Gary Coffman wrote:

On Fri, 02 Jul 2004 13:37:36 GMT, Seppo Renfors wrote:
Tom McDonald wrote:
Seppo Renfors wrote:
Gary Coffman wrote:
On Tue, 29 Jun 2004 05:48:01 GMT, Seppo Renfors wrote:
Gary Coffman wrote:
[..]

Again, porosity is the problem, and that should show up on
radiographs, as it does for R666 (which certainly shows evidence
of being melted in atmosphere, though not necessarily evidence
of being cast), but none of the other artifacts presented show
that sort of porosity.

See:
http://www.iwaynet.net/~wdc/copper.htm

The 4th and 5th pictures down.

Those pictures do not show any evidence of the characteristic
porosity copper casting would produce.


They disagree with you as it states "The casting bubble can clearly
been seen...."


Gary showed that the porosity typical of pure cast copper is
not present in that artifact. He even explained in just below.

Please point out the "porosity" in this sample:

Two copper pigs:
http://people.uncw.edu/simmonss/P6030052.JPG

The evidence of porosity is available to the naked eye
in that thin copper flake. There are dozens of tiny bubbles
in evidence, You don't even need a radiograph to see
them. A radiograph or a density test would settle the
matter absolutely, but neither is really needed here as
the sizes and numbers of bubbles already visible are
clear indications of atmospheric melting.

I don't actually SEE any bubbles at all in the pigs, not even when
magnified to its largest extent - where 1 cm = 3.5 cm on screen.

The casting is obvious in this:
http://people.uncw.edu/simmonss/LA_1240-1.4.jpg

The large numbers of tiny pits in that piece are suggestive
of porosity, but a stereo radiograph, or a density measurement,
would be required to determine if the piece is actually riddled
with porosity, or if we're just seeing corrosion pitting of otherwise
sound copper (if the object is indeed copper, and not a bronze
alloy).

Now in this item I can definitely see "holes" that you call "porosity"
- and you have difficulty accepting it as cast - despite it clearly
displaying the shape a mould. I would even suggest that this metal was
well overheated when it was cast from the pure look of it.

Both pictures show melted copper - pre Colombian melted copper! It
leaves Gary's statements hanging in the air.

Pre-Columbian, or Spanish Conquest? I don't see a precise
dating associated with the individual objects. The web site says
the collection of objects date from the Post Classic and Spanish
colonial periods. Also, the web site says the objects are a mix
of copper, copper-tin bronze, and copper-arsenic bronze. What
evidence do you have that the two particular objects you selected
from that collection are pure copper rather than bronze?

The items are pre-Columbian from around 1300 AD. They are described as
"Two copper pigs". I accept their view of it being copper.

However if one considers that "bubbling" has been claimed to be caused
by "overheating" in a annealing process - then it is saying "melted"
at the same time, as it cannot bubble UNLESS a portion of it is
melted. Also "welding" requires the melting of the metal - or so
goddamned close to it that the friction heat generated by a blow on it
does melt the metal.

You're wrong on both counts. Copper is a malleable, ie plastic, material
even at room temperature.

It is malleable in relation to granite but then so is steel....

At annealing temperature (500F or greater)
it is much more so.

Fahrenheit is a long ago discarded temperature measure here and it is
fairly meaningless to me - however the 500F appears to be a
temperature people use to bake cakes or roast a leg of lamb in a
standard domestic oven. I don't even see the copper glowing red from
heat at that point. Naturally annealing can be done at almost any
temperature, but from other things I have read, much much higher
temperatures are in fact used before the term "annealing" is applied
to it. Eg go get the metal red hot.

But one thing that does puzzle me in this claim of yours. A piece of
pure copper, as a result of bringing it up to baking temperature can
cause "bubbles" - forget the baking, take it to dark red state to form
"bubbles". From what does the "bubble" form, we are talking about pure
copper here? How did (whatever) get INTO the copper to form a bubble
in the first place?

Bubble gum need not be molten for bubbles to be
formed in it, neither does copper.

Totally irrelevant. But you do point to an external source for the
bubbles by that example - so how does it actually get INTO the copper
in the first place if it isn't (partially) melted?

And while copper can be welded, in
an inert atmosphere, by melting, it can also be welded at lower temperature
by pressure.

No it can't. "Pressure" in itself does almost nothing. A loaded
freight train running over a "copper" coin only flattens it and does
nothing else. It is the sudden impact pressure that causes the
molecules to move rapidly, that causes FRICTION, which in turn causes
heat and if sufficient sudden pressure is applied (eg hammer blow to
already hot metal) it CAN melt the material. To "weld" something by
definition requires bringing part of it to a liquid state - ie melted
in the portion being welded.

WELD - verb [with obj.], join together (metal pieces or parts) by
heating the surfaces to the point of melting with a blowpipe, electric
arc, or other means, and uniting them by pressing, hammering, etc -
OED.

Though I note that "metals" isn't the only things welded - plastic is
also welded, but the rest applies just the same. It also reminds me of
an axle being welded onto the wheel mounting flange. The axle is
placed against the flange with pressure, and spun very fast. When
suitably hot, the rotation was stopped, added pressure was applied,
the axle was pushed in on the flange by about 1 cm, this to weld it.
This melted the material in the joint part as well as expanded the
contact area.

Those are two logical examples of melting occurring - the knowledge of
melting copper existed. It beggars belief that scraps and off cuts
were NOT melted when the process must have been known to them. That
people suggest they would rather go and do hard manual labour another
day to find a piece "just right" for the job, when it is right there,
right now, right before them. All they have to do is melt it into one
lump.

And wind up with a porous lump of no use to anyone. Really, you haven't
absorbed anything anyone has been telling you about the atmospheric
casting of pure copper.

The evidence exists that casting was used - Eric Stevens has provided
expert testament to that effect. I have pointed to actual evidence
(such as exists) including in this post. You label cast copper as "of
no use to anyone" when it obviously was of use. You are probably very
right in everything you say -for today's use when high quality melted
copper can he had - but that isn't the issue at all. Frankly, if you
find it "useless" in your endeavours is irrelevant, it doesn't mean
the ancients did. YOU are not them.

The implied suggestion they would rather do the hard labour, and not
proceed with the easier option available immediately to them, isn't
consistent with known human behaviour.

That's your interpretation. But since your interpretation is wrong, your
conclusion is also wrong.

You are very quick at labelling "wrong" without a single shred of
proof or alternate theory! I therefor totally reject such
unsubstantiated claims as worthless.

--
SIR - Philosopher unauthorised
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The one who is educated from the wrong books is not educated, he is
misled.
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