John Britt on sun 28 nov 99
II looked up the Chemical analysis of Zinc Oxide :
ZnO -99.5
Pb - 0.05
Fe - 0.02
Cd - 0.01
S - 0.02
HCl - 0.1 (Insoluble)
Magnetic Iron - 5ppm
(Largest consumer is the rubber industry 50%)
This is from "Out of the Earth into the Fire" by Obstler.
I guess that explains why there is concern about lead contents.
This book gives an excellent discussion of the use of Zinc in glazes,
indication that the presence of zinc in recipes may be a carry over from
oxidation recipes. They discuss its toxicity and question its use in
reduction glazes. (Quoting Hamer and Hamer) And much more... that I
will leave you to read for yourselves. Pg. 183-185.
--
Thanks,
John Britt claydude@unicomp.net
Dys-Functional Pottery
Dallas, Texas
http://www.dysfunctionalpottery.com/claydude
http://www.silverhawk.com/ex99/britt/welcome.html
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