites recommend cleaning the inside with Methanol. I figured I would give it a shot. https://5series.net/forums/e60-discu...lights-137264/

[Turbo510]

Clicky click®


EDIT: A visual may help ;-)

I'll take your word for it that IPA did that to your headlights, so maybe your housing material was different than mine. That damage looks like something that Toluene or MEK would do.

[old guy]

I'll take your word for it that IPA did that to your headlights, so maybe your housing material was different than mine. That damage looks like something that Toluene or MEK would do.

91% isopropyl alcohol. It surprised me too. I first swirled around some general purpose cleaner and rinsed with distilled water. It reduced the film on the inside a little. So I figured I would try a little IPA. You can see the results:-(

[oaybar007]

The original coating on the lens prevented them from yellowing, over time it fails. Once you sand it off your down to the original plastic that yellows very easily. That's where a coat of clear acrylic paint help, on my B5 the headlights looked perfect after three years.

Thanks for explaining this. I never realized that.

I'm going to have to try to refinish them again soon and spray clear to finish them.

[luvsspeed]

Well I got my methanol today and tested it on a spare set of ecodes that I have. It was completely safe for the black and chrome finishes. It will help you clean out the loose and surface dirt, however it will not remove any grime or haze without physical help. As you can see from the picture the cleaned vs. the uncleaned portion. You can only get so much clean with removing the projector. I'm open to ideas for cleaning the rest of the lens. I was thinking of using a strong magnet wrapped with cloth.

[IMG]20190814_193838 by jay will, on Flickr[/IMG]

[2004a4b630QT]

I thought there were a few diy's for removing the lens with a heat gun. It would also give you a chance to re-seal the lens to the housing preventing further leaks that caused the inside to oxidize.

[luvsspeed]

I thought there were a few diy's for removing the lens with a heat gun. It would also give you a chance to re-seal the lens to the housing preventing further leaks that caused the inside to oxidize.

I've done that on a previous car and it was a pita to get it to seal correctly afterwards. I would not want to chance that on these.

[Deerhurst]

I've always used the oven to remove and reseal headlight lenses. Granted, nothing Audi before. Works like a charm. I always do a dunk test to make sure they are sealed.

[john_gonzo]

The original coating on the lens prevented them from yellowing, over time it fails. Once you sand it off your down to the original plastic that yellows very easily. That's where a coat of clear acrylic paint help, on my B5 the headlights looked perfect after three years.

Yes! Gotta replace the sealant that was sanded off. I've used a 50/50 mix of mineral spirits and Minwax Helmsman Spar Urethane Clear Gloss varnish on several sets of headlights (Audi and non-Audi) and they have all stood up well to the Florida sun.

Here's the blurb from the DIY I followed:
"Unfortunately all that work will quickly be undone if the fresh surface is not protected, and while you can use wax to help, the best solution is to apply a UV sealant like the lenses had from the factory. Most sealants are not available in Canada due to environmental regulations, do I chose to follow the recipe in the above thread to mix mine own from a 50:50 ratio of Miniwax Helmspar Clear Gloss urethane-based varnish and mineral spirits. You don't need to mix much sealant, 3 tbls of helmspar and 3 tbls of mineral spirits was way more than enough to do these lights."

"The application was relatively simple, a very thin coat of sealant applied over the entire lens surface following a through cleaning with raw mineral spirits. I used a blue shop towel folded down to a 1.5" square as an applicator pad. Basically you want to soak the end of the applicator in the sealant almost to the point of dripping then wipe it across the lens in even overlapping strokes. I did take several attempts to perfect the technique, but the sealant is very forgiving and is easily removed with mineral spirits if you make a mistake and need to start over."

Source: DIY-Headlight-restoration-walk-through

[luvsspeed]

Well at this point I am open to ideas. I still have not been able to remove the film from inside. It almost seems like an burnt oil film. I got about 25% of it off. The methanol helped but lacks dissolving power. I used isopropyl alcohol with no luck. I even mixed dawn with the methanol which helped, but still did not remove it. Were I can get my hand after removing the projector is fine, its just where I can't get my hand.