Subject:
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Re: A question of humidity...
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Newsgroups:
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lugnet.color
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Date:
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Fri, 16 Jul 2004 18:20:55 GMT
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Viewed:
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786 times
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In lugnet.general, Ed McGlynn wrote:
> That's the great thing about ABS - it can be graded according to application.
> Your lawn mower cover has a different grade than your telophone handset or
> your car's dashboard. All are graded according to surface luster,
> colorfastness, etc., I'd guess.
Usually they start by grading them according to the actual plastic compound,
like acryllic (I believe that's what the old "thief-smasher" phones of the 70's
were made from) or vinyl (used as a surface layer on many dashboards). After
that they're graded according to the specific recipe (particularly with plastic
"alloys" like ABS, where the three component plastics can be mixed in different
quantities, and other additives can be introduced to achieve different
characteristics), and they spec them according to qualities (luster isn't really
one of them, since post-production oxydation will often cause the surface to
look more glossy), mostly dealing with stuff like impact rating, tensile
strength, UV resistance, glass-transition point, melting point (only for
crystalline materials), and how it's affected by temperature extremes.
> Since the reaction to humidity by the blue baseplates, and the baseplate
> grade as a whole, we can assume that that grade is different. I'd guess its
> grade has the colorfastness quality that LEGO's looking for (or looked
> for in the case of blue).
Not really. When you run plastic in different colors for the same application,
you usually just use the same raw resin for each color, so the only real
chemical difference would be the coloring agents. And while they can cause
slightly different behaviors in the plastic, I'm not sure it'll affect how the
plastic reacts to humidity (well, unless you do something stupid like using
sodium as a coloring agent, potentially causing it to explode if you get it
wet).
> Maybe there's an impact on the ABS's coefficient of expansion for that grade
> and humidity level.
I'm pretty sure that the baseplates aren't even made from ABS. I've spent about
six years working almost exclusively with ABS, and it just seems like it's made
from some other type of plastic.
> By the way, I noticed a little while back that BASF is consolidating it's ABS
> production facilities in Europe, so I wonder if that'll effect coloration and
> availability for LEGO, if they use BASF as a supplier.
Eh, as long as it's going to continue to be produced in Europe, the only affect
it should be able to have is by adjusting the cost due to transportation.
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Message has 1 Reply:
 | | Re: A question of humidity...
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| SNIP (...) Please explain this to me.....sodium will explode when it gets wet? If this is true than wouldn't the oceans blow up? Just curious.... Jen (20 years ago, 17-Jul-04, to lugnet.color)
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