Peggy Thompson on mon 19 dec 11
How is Tbs zinc used on pecans opposed to zinc for ceramic differ and
is it adaptible for glazing use?
Same for lime or whiting calcium carbonate?
Art school college failed to offer chemistry, sorry for my ignornce.
Dick White on mon 19 dec 11
Peggy, the zinc used in pottery glazes is zinc oxide, which has the chemi=
=3D
cal
formula ZnO, one zinc atom together with one oxygen atom. The zinc compou=
=3D
nds
used in agriculture are usually zinc chelate or zinc sulfate. The chelate=
=3D
is
an complex organic molecule (having various numbers of carbon and hydroge=
=3D
n
atoms plus others) with a zinc atom wedged in. The sulfate has the chemic=
=3D
al
formula ZnSO4, one zinc, one sulfur, and four oxygens. I suppose you coul=
=3D
d
use the agricultural zincs in glazes, but you would need to adjust the
amount of the raw material used to obtain the correct proportion of zinc =
=3D
in
the final melted glaze. You would also be introducing other elements that=
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might affect the glaze in unknown ways.
As for the limestone, it is possible that a bag of agricultural lime is
chemically straight calcium carbonate, the same as whiting. Or the
agricultural lime might be dolomitic limestone, which is about 45% magnes=
=3D
ium
carbonate with the calcium carb. Even if you could be certain of the
chemical analysis of the agricultural lime, the farm product is probably =
=3D
not
ground as finely.
dw
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