Kurt Unterschuetz on tue 15 oct 96
One of my glazes uses Strontium Carbonate and Copper Carbonate. I buy my
glaze ingredients from Great Lakes Clay Co in Carpentersville, Illinois.
The last time I purchased these ingredients, they had changed. The Copper
Carb was of a lighter color than before. The old stontium carb I used
read Solvay on the bag and was hydrated to keep the dust down. Now it's a
different bag and is fine, like silica. Great Lakes said someone bought out
the copper carb business and now this lighter colored stuff is all you can
get. They also said the strontium carb was different because a different
vain was being mined, or something like that. I don't really remember the
reason about the strontium carb changes.
Needless to say my beautiful oriental green glaze no longer turns out at
cone 6. So I will have to do some testing to see if I should use more or
less of the above mentioned ingredients. My old ingredients must be
available somewhere! Can anyone help suggest how I go about confirming that
things have changed or how I can locate my old trusty glaze ingredients.
TIA
Kurt Unterschuetz
SchatziBoyz Pottery
Marengo, IL
http://www.mc.net/schatzi
Bruce Johnson on wed 16 oct 96
>----------------------------Original
message----------------------------
>One of my glazes uses Strontium Carbonate and Copper Carbonate. I buy my
>glaze ingredients from Great Lakes Clay Co in Carpentersville, Illinois.
>
>The last time I purchased these ingredients, they had changed. The Copper
>Carb was of a lighter color than before. The old stontium carb I used
>read Solvay on the bag and was hydrated to keep the dust down. Now it's a
>different bag and is fine, like silica. Great Lakes said someone bought out
>the copper carb business and now this lighter colored stuff is all you can
>get. They also said the strontium carb was different because a different
>vain was being mined, or something like that. I don't really remember the
>reason about the strontium carb changes.
>
>Needless to say my beautiful oriental green glaze no longer turns out at
>cone 6. So I will have to do some testing to see if I should use more or
>less of the above mentioned ingredients. My old ingredients must be
>available somewhere! Can anyone help suggest how I go about confirming that
>things have changed or how I can locate my old trusty glaze ingredients.
>
>TIA
>Kurt Unterschuetz
>SchatziBoyz Pottery
>Marengo, IL
>http://www.mc.net/schatzi
>
>Hi Kurt, Yes indeed the copper mine has once again changed handsand seems
that the lite green is here in our area for now.Copper Carb is a processed
thing and changes alot I buy it by the fifty pound bag which last about a
year in my production world., so it is a pain when it chages . In the
eightys it was dense copper that all the raku folks loved now they don't
mine that anymore.[does anyone have some laying around]. Maybe you could
call some other suppliers and see if they have some of the darker green
around and buy you a stash of it. call the owner of U.S. pigment 1 800 472
9500 He's the copper carb king pin in our area and sounds like he has some
ideas to make it work. Don't know anything about that other stuff my world
is copper and frit. Bruce Madtown Wis.
"POTTERS IGNITE"
LINDA BLOSSOM on wed 16 oct 96
I have talked with Sayeed at US Pigment extensively about the copper
carbonate. He tells me that there were only two manufacturers of copper
carbonate in the US. Baldini, who made the darker green, and Griffith who
made the light green. Griffith bought out Baldini. If you weigh a given
volume of each, you will find a difference. The lighter green is hydrated
and contains less copper. You can calcine it to reduce the water.
However, the problem is more than just increasing the amount you useto make
up for getting more water and less copper. I found that the green
volitized out and was pale and splotchy. Griffith has improved the
process, now making carbonate that looks like the original Baldini. You
can return the light green and call Sayeed for some of the darker green.
In all but one glaze, it is working fine for me. I am going to try that
glaze with copper oxide. In fact, I am considering switching to oxide. I
seem to remember posts recently on conversion. I guess it is hard, given
the unpredicatable amounts of water and copper. This is not atmospheric
water however, it is molecular. Anyone have a rough estimate on a
conversion? I know this nightmare only too well!
Linda Blossom
2366 Slaterville Rd.
Ithaca, NY 14850
blossom@lightlink.com
http://www.artscape.com
607-539-7912
LINDA BLOSSOM on wed 16 oct 96
Forgot to ask, do we have anyone in England that has a local source for
copper carbonate? I was speaking with Peter King once and he told me about
some that he used while he was in Costa Rica that came from England. He
said it was emerald colored unlike anything he had seen.
Linda Blossom
2366 Slaterville Rd.
Ithaca, NY 14850
blossom@lightlink.com
http://www.artscape.com
607-539-7912
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