Kathy McDonald on sat 16 dec 06
comment
On Dec 15,2006 Connie Christensen wrote:
Thanks Tony, now I don't think I'm quite so crazy. In the
last couple
of years I've tested hundreds of glazes - testing, altering,
retesting, more altering, overlapping, and on and on. I
thought I had
one that worked - a turquoise glaze, but it needed a liner
glaze
because it wasn't food safe and seemed to be putting to much
copper
in the kiln and messing up the shinos.
Connie,
I am interested in the comment you made about copper messing
up shino
when there is too much of it in the kiln. Normally the shino
glaze I use (Malcolm's
Shino) is a gorgeous orangey color when it's fired on the
clay I use which is
Tucker's 1080.
I find when the kiln has copper reds in the same load it
totally changes and goes
all funky, not unpleasant, but sort of like a calico cat
color. There are some examples
here. Sorry they are scattered throughout the images posted.
http://s4.photobucket.com/albums/y130/claylady/?start=40
I have since fired the same shino in a load without the
copper red and it is much
more like the shino I expect. I fire to cone 10 with
natural gas.
I was wondering if the glaze guru's in the group might have
some insight into what
makes this happens.
If needed I can post the recopies for the glazes and
additional firing details.
Thanks,
Kathy
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Bonnie Staffel on sun 17 dec 06
You have just experienced what copper does. It is a well known fact that
copper vaporizes in the kiln and migrates. Even in my electric kiln, an
adjacent pot will show the effects of this activity by copper. It might
even follow that the copper fumes might even get into the studio if proper
venting is not in place. Lead does the same thing. Chrome is in that
league as well.
Bonnie Staffel
http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
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