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oxide toxicity

updated sat 31 aug 96


Hatton on sat 3 aug 96

I just cut the amount of copper carb in my favorite glaze in half
without changing it much (7.5% vs 15%), but was wondering if there's
a ballpark % where you could get various coloring oxides under without
having to worry about leaching.

For instance, nobody has said anything bad about cobalt probably because
such a small amount go such a long way - 0.5% for a major blue.
But if I can make my glaze work with 5% copper carb (cone 5), would
I still need to worry? What about managanese dioxide? Is a coupla
% really going to be a problem?
TIA Grace

Fred and Grace Hatton, Hawley, PA