Revisiting Headlight Repair (My successful how to)

There was a thread a while back on headlights and what and how to repair foggy or yellowed headlights.

I finally got off my but and took action on both my mustang and the expedition.

The history is I tried several of the repair kits with no joy. After reading up on things I decided that I would go the wet sand rout.

AUTO Zone sells a wet dry sandpaper kit that is perfect for this. It has 2-1000, 2-2000 and 1 2500 grit sheets all for about $3.00. I had a Mcgwire's headlight restoration kit with about 3/4 of a bottle of the polish in it so I used that and the buffing wheel that it comes with.

Step 1 Wet sand the headlight with the 1000 grit paper going over the whole unit at least 4 times in random vertical, up down, site to side. I try to end with a lighter circular sanding. Use a lot of water and rinse between standings. You should be dipping the sand paper in to the water at least 2-3x per time you go over the headlight. You know you are done when you feel an even resistance when sanding. Rinse and dry. Your headlight will look completely fogged. This is normal. The key is to look for any yellowing. If you see any sand some more in those areas feathering back to the areas that looked good.

Now go to the 2500 grit paper and repeat the process. Again going over the whole light at least 4x sanding as noted with the 1000 grit. Again you will start to feel a change in how the paper slides over the lens. IT will start out sticky needing a lot of water but should quickly become slippery. Once you get that slippery feeling over the entire bulb you are done.

Now I used the McGuire's kit but tossed the directions. I apply ALOT of polishing compound to the buffer pad. Drizzle it over the entire face. I probably used a heaping tablespoon. (the directions call for a teaspoon I think) Then (with the polisher / drill NOT TURNED ON) distribute the compound over the entire bulb. Then start polishing at slow speed. I probibly go over the whole light 2-3x with moderate pressure. I then gradually increas the speed and decrees the pressure. They key here is to use moderate force at low speed and as the speed increases you decrees the force to the point that only the weight of the drill is being applied against the bulb when you are at hight speed. Polishing takes a lot longer than you may think. Keep polishing until you have nothing left but a haze over the bulb but don't let it dry out completely. At this point you should be done. Wipe with a clean rag.

I was amazed at the results that this method gets. Total process takes about an hour for two headlights.

Anyway I just wanted to share a success story. I will probably re do them this spring and then apply clear coat to them but for now I am glad to be able to see at night again!!!

I just did the e36. Started out a little more aggressive with 600 >800>1000>1500>2000 and a quick polish - just used regular auto polishing compound. It was cold and I'm impatient - spent about 30 minutes for both fronts - weren't yellow - just hazy - now they're very clear. I had tried one of the kits previously - no where near as good or as fast as wet sanding and hitting it with the polisher.

WPWP.

I meant WPW(before and after)P.

oldtin wrote: I just did the e36. Started out a little more aggressive with 600 >800>1000>1500>2000 and a quick polish - just used regular auto polishing compound. It was cold and I'm impatient - spent about 30 minutes for both fronts - weren't yellow - just hazy - now they're very clear. I had tried one of the kits previously - no where near as good or as fast as wet sanding and hitting it with the polisher.

Mine were really yellow and foggy. The last attempt at one of the kits just made things worse. I was a bit scared to go to aggressive with the sand paper. This is why I started with the 1000. I also found that using a lot more polishing compound than you think you need was really the key. This lets you lean in to it more in the beginning with out damaging things I think in the past I have been to dam cheap with the polishing compound.

You may want to "clear coat" the lenses. I've done this in the past and they fogged right up again. I've heard this is due to the loss of some UV-protective layer on the outside. YMMV. All it took was some plastic polish applied by hand to get them back (when they fogged up after the initial sanding and polishing), but you'll have to do this regularly unless you find an effective coating...

Dragging this thread up again for a followup question.

Just hit my yellowed hazy headlights with 1000 grit followed by 2000 grit and the plastic polish.  Once the lens has been polished with plastic polish (I used PlastX because I had some laying around) can you just spray with clear coat or do you need to wash with soapy water or some other type of prep before applying clear?  I don't want to have to keep doing this every few months so I want to cover with clear coat, but I don't want the clear to not adhere due to the plastic polish.

IIRC after sanding is when you do the clear coat, hit it with another 2000 grit or higher wet sand, then polish.

And be careful to use polycarbonate safe clear coat!  Not all kinds are.

Duke said:

And be careful to use polycarbonate safe clear coat!  Not all kinds are.

 

OH, thanks for the heads up on that!

FuzzWuzzy said:

IIRC after sanding is when you do the clear coat, hit it with another 2000 grit or higher wet sand, then polish.

Do you mean spray with clear instead of polish?

What he means is that if you sand up to 2000 or even polish and then spray clearcoat, the clear won't adhere properly because the surface you're spraying it on is too smooth.  You generally wouldn't sand something any smoother than 800-1200 grit if you were trying to adhere another layer on top of it.  In the end you are polishing the clearcoat, not the plastic. 

The last 3M 'wipe on clearcoat' thing i used recommended to sand to 3000 before wiping on the clearcoat. It's definitely working, but it's not like i expect it to last for the 10-20 years that i expect the factory clearcoat on a car to last.

secretariata said:

Duke said:

And be careful to use polycarbonate safe clear coat!  Not all kinds are.

 

OH, thanks for the heads up on that!

So will it say it's safe for polycarbonate if it is or say it's not compatible if it isn't?  I just checked the can of duplicolor clear I got a couple of months ago and it doesn't say anything one way or the other... :(

In reply to Vigo :

Thanks for "clearing" that up! Pun intended...

In reply to secretariata :

Unfortunately the clear coats usually do not say if they are polycarbonate safe. You have to test it your self. Many are, a few are not.

I’ve used the 3m kit with great success a few times now. The polish is supposed to have some sort of UV protectant but that might just be a rumor. I always finished with a coat of wax. The headlights on my Mazda 3 in particular looked brand new even a couple of years after polishing them. 

Does clear coat yellow after time in the sun? 

I just did my Jaguar's headlights. I took the headlights out of the car and had really good results using a flannel wheel on a bench buffer with no abrasive of any kind for the final polish and the result is really impressive.

Isn't there a UV blocking wrap that you can use on the lights to prevent yellowing?

To give a specific clear coat recommendation, Spray Max makes a headlight-specific 1k primer/2k clear kit that is pretty much the best option out there to keep from yellowing within a forseeable vehicle lifespan. I've used it after 1500-grit sanding and it adheres like mad.  The clear has also been holding up well to Colorado winters (we like to toss down gravel for traction)

On the budget side, the 3M kits work very well and are typically a great deal on the 2-day shipping site, especially considering the Trizact discs inside usually cost more than the entire polishing kits.

On the budget side, the 3M kits work very well and are typically a great deal on the 2-day shipping site, especially considering the Trizact discs inside usually cost more than the entire polishing kits.

No kidding. It's quality stuff and regardless of what the instructions say you can easily stretch the contents over 2 cars.  ~$3.50 per car and you have a nice 3000grit pad left over. Almost free...