Subject:
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Re: S@H exclusive minifigure has been shipped! (#3723)
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Newsgroups:
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lugnet.general, lugnet.lego.direct
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Date:
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Sat, 21 Oct 2000 21:05:09 GMT
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Viewed:
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11 times
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In lugnet.general, Christopher Lindsey writes:
> Why not? Copper was used architecturally much earlier than that late 19th
> century. I'm sure *someone* noticed that the stuff turned green over time.
> :)
Thanks for retrieving those details from the mint!
If you want to see bronze in green, blue, black, brown, even blue, red and other
wacky colors, take a look at some ancient coins. Surf ebay -- they have a
burgeoning ancient coin section that gets wonderful photos.
Bronze is an alloy of copper and tin. Copper and zinc alloy (orichalcum) was
occasionally substituted in antiquity because it was cheaper, much like today.
You never knew precisely what was in an ore, and the impurities give a lot of
character to ancient metal. One curiosity: ancient silver doesn't tarnish! It's
not pure enough.
Patina, the color coating, is formed by chemical reactions between the metals,
their impurities, and the nearby dirt and air, so there are identifiable primary
reaction colors on one hand, and chance mixture on the other. Copper oxide
contributes that green color but other ingredients enter in. It does take
centuries to build up a stunning texture. Accelerated antiquing has been done by
burying bronze in shit (that valuable industrial commodity.)
I'm not sure if my leg is being pulled, but one coin dealer was telling me that
ear wax helps fortify and feed a good brown patina.
A really beautiful patina of whatever color can result from a lucky combination
of centuries of quiet burial and centuries of safe keeping. I don't understand
why it was necessary to clean the patina off Liberty.
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