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 20:47:49 GMT
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Viewed:
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2535 times
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On Wed, 30 May 2001, Cary Clark (<GE5u0s.MLF@lugnet.com>) wrote at
18:00:14
>
> My theory is that the ABS is reacting with some (unknown) airborne
> chemical, and the presence of UV radiation speeds the reaction. That
> chemical concentrates in wooden boxes, but I'm no chemist.
>
> It would appear to be prudent to store white bricks in airtight plastic
> bags. Maybe ABS outgassing protects itself from the yellowing process.
> It would be really fascinating to hear about anyone's experience with
> yellowed bricks in old MISB sets. Has anyone found a yellowed brick in a
> perforated polybag?
It is distinctly possible that there is more than one cause of
yellowing, as there appears to be more than type of yellowing.
Having said that, the following suggestion covers both removable
(surface) and non-removable yellowing, depending upon the age & exposure
of the bricks.
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 :-)
--
Tony Priestman
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Message has 2 Replies:
 | | 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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Message is in Reply To:
| | why parts yellow (was Re: Sopwith Camel pictures)
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| Frank Filz showed me a brick out of a sealed set from the 70's that had yellowed in the box, once opened over twenty years later. The box may have been near or in a store window, so it may have gotten UV through the box, but the parts in the same (...) (23 years ago, 30-May-01, to lugnet.general)
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