In message , Bob Masta
writes
On Wed, 5 Mar 2008 14:55:54 +0000, Susie Thompson
wrote:

In message , Bob Masta
writes
On Tue, 4 Mar 2008 22:20:30 -0600, "The Splanns"
wrote:

Hi everyone!
I've been reading the post for some time and I have a question too. Has =
anyone ever made anything with copper inlay? How exactly would copper =
act in cone 6 glaze firing? I would greatly appreciate your advice or =
even a reference to where I can find more information on a subject.
Thanks,
Veronika

Copper won't survive at cone 6. It melts at 1984F (1084C), which is
roughly cone 03, but it oxidizes like crazy long before that. If you
were making flat tiles, you *might* be able to get it up to melting by
covering it with a protective flux, but I imagine this would take some
amount of experimentation to get working.

This seems to be generally true of all common metals in oxidizing
atmospheres... they oxidize long before they get to melting.
I don't know if you could get decent melting in a fuel kiln fired in
reduction, but I bet it wouldn't be easy... you'd have to keep it in
reduction throughout the whole firing cycle.

Best regards,


Bob Masta

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This is a question I've often wondered about for many years and never
got around to asking. Glad it's turned up now. Given that the copper
oxidises long before melting, would it leave sufficient traces of oxide
at lower earthenware temperatures when it could, maybe, be used as glaze
colourant as part of design. Would it always produce copper oxide, or
would that depend on kiln atmosphere? Can any other metals be used in
this sort of way? Hope you can follow my thinking - I have a bad cold
and a fuddled brain. Thanks


I only have personal experience with oxidizing (electric) kilns.
I think you could probably get this to work, and it might make
an interesting effect, at least for non-functional ware. The copper
or iron (steel) that I've fired invariably oxidize to black, but I
haven't put them next to a glaze. I'd expect the oxides to bleed
into the glaze at the edges of the original metal, perhaps
giving a green halo around the black copper oxide lump.
Might be fun to experiment with different base glazes to see
which promotes the most bleeding.

If you covered the metal with the glaze application, it should
reduce the oxidation when the glaze becomes fluid enough
to block oxygen from getting to the metal. So there may be
some interesting effects with different thicknesses, as well
as different glaze melting temperatures. Try flat tiles at
first, so you can over-fire the glaze and not worry about
it running off the piece.

And please report back with your results!

Hi Bob

I don't make anything useful at all, so no problem there. I'm not
working at the moment but will give this a go when I get going again.
There may also be some ironstone clay which I can dig out of the ground
on a friend's farm, so that's going to be something to play around with.
What might the firing range of ironstone be?

Thanks for your thoughts.

Susie, Isle of Arran, Scotland
--
Susie Thompson
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