Re: Copper Casting In America (Trevelyan)
From: Tom McDonald (tmcdonald2672_at_charter.net)
Date: 06/30/04
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Date: Wed, 30 Jun 2004 16:22:51 -0500
Yuri Kuchinsky wrote:
> Tom McDonald wrote:
>
>>Yuri Kuchinsky wrote:
>>
>>
>>>Gary Coffman wrote:
>>>
>>>
>>>>On Mon, 28 Jun 2004 09:04:49 +1200, Eric Stevens <eric.stevens@sum.co.nz> wrote:
>>>>
>>>>
>>>>>On Sun, 27 Jun 2004 03:03:50 -0400, Gary Coffman <ke4zv@bellsouth.net>
>>>>>wrote:
>>>>>
>>>>>
>>>>>>On Wed, 23 Jun 2004 23:46:01 -0500, Tom McDonald <tmcdonald2672@charter.net> wrote:
>>>>>>
>>>>>>
>>>>>>>Eric Stevens wrote:
>>>>>>>
>>>>>>>
>>>>>>>>On Fri, 11 Jun 2004 22:57:04 GMT, ke4zv@bellsouth.net (Gary Coffman)
>>>>>>>>wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>>But that said, casting pure copper is a bitch.
>>>>>>>>
>>>>>>>>
>>>>>>>>This from the guy who has just written that the task can be undertaken
>>>>>>>>by low-skilled workers?
>>>>>>>
>>>>>>> Eric, I read that to mean that casting, in general (as with
>>>>>>>iron, silver, bronze, gold, etc.) can be done by folks with
>>>>>>>fewer skills than smiths. However, copper appears to present
>>>>>>>particular problems with casting that are not so pronounced with
>>>>>>>other metals, and which require higher skill levels than would
>>>>>>>be required by those who cast other metals.
>>>>>>
>>>>>>Exactly, and further, skill alone isn't sufficient to make sound
>>>>>>castings of pure copper. The proper equipment is also required.
>>>>>>Specifically, an inert atmosphere furnace. That technology
>>>>>>didn't exist until the late 19th century.
>>>>>
>>>>>Just as well the ancient egyptians didn't know that they couldn't do
>>>>>what they were doing. :-)
>>>>
>>>>So, are you claiming to have evidence that the ancient Egyptians
>>>>successfully cast pure native copper?
>>>>
>>>>The metallurgical references I have say that native copper was
>>>>extremely rare in Egypt. Almost all of the copper they had was
>>>>refined from ores (smelted), and the results were *not* pure
>>>>copper. Rather, they were alloys, whether intentional or not,
>>>>of copper, arsenic, zinc, iron, or tin. These alloys behave *very*
>>>>differently from pure native copper when casting is attempted.
>>>>
>>>>Gary
>>>
>>>
>>>Well, Gary, the folowing sure seems to imply that the
>>>ancient Egyptian did some copper casting.
>>>
>>>[quote]
>>>
>>>Ancient Egyptian raw materials: metals - copper, bronze,
>>>iron, gold, silver, lead
>>> http://nefertiti.iwebland.com/trades/metals.htm
>>>
>>>
>>>Re: copper objects [rather than bronze]:
>>>
>>>The objects were generally cast, which is quite difficult to
>>>do with copper because of the formation of gas bubbles
>>>during the pouring of the metal and its shrinking when it
>>>cooled down. Then they were hammered cold to give them their
>>>final form.
>>>
>>>[unquote]
>>
>>Yuri,
>>
>> Your site tells us that copper ore was what was available, not
>>native copper; and that it had to be smelted before use. IOW,
>>it's not clear whether the Egyptians ever had copper of the
>>purity of the native copper in the upper Great Lakes area. In
>>addition, the smelting and melting of that copper would more
>>than likely have resulted in a copper alloy, not pure copper.
>>
>> Of course, if you have better evidence that shows Egyptians
>>cast 99+% pure copper, you are welcome to present it here. I
>>for one would be very interested in that evidence.
>>
>>Tom McDonald
>
>
> My main point here is that Gary Coffman is wrong with his
> speculations that copper casting was too difficult for
> ancient peoples to do.
>
> I'm merely trying to teach Mr. Coffman a few things about
> metalworking, as it applies to ancient peoples.
Yuri,
I've been boggled by things you've written before, but this
takes the cake. *You* teaching *Gary* anything about
metalworking by the ancients. Priceless!
Gary hasn't written that casting was too difficult for ancient
peoples to do. Clearly, they did. But in the case of copper in
the upper Great Lakes area, copper casting was totally
unnecessary. Also, with any even remotely likely technology
available to the Indians here, the resulting pure copper casts
would be very inferior to the same artifacts made by smithing.
You are trying to tell us that Indians in the Great Lakes
Archaic period cast pure copper with techniques that not only
perfectly mimicked smith work, but also of such quality that
even today it is hard to do so well. You also want us to
believe that this technology left no trace other than the
artifacts. You finally want to tell us that the Indians,
obviously very savvy folks, developed this technology that looks
precisely like smithing for no reason whatsoever.
As Gary and Paul have pointed out, the intelligent thing for
folks to do with the kind and quality of copper available to
them would be to hammer it, using cold hammering and annealing.
If you have evidence of archaeological sites in the upper Great
Lakes that show evidence of the technology required (re-read
Gary and Paul's posts, and follow the links to the Neubauer
Process for what to look for), present it.
Teaching Gary about metalwork :-). Priceless, just priceless.
Tom McDonald
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