Subject:
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Re: why parts yellow (was Re: Sopwith Camel pictures)
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Newsgroups:
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lugnet.general
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Date:
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Wed, 30 May 2001 22:00:38 GMT
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Viewed:
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2634 times
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On Wed, 30 May 2001, Dave Schuler (<GE62DC.J0D@lugnet.com>) wrote at
21:00:48
> In lugnet.general, Tony Priestman writes:
>
> > A prime suspect must be decomposition by free radical attack. Exposure
> > to light will accelerate this, and putting the bricks in the dark
> > afterwards will not slow it down again, if there is nothing in the
> > plastic to scavenge the radicals & stop the reactions. The different
> > amount of yellowing in different coloured bricks can be explained if
> > dyes of different colours have different levels of effectiveness as free
> > radical traps. It could also just be some of the dyes mask the yellowing
> > better :-)
>
> I don't know nuthin bout no free radicals, but my grandfather has had
> white vinyl siding on his house for about fifteen years, and its still a lot
> whiter than my white LEGO bricks purchased at about the same time (and which
> have spent a lot less time in the direct sun than his house). I know the
> material itself is different (though it would be cool to have a house with
> LEGO siding), but isn't there some way to marry the benefits of the two
> plastics? 8^)
uPVC for outdoor use in windows, etc. is absolutely brimming with the
stuff that stops it going yellow & decomposing. Because LEGO isn't
designed for outdoor use, it probably isn't :-)
(cf. 5 year model replacement cycle at Legoland)
Dunno much more myself, I've just got a friend who's a chemist.
--
Tony Priestman
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Message is in Reply To:
 | | Re: why parts yellow (was Re: Sopwith Camel pictures)
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| (...) I don't know nuthin bout no free radicals, but my grandfather has had white vinyl siding on his house for about fifteen years, and its still a lot whiter than my white LEGO bricks purchased at about the same time (and which have spent a lot (...) (23 years ago, 30-May-01, to lugnet.general)
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