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 Post subject: Yellowed white plastic cases...
PostPosted: Jul Thu 10, 2008 10:57 pm 
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Some white plastic radio cases tend to "yellow" over time - which isn't too bad if it is a uniform process. I have a transistor radio with a strap. Where the strap laid on the top, the plastic is noticeably less yellowed. Are there any tricks to remove or lessen the yellowing??

Thanks....

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PostPosted: Jul Fri 11, 2008 12:27 am 
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Call me crazy, but I have had a certain amount of success using straight clorox. I just kept dabbing it on until the part went from yellowed to nearly white. Probably want to test it out on a small portion to make sure the clorox will not damage anything. Also wear old clothes :)

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 Post subject:
PostPosted: Jul Sat 12, 2008 5:02 am 
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Hi,
The bleach might work, but I think the yellowing is probably in the first thin layer of the plastic.

That would have to be wet sanded to the lighter colored plastic, then polished again. Often, that is impossible due to feature lines or molded words on the plastic.

I have had experience with telephones that have yellowed. A nice turquoise desk phone had yellowed to an awful greenish tint.
But sanding with 400 grit, then 600, and 1200 a fast polish by hand made the phone back to the original color.

I'd wet sand with the 400 just until I seen the brighter turquoise come thru, then worked with the finer grits.

This is how the Catalin guys remove the 'butterscotch' color, then they have to polish the cabinet back glossy.

Your little radio might have the yellowed color shallow or it could be pretty far down. You don't want to sand too much material off "looking' for the lighter color. It couldn't hurt to try a small area first. Trying it on a hidden area, well, the hidden area might not be yellowed because it was hidden :)
Good luck,

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 Post subject:
PostPosted: Jul Sat 12, 2008 5:18 pm 
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Gary,

I kind of figured it might require something a bit drastic.... I did try test spots with straight Clorox, Clorox 2, DiDi 7 and even Billy May's own 'OxyClean' - with absolutely NO results :( . Thanks for the tips...

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 Post subject:
PostPosted: Jul Sun 13, 2008 12:15 am 
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jgj6331 wrote:
Gary,

I kind of figured it might require something a bit drastic.... I did try test spots with straight Clorox, Clorox 2, DiDi 7 and even Billy May's own 'OxyClean' - with absolutely NO results :( . Thanks for the tips...


well time to get the spray paint out :lol: I think I heard someplace that tooth paste may get the yellow or some short of baking soda cream.

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 Post subject:
PostPosted: Jul Sun 13, 2008 6:36 am 
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Hi, I don't think paint is the answer, or at least I wouldn't.

If the cabinet is easy to wet sand, like flat surfaces, I'd try it. but if there are many feature lines, creases, nooks and crannies, raised lettering, too hard to get a uniform sand on, I'd leave it alone. Otherwise you will end up with uneven colors.

You basically have to get into the good depth where the color has not changed. That can be deep.

If the radio is left alone, the value might not drop much, just because of the change. But repainting might drop the originality value down lower.

I wonder how long it would take to mask off the part that the strap was covering, then expose it to the sun, changing the color to be uniform?

Good luck,

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 Post subject:
PostPosted: Jul Mon 14, 2008 2:35 am 
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I've tried some mild abrasives and can't tell a difference - so, it must be fairly deep. I had thought of the sun exposure idea too - but I'm not so sure UV rays are always the culprit. I have a B&D Dustbuster that has lived 99+% of it's life in a broom closet with essentially no sun exposure and it is yellowed - but relatively spared on the undersurface where it snaps into the charger. So - perhaps something in the air (we are 100% smoke free)?

I'll leave it as is before I resort to paint - this type plastic doesn't take paint well anyway.

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 Post subject:
PostPosted: Jul Mon 14, 2008 11:55 pm 
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Hi,
I have seen that also on my Dustbuster. The plastics change color on some parts. I think it is in the plastic itself. Aging or something internally. Howwever your radio was not affected where the strap was, probably UV. It might not have taken too long for the color change. Try the exposing the light area to the sun for a day and see what happens.

Take care,

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 Post subject:
PostPosted: Jul Tue 15, 2008 12:21 am 
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I've had excellent results using Westley's Bleach-White, a cleaner for whitewal tires.

This product also cleans and restores the correct color to cataln, when used jusicously.

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 Post subject:
PostPosted: Jul Wed 30, 2008 7:12 am 
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I have had good luck cleaning up white plastic with a TSP solution, two tablespoons in a gallon of hot water. It seems to work well at getting layers of dirt off, I think a lot of discoloured white plastic is made so by cigarette smoke, with few exceptions it's mostly on the surface. If that doesn't work try some Brasso.
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 Post subject:
PostPosted: Jul Wed 30, 2008 12:54 pm 
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I've submerged clock cases and small table top cases in bleach over night and had them come out white again. Great for taking out the brown in hairline cracks.


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 Post subject: Re: Yellowed white plastic cases...
PostPosted: Jan Sat 07, 2017 2:17 am 
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Knowing this is an old thread but just in case....
Has anyone tried hydrogen peroxide? I'm reading that with plastic a flame retardant was often added and with exposure to UV the retardant chemical is the yellowing culprit. I hate to paint an original but the one I'm working on has changed from beige to tones of gold except one side and the bottom which are still beige.


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 Post subject: Re: Yellowed white plastic cases...
PostPosted: Jan Sat 07, 2017 3:24 am 
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http://retr0bright.com/

http://www.amibay.com/content.php?120-summary

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 Post subject: Re: Yellowed white plastic cases...
PostPosted: Jan Mon 09, 2017 10:48 am 
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Location: Australia
Yep, I've used Retr0bright on a couple of 50's AWA mantles/tabletops with ABS cabinets - one cream, one blue-grey - that showed some pretty bad & patchy bromine yellowing.

In both cases the yellowing was completely reversed, although it took 2 or 3 treatments (I used one of the gel recipies) and you really do need to make sure it doesn't dry out in the sun or the finish will be patchy. It's been a couple of years now, and there's no sign of the yellow returning.

It's also a much more gentle treatment than you might think - on one of them I accidentally got a small dollop on the painted side of the clear acrylic dial face, and all it did was clean the dirt off the paint. YMMV though, so I'd still be wary to keep it away from sensitive areas like that...


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 Post subject: Re:
PostPosted: Jan Mon 09, 2017 1:20 pm 
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vitanola wrote:
I've had excellent results using Westley's Bleach-White, a cleaner for whitewal tires...

Me too.
You can get it about any local auto parts store in the USA.

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