Whitening Yellowed Plastic (Sweet!)

**Gubi** · #1 (**permalink**) 03-03-2009, 10:59 PM

This is pretty cool: a bunch of guys have figured out a way to re-whiten yellowed ABS plastic using peroxide. They've released the instructions and formula for the gel. Looks like it works great!

I'm pretty amazed - I'd always assumed such yellowing was irreversible. Somebody should test this on a set of yellowed taillight lenses (I believe they're ABS) to see if it works for that use case.

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Alex · #2 (**permalink**) 03-04-2009, 02:05 AM

Very interesting indeed, providing that the peroxide doesn't embrittle the plastic. No mention of that is made on the site. Might give it a whirl, though ....

**Gubi** · #3 (**permalink**) 03-04-2009, 09:27 AM

Actually, if you look at the chemistry pages they explain how it works, and unlike chlorine bleach it should not cause weakening of the plastic.

**steveh29** · #4 (**permalink**) 03-04-2009, 11:38 AM

Very cool (and useful). I found it comical that the advertisement at the top of this thread was for tooth whitening!

Little Italian · #5 (**permalink**) 03-12-2009, 01:43 PM

I wonder if this would "bleach a set of yellowed headlight bubbles clear again?

**Gubi** · #6 (**permalink**) 03-12-2009, 01:55 PM

I'm curious as well. On clear plastic, it's not obvious to me how deep the yellowing penetrates the plastic, or how deep this method will bleach the plastic Still, if they're already shot it can't hurt...

**Farace** · #7 (**permalink**) 04-13-2009, 10:31 PM

What type of plastic are our coolant overflow bottles and brake fluid reservoirs made from?

**garwood1** · #8 (**permalink**) 04-18-2009, 02:49 AM

Headlight covers often respond well to a dose of Blue Magic metal polish (don't laugh) lightly applied, followed by AG SuperResin Polish. Also works a treat on modern polycarbonate headlamps, as well (toyota's, etc.) - they go from milky and almost opaque to clear. Did this every few years on my Subaru Legacy in California, where ALL exterior plastics quickly turn to cr*p...made such a difference driving at night !

As to coolant overflow bottles and brake reservoirs, they are most likely polypropylene.

**101 Alfa Mike** · #9 (**permalink**) 04-27-2009, 04:26 PM

Yes. I have polished the headlight covers on my Nissan Maxima with good results.

bianchi1 · #10 (**permalink**) 05-01-2009, 07:36 PM

i wonder how this would work on soft tops plastic windows?

jbracefan1977 · #11 (**permalink**) 05-24-2009, 04:25 AM

nice... and it does not damage the plastic... will try this one out. thanks