yellowed plastic

[bholio]

I just got a Marui Big Bear from a friend. The hard plastic body has yellowed over time. Same with the Super Champ rims he gave me, but I need to look closer to insure it's not paint.

What causes this? The body is not yellow under the decals. Even the plastic under *clear* parts of decals is not yellow. The underside is not yellow.

How do I get rid of this? Do I need to get rid of this before I paint it?

[snollan]

Sounds like the decals block the UV from the sun. <--My Guess

2nd Guess the plastic continues to cure over time, like fiberglass.

I don't think you can get rid of it. Maybe you can dump the rims in some bleech. I would just paint the rims and then put a ton of clear coat over them.

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I am so smart, I am so smart! S-M-R-T..I mean S-M-A-R-T!!

[DJTheo]

The yellowing is more on the surface, so you can partially polish it off...

http://www.vintagetamiyarc.com/

[WillyChang]

The yellowing of plastic is pretty normal with age... Wild Willy wheels are especially bad at this, turning a light brown. Like Theo says, yes - its usually on the surface only.

Exposure to sunlight imho is the usual culprit, although these days UV from flourescents and lowvoltage halogens is pretty intense too. Contact with oils also seems to speed the yellowing up.

The yellowed plastic does not change in properties, so its perfectly paintable as is (after usual paint prep). Sanding the yellow off is probably too much work.

Using a coat of primer is ideal, otherwise just make sure if you're painting with light colours to check the paint's opacity. Eg Tamiya's TS Pearl White is pretty translucent and does a lousy job of covering-up; use TS Pure White to coat the plastic first.

[DJTheo]

Why would he want a pearl effect (a bit redish) on his Super Champ wheels???

Better use Tamiya primer first, covers the best and is nice white semi matt, may possibly not even want to paint it afterwards...

http://www.vintagetamiyarc.com/

Edited by - DJTheo on 23 Oct 2002 08:49:09

[WillyChang]

quote:

Why would he want a pearl effect (a bit redish) on his Super Champ wheels???

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Same question why too - on some Willy wheels...!!

Actually they came out pretty good; I used white then pearl white on top. It has a colourless shimmer on the top, not quite noticeable.

Either way a lot better than the browned stained plastic.