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vc aa copper blue green

updated tue 30 sep 97


Grimmer on tue 2 sep 97

I dunno. I get the dull green a lot, and the black, too. What
with all the calcia and low silica, this glaze is rather unstable.
That's one of the things I like about it. Thickness seems to have
a lot to do with it. Too thick and it crystalizes out to that
metallic black.
Ron Roy correctly pointed out on the list that this shouldn't be
considered a functional (foodsafe) glaze, due to its flux
imbalance (way too much calcia) and lack of succicient silica.
It definitely crazes on my porcelain (and probably most other
clays), and probably is easily attacked by acidic foods. I
should have considered that before I posted the recipie to the
Question: does a foodsafe, matte, alkaline blue/green exist?
That said, it does remain one of my faves for vases and such.

steve grimmer
marion illinois
In a personal note, Cynthia Blau wrote:
> I've been using the same glaze for 2 years with great success. But this
> week some pieces came out dull green/black/greyish. They were in
> different places in the kiln. Some pieces did come out beautifully. Do
> you have any idea what could have happened?
> Cynthia Blau
> Fairfax, VA