Leon Popik on thu 13 feb 97
I figured someone could answer this from clayart. I figure the glaze is
oxidizing, what do you think?
----------
> From: msl@the-spa.com
> Newsgroups: rec.crafts.pottery
> Subject: Soda Glaze Fading??
> Date: February 10, 1997 9:54 PM
>
> I soda fired some stuff in a glaze called Rob's Green this summer at
> Haystack. It seems like the glaze has changed color since the firing
> from darker green to light aqua blue-green. Is this possible? If so,
> why is it happening. The glaze ingredients are barium carb, gerstley
> borate, whiting, cornwall stone, copper carb and bentonite.
>
> Mark
>
>
Michael kline on fri 14 feb 97
Surely the glaze has not changed just sitting on the shelf? I
assume you have tried firing this glaze in a different kiln since haystack.
My experience with copper in a soda kiln is that it tends to be fugitive,
especially near inlets of your spray turning form dark to light.Essentially
you are increasing the glazes alkalinity. I have not used Rob's green but
use a similiar cooper glaze simply because it reacts so well in a soda
kiln. Another factor is clay color. If you are using porcelain you will get
a much lighter green, stonewear will produce a darker hue of green.
hope this is helpful.
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Carol Ratliff.clayart.CLAYART.MAILING LIST on fri 14 feb 97
In a message dated 97-02-13 07:01:33 EST, you write:
<< ----------------------------Original message----------------------------
I figured someone could answer this from clayart. I figure the glaze is
oxidizing, what do you think?
>
> I soda fired some stuff in a glaze called Rob's Green this summer at
> Haystack. It seems like the glaze has changed color since the firing
> from darker green to light aqua blue-green. Is this possible? If so,
> why is it happening. The glaze ingredients are barium carb, gerstley
> borate, whiting, cornwall stone, copper carb and bentonite.
>
> Mark
>>
It sounds like it to me too. What combination or lack of materials in a
glaze would allow this? With soda firing it sounds even stranger. I know it
happens in raku, but .....soda?
So instead of asking what went wrong maybe I should be asking what are the
requirements to make any glaze stable - especially with copper?
Carol ....In San Diego
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