Yellowed Lens on Sturmey-Archer Headlamp
 

I have an old, decrepit SA headlamp from the old country, with a yellowed lens. I want to clean it up. I've been searching for awhile, but I can't find it. A while back someone mentioned a product they used to clean and polish up old, foggy, yellowed Headlamp Lenses. rhm, I'm looking in your direction...

If the lens is plastic, you want one of the polishes sold for acrylic automobile headlight lenses/covers or aircraft canopies. But all it will do is remove the surface scratches and discoloring; if the discoloring is all through the lens, I don't believe there's any way to clean it.

Well, I don't have a magic product either, and like JML says, I don't think you can change discolored plastic back to clear. But I have cleaned up a couple of those Sturmey Archer lenses with pretty good --not stellar-- results. In both cases the plastic had yellowed and developed a patchy kind of frost.

If I recall correctly, I sanded the whole surface of the lens with superfine sandpaper --you can get 1000, 1500, even 2000 grit at an auto parts store-- until all the frosting and scratches were gone. Do this in a sink full of soapy water. Then I polished them with polishing compound --also from the auto parts store. In the end I think I also polished them with wax. The stuff JML mentions sounds like a good idea, but I haven't tried it. An acrylic clearcoat might be a good idea, but I haven't tried that.

I did that with one of those older plastic ipods. It was so scratched up you couldn't read the screen but it sanded and polished up really nice.

I've used Novus' polish system to remove scratches and surface fogging, but as JML suggests, it may not remove the yellowing. It may be yellow, but it will be yellow, shiny, and transparent!

I have a couple NOS lenses for those that I can sell for a nominal price. Send me a PM if interested.