Polish those headlights! (Pic heavy)

Probably one of the simplest 'upgrades' on a slightly older car is to polish up the headlight lenses and recoat them.

Time and again, Scheinwerfermann has said to get the kit from DoubleHorn Products, and the Allpar forums has their own photoessay on using the kit.

Here's my own results on a 2001 Corolla LE, mostly garage kept:

Let's start with the left headlight turned on to the high beam position. Eww.


Moving on, some closeups of the light turned off:



Notice the top edge of the lens is really hazy from UV exposure here:


Here are the lenses scrubbed up with the rough side of the included sponge and using their cleaner, keeping the lens wet while scrubbing:

I ran wet fingers across the lens here, otherwise it looked like the left one but less heavily scrubbed:


Then the right hand polished:


Then closeups of the left one after being sprayed with the protective coating



I'll add another "on" pic of that left headlight light tomorrow.

Let me be the first to tell you that while I'm extremely obsessive compulsive about "doing things right", I'm also strangely lazy. I'm sure other people are much more patient than I am when doing a project like this, yet despite my impatience the results are excellent.


Because this is pic heavy, be nice to your fellow CPFers and *don't* quote the images when quoting me in replies.

I polished my headlight awhile back but didn't know there was stuff to coat it with perhaps UV protectant that would make it so I wouldn't have to polish it every 6 months from fading.

Fantastic writeup and pictures!

Lynx_Arc, that's exactly right -- what you polish off when you scrub them is the hard coating applied at the factory to make the lenses withstand abrasion and UV. Once the base plastic is exposed, the deterioration comes back much faster and more severely. There is no wax or wax-like "apply-and-wipe-off" type of sealant that can protect the plastic lenses; you have to reapply the paintlike hard coating, and it has to be the right kind of coating material.

I need to find some clear uv paint for plastic then, wax doesn't last very long maybe 3-6 months around here due to the heat and cold temps

Maybe some of that clear bra stuff would work?

I used a kit...can't recall which one...to polish the lenses on a '99 Toyota Avalon. They both came out nice, but 8 months later the drivers side still looks perfect but the passenger side is back to yellow. I wonder why the difference? Perhaps I took more material off on the passenger side and left it more exposed...or perhaps it was an older lens to begin with. On a used car, you don't know what has been replaced before.

I can buy a new headlight off ebay for about $50, so a kit costing over $20 would not be worth it to me. I miss the day of sealed glass headlights where you replace everything. Now the bulbs cost as much as whole sealed beams do and the plastic lenses go bad on you this is backwards in technology lol.

Lynx_Arc said:

I can buy a new headlight off ebay for about $50, so a kit costing over $20 would not be worth it to me. I miss the day of sealed glass headlights where you replace everything. Now the bulbs cost as much as whole sealed beams do and the plastic lenses go bad on you this is backwards in technology lol.

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The best price I can find, for an Avalon headlight assembly is $150 bucks, and I suspect that is an aftermarket assembly of dubious quality. Will the reflectors work as well as OEM...or will they be like typical copied products and just be "close"...yielding a poorly focussed beam? I would probably be better off with the yellowed OEMs! OEM headlights are closer to $250 dollars and probably have been sitting around for 10 years. Not sure how well they were protected from ozone during those years.

Scheinwerfermann said:

...you have to reapply the paintlike hard coating, and it has to be the right kind of coating material.

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Wonder if something like this would work...at very least it would have to be applied very evenly and polished to keep it from effecting the optics.
http://www.levineautoparts.com/upclear1uvre.html

Disaster said:

The best price I can find, for an Avalon headlight assembly is $150 bucks, and I suspect that is an aftermarket assembly of dubious quality. Will the reflectors work as well as OEM...or will they be like typical copied products and just be "close"...yielding a poorly focussed beam? I would probably be better off with the yellowed OEMs! OEM headlights are closer to $250 dollars and probably have been sitting around for 10 years. Not sure how well they were protected from ozone during those years.

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You're right to be wary of the aftermarket "just like OEM" headlights. If they're not OEM, they're not "just like OEM". This .PDF is an eye-opener.

I'm not sure ozone has as deletorious effect on headlight assemblies as UV does.

The spraycan you linked to is $19.99 +shipping. The complete DoubleHorn kit is $29.95. Maybe shipping is less than $9.96, but I'd say the complete kit is a better deal.


I have noticed what appears to be fine cracks all throughout the headlight lenses now... Were they always there and I couldn't see them before, or did I press too hard while polishing? Or maybe it was that it was pretty cool out (below 50F) when I sprayed them?

