Gary Carlson on wed 22 oct 97
Hi,
I'm a new subscriber to Clayart, so I apologize if this question has been
asked and answered a hundred times before. I have been using a glaze (St.
John's yellow-brown, cone 10 oxidation) containing 2.5% barium carbonate for
many years. I'm concerned about its toxicity, an issue I did not appreciate
years ago when I started using it. I have heard that glazes containing less
than about 10% (?) barium carbonate should be safe for use with food, because
the barium is held tightly in the glaze (as it would be in a frit). But I
haven't found any reference that says this, and I'm concerned. I have been
using dishes and bowls with this glaze on the food-contacting surface for
about 25 years, and I think I'm still in good health--but I would like to
find out so I can use the dishes without concern, or get rid of them. Also,
I've heard you can have the toxicity of glazes checked, but I don't know who
does this. I do know you can replace barium carbonate with strontium
carbonate and get rid of any problems, but I'd rather not trash a whole lot
of plates if it's not necessary.
Any comments/references on barium carbonate toxicity at low concentrations
and on testing labs (cost?) to check it would be much appreciated.
Thanks, Gary Carlson
Albuquerque, N.M.
Don Prey on thu 23 oct 97
Gary, your best bet right now is to read the article in the Sept. 97 issue of
Ceramics Monthly..."Is Barium Carbonate Safe?" by Jeff Zamek.
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