Tom Buck on fri 5 mar 99
CNC:
The point I tried to make in yesterday's post was that there is no
consensus on the safety of Barium in glazes; you use Barium (fritted or
otherwise) at your own risk and conscience. Using a frit vs raw carbonate
will not make any difference in the fired glaze: 1) The firing causes the
frit to be incorporated into the glass matrix itself; and 2) if the
glaze is unbalanced and attacked by food acids, then Ba++ ion will be
relased into the foodstuff.
Janet DeBoos's ongoing studies revealed that it is almost
impossible to predict how a glaze containing Barium will perform in
service, it might release too much Ba++ ion or the release may be too low
to measure, but one cannot say for sure without testing. And now that Dr
Hale at Alfred University will perform leach tests for $10 an ion, there
is little excuse for any conscientious potter not to have their
Barium-containing glaze tested for safety purposes.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
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