I have so much of the kit left that I could just scrub them back down again...

Update: Here's a link to the just-sprayed left headlight in the original size.

Random yet related thought

Maybe I've said this publically before, but it some time ago occured to me that as headlight lenses yellow, reducing their ability to pass blue light, those blue light bulbs, which are already abysmal, get even worse. After all, they've reduced the amount of yellow light emitted at the bulb, and the lens reduces the amount of blue light emitted-- so now the total light emitted is far lower than ever before.

Just a bit of musing...

Lynx_Arc said:

I need to find some clear uv paint for plastic then, wax doesn't last very long maybe 3-6 months around here due to the heat and cold temps

Click to expand...

Pay attention. The Doublehorn kit contains the correct material.

I can buy a new headlight off ebay for about $50,

Click to expand...

Aftermarket lights are trash, right out of the box.

Scheinwerfermann said:

Pay attention. The Doublehorn kit contains the correct material.



Aftermarket lights are trash, right out of the box.

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I don't need all that stuff in the doublehorn kit, only need the paint as I have sandpaper and plastic polish.

Re: Polish those headlights! (Pics added)

Here's the lights the next day illustrating the "cracks". Lenses are now wet and dirty as it started raining earlier when my wife drove the car home.



And here it is lit. I'm guessing white balance comparison between yesterday's pics and the day before will be difficult because it was overcast and rainy yesterday; still relatively clear the day before. Still, it should illustrate the difference between the clarity of the lamps.



Scheinwerfermann: Do you expect the crackling will be a problem for oncoming drivers, or should I not be extremely worried?

Maybe it's not crackling in the lenses-- maybe it's crackling in the spray due to some of the micropolishing compound not being totally cleaned off and the lenses also not being absolutely dry before spraying (I thought I'd cleaned it off well enough and the lenses had dried sufficiently).

Can't tell for 100% certain from these pics, but it looks to me as if the lens itself -- the actual polycarbonate -- has crazed with age, heat, and UV exposure. The only way to tell for sure would be to remove the coating and check again. These craze marks will have the same effect as surface pitting: more glare/stray light. Are they bad enough to worry about? It depends on how much you care.

Thanks for the response!

I *do* care that it could cause some glare for other drivers; I rationalize that surely it's less now that the hazing itself has been removed.

I suppose that the original anti-UV coating of the lens was mated to the surface such that it wasn't apparent that the crazing was there, and stripping it revealed it. I may be able to just polish down further into the lens as it may yet be on the surface, not deep enough such that removing lens material will just go through to the other side or even substantially weaken the lens.

Doing the A/B comparison here (I'm allowed to quote my own pics )



(Full size pic links before and after)

Odd. I sure hope I didn't crack it getting overexuberant with scrubbing/polishing by pushing too hard and flexing the lens.

Well, I don't know how hard you pressed/flexed, but yes, crazing of the type we see here will definitely result from flexure of polycarbonate, and the amount of flexure required to cause it gets lower as the material ages and goes through thermal cycles, UV exposure, etc. So if you really threw muscle into polishing these lenses, it's possible you might have caused or aggravated the crazing. This kind of appearance does not result from applying a coating of this nature over not-entirely-dry substrate.

I still remain unconvinced that plastic of any kind is really the best choice of material for headlamp lenses.

Actually, there are several plastics that would make ideal headlight lenses. Alas, manufacturers don't want to pay for them, since these sorts of polymers are NOT cheap. Really pure polycarbonates, like those used to make CDs, really clean PMMA, et al, would survive a LOT better than what's being used today. But at 5X the material price, trickier processing, etc., no one wants to go this way.

Scheinwerfermann said:

I still remain unconvinced that plastic of any kind is really the best choice of material for headlamp lenses.

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I am not 100% what cause the cracks on your headlight lens but i have seen it on other cars regardless if they have been polish or not.

Kuryakin said:

Actually, there are several plastics that would make ideal headlight lenses. Alas, manufacturers don't want to pay for them, since these sorts of polymers are NOT cheap. Really pure polycarbonates, like those used to make CDs, really clean PMMA, et al, would survive a LOT better than what's being used today.

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CDs are ridiculously easy to scratch. It doesn't take much to break them, either.

If I had my 'druthers, I'd take glass over any of the plastics the automakers have been cursing our headlights with.

glass headlights were not as sexy but there was zero maintenance and replacement costs were nothing compared to this plastic stuff. I almost think they did this to sell more parts because it doesn't make a car any cheaper.