Yellowing headlights & UV Protection

[AJones]

The plastic headlights on my T25 Avensis have been gradually yellowing and have some light scuffing/hazing, so ideally I'd like to restore them, if the restoration is likely to last at least a year or two.

I've found plenty of different guides on methods for sanding or polishing off the yellowed, oxidised plastic but that's when they all get a bit vague about how long the restoration will last, and what you should do to protect them from UV, to slow or stop them from yellowing again. Quite few suggest the headlights soon start yellowing again within a few months, some suggest coating the headlights, either with a short-term UV protection wax type product, other's suggest coating them with UV resistant clear seal sprays, either acrylic or urethane based.

I wondered if anyone had tried restoring their headlights, and whether you coated them with anything to protect them? And long did they last before they started yellowing again?

Thanks.

[frankie406]

I done mine with toothpaste  (actually works) then a good coating of high quality wax.you can also give it a clear coat

[valentino46]

As frankie  says toothpaste is the thing ..I used the gel type first.[ which  is a little bit more abrasive] ,followed by a normal whitener toothpaste . There is a demo on YOU TUBE .

[FROSTYBALLS]

Have a look at the following thread - 

 

[AV3]

Is the UV generated by the bulbs in use ? If so is it possible to exchange the standard bulbs for non halogen bulbs.

[FROSTYBALLS]

15 minutes ago, AV3 said:

Is the UV generated by the bulbs in use ? If so is it possible to exchange the standard bulbs for non halogen bulbs.

Usually halogen bulbs have a UV absorbing glass filter or a coating to reduce the amount of UV produced

[Konrad C]

My brothers Micra headlights have the yellow hazy look. He did the toothpaste trick and it worked for a while, but did not follow it up. The plastic is rough to touch. I tackled the headlights a couple of weeks ago, using cutting compound and a little water to smooth the rough plastic. Then polished the now smooth and clear plastic. Only a couple of days ago I used Nano Gloss on the headlights. I think the headlights need to be polish - actually the rest of the car needs to be polished being red - after every wash.

My T27 headlights are mostly fine except the upper surface which I polished. Never had issues with the glass headlamps of the old T22.

[TAuris]

I have tried the wet/sand method and it's effective, however you will never get the fine scratches out. The best and most effective way is to use a power tool. I have had very good results with Autoglym restoration kit. I did a final coat of clear coat, but there was too much moisture in the air and clouded up the following morning (Jan is not the best time). On a good hot day like now, the clear coat will dry completely or can be assisted with hair dryer / hot air gun / IR heater to make sure all the voltalite compounds have evaporated to give a glass finish.
 

Autoglym Headlight Restoration Complete Kit

 

[AJones]

19 hours ago, AV3 said:

Is the UV generated by the bulbs in use ? If so is it possible to exchange the standard bulbs for non halogen bulbs.

It's the UV from sunlight that's the problem - the articles I've seen online suggest that plastic headlights are manufactured with a protective UV-blocking outer coating, but this tends to wear away with age, exposing the plastic underneath which then turns yellow. You can sand and polish the plastic, to remove the yellowed outer layer, but a lot of the  articles suggest that this removes what ever is left of the protective coating and unless you apply another protective coating of some sort (UV protection wax/clear-coats etc) then your nice clear plastic will soon age and turn yellow again. 

Thanks for all the feedback and the link to the video on Youtube, it actually links to a load of videos about applying clear-coats, so perhaps I'll give them a polish and a clear-coat.

[Thermal]

I sanded and polished the headlights of my wife's Yaris.
Starting with paper 800, then 1000 then 1200 wet, I inspected the plastic for scratch marks with a magnifying glass and finally polished them with tooth paste.

TIP: Before applying the clearcote layer, put the lights on for a couple of minutes to pre-warm the glass, in order to avoid moisture.
Don't use a hair dryer because that injects dust into the fresh coating.  

This was done almost 3 years ago now, and the headlights still look like new.

[AV3]

On 15/08/2017 at 0:36 AM, FROSTYBALLS said:

Usually halogen bulbs have a UV absorbing glass filter or a coating to reduce the amount of UV produced

Thanks Frosty, I wasnt aware of this