most yellowing is due to UV radiation over time (and not cigarette tar or other grime as sometimes believed). It is a photochemical change that has altered the molecular structure of the plastic all the way through. You can't just clean it off, nor is there a way to reverse the process.

Place your piece in a Clear container and fill with Peroxide to cover item then cover seal with seran wrap and leave in the Sunlight or a UV lamp for a few days and thats it.

That is what was posted in the thread about it. I copied and pasted it into my notes on my phone. I tried it on some clear bride of pinbot plastics and it did not work. Maybe it will work better for you

Yea there was a thread about this issue . I think the guy said he went to a beauty supply store to get the peroxide because it's stronger . I haven't tried it yet but I am curious .

I read somewhere that the Commodore Amiga guys are finding this is not a permanent solution.. just a FYI, i thnk they are re-yellowing even without UV exposure..

That's what I've always been told. And I've tried everything there is to get rid of it on some old plastic, and nothing works.

It's called Retro-Brite.

Tried with my Diner coffee cup and it did not work for this type of plastic.

I Use the Salon grade Peroxide as it is the strongest formula that you can get along with a UV lamp. Works fine for me. I also use it for aged decals.

Biggity Bam!

https://pinside.com/pinball/forum/topic/say-goodbye-to-old-yellowed-plastics

Excellent! This is what I love about this site.