way to restore yellowed headlight lenses?

[Aerodynamica]

Ok I recall this was covered once before but I can't recall who gave the solution! Russ maybe?

There was a trick to leaving the lenses outin the sun after first applying some stuff to them but what was it?

[White Exec]

Hi Graeme,

Sunlight alone won't do it - it's the UV that created the yellowish tinge in the first place, from the bromine compounds in the plastic (see Wikipedia, etc.).

Yellow-brown layer is at the surface, mainly, and needs physically removing.
Start by thoroughly cleaning both sides with Mer/Brasso/TurtleWaxHeadlightRestorerCreamCleaner or similar.
This will obtain quite a bit of improvement.
If insufficient, various chemical cleaning routines are listed on the web.
Other members will have their own remedies.

Stick with good quality branded (UV blocked) headlight bulbs to minimize further damage, eg Philips or Osram.

[russ92xmsed]

'Twas me Graeme. I used both Vanish and oxi clean stain remover on them now. I found the oxi clean slightly better. Two to three scoops in a white ceramic dish and left in strong sunlight for a day. Flip them over now and again. You should find the water has turned yellow. I did try it at night, and it didn't work, so the sunlight does help with the reaction. Two soaks should do it, then a good polish. I found t cut and then car polish worked. But also wash it all off incase and buff up with a microfibre cloth.

Will...Dieselman... Was telling me about his polishing method at the national. It's a case of use at your own risk. But it worked. I would ask him for details.

[dollywobbler]

Must concede, I went for the easy option and fitted some Osram nightbreakers. A staggering difference to dipped beam (didn't bother with the mains, as they're good enough anyway).

[Dieselman]

You will be amazed at the difference a clean of the reflectors makes. Not only does it make the lights brighter, it gives noticeably better cut-off and sharpness.

[Aerodynamica]

Haha thanks! It's not for me but a friend with an older Passat whose lights are a bit milky. I wonder if this method can work for them too? I'll tell him to give it a go..

[White Exec]

Oh...thought you were talking about XM internal fresnels!
If it's just outer plastic lenses that have yellowed, then Mer/TCut will do the job easily.
Have just Mer'd our RAV lights, and they look almost new.
Simples.

[russ92xmsed]

Yeah, don't start taking any old headlights out and soaking them....

[southerner]

try vinegar

[cxprestigeauto]

Depending on how much the plastic has degraded: If very bad (and I have seen some very poor Passats) then you may need to use fine wet and dry to remove the outer layer of degraded plastic. Then simply work back with finer cutting agents Farcela G3/T Cut until you are simply applying a UV protective polish/coating. The results are brilliant

Rob