Subject:
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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 18:00:14 GMT
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Viewed:
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3173 times
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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 box that were inside a plastic bag
had not yellowed.
Show what do we know?
- ABS yellows. White, light grey and blue bricks show the yellowing most
visibly.
- Parts yellow with age, but not uniformly. Bricks faces against other
faces do not yellow.
- Sometimes the yellowing can be bleached out, but as Tom Stangl avows,
sometimes no amount of bleach can take the yellowing out.
- Parts do not uniformly yellow, even though all sides are exposed to
air. I have monorail track that is partially yellowed, but was
presumably completely air exposed.
- Parts that get sun exposure yellow faster. This is common lore; can
anyone dispute it?
- Parts in sealed boxes or in wooden drawers can yellow, apparently
faster than parts that get diffuse sunlight.
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?
Cary
"Fredrik Glöckner" <fredrik.glockner@bio.uio.no> wrote in message
news:m3itij7ufq.fsf@crossblock.localdomain...
tnt@arnesson.nu (Tobbe Arnesson) writes:
> I have pre dark ages bricks that used to be white too. But they have
> been stored in light secure boxes and such so I have no clue how that
> occured, I suppose it's aging in the plastic.
On the subject of my 5580 Highway Rig which was on display, I clearly
noted that only the visible white parts had yellowed. The parts of the
plates that were covered with other parts, for example, were not
yellowed. This leads me into believing that it's the light that yellows
the parts.
Could it be that your white parts were already yellowed before you put
them into the light secure boxes? Perhaps you did not notice/care about
this effect at the time?
Or it could be that the light exposure to the parts had started a
photographic process which continued during the storage period? This
is, BTW, how photographic paper work. The exposure takes place, and
then the paper is put into a catalyst liquid (aka developer liquid),
which turns the exposed parts black. The paper doesn't actually turn
black during the exposure.
Fredrik
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Message has 2 Replies:
 | | Re: why parts yellow (was Re: Sopwith Camel pictures)
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| On Wed, 30 May 2001, Cary Clark (<GE5u0s.MLF@lugnet.com>) wrote at 18:00:14 (...) 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 (...) (23 years ago, 30-May-01, to lugnet.general)
| | | Re: why parts yellow (was Re: Sopwith Camel pictures)
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| (...) According to our resident plastics expert at work, both ABS and CA (cellulose acetate) polymers will discolour from exposure to ultra-violet light. The UV energy directly "attacks" the molecular bonds of the polymers. And presumably this (...) (23 years ago, 30-May-01, to lugnet.general)
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Message is in Reply To:
| | Re: Sopwith Camel pictures
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| (...) On the subject of my 5580 Highway Rig which was on display, I clearly noted that only the visible white parts had yellowed. The parts of the plates that were covered with other parts, for example, were not yellowed. This leads me into (...) (23 years ago, 29-May-01, to lugnet.general)
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