Joseph Herbert on sat 24 may 97
For Laurie Cowell:
Fluorspar is undoubtedly fluorite a calcium fluorine mineral - CaF2. In the
kiln this gives off the fluorine gas which goes up the flue, which there
better be one of. This is often used in crater glazes because the gas
liberated makes bubbles that break.
Lepedolite is lithium mica. It is a hydrated aluminum silicate that contains
lithium. If you have read some of the spodumene discussions in the past few
months, you might be glad to have this. There aren t many chemical toxicity
issues with this compound unless you have already been loaded up by your
therapist with other lithium and then you start drinking glaze slurry. So
that s like 50/50, right?
Kryolite - probably cryolite - is a sodium-aluminum fluorite that made
aluminum beer cans possible. This is the material that acts as a flux in the
electrical furnace refining of bauxite. Before the development of the Hall
process, aluminum metal was very expensive - more than platinum - and was
made into jewelry and the capstone of the Washington Monument. This material
has a refractive index of 1 so it "disappears" in water. It also gives off
fluorine gas when in the kiln.
Petalite - a lithium mineral - probably the cautions as lepedolite.
Don t know about the "vamadium" probably some vanadium compound. This
probably requires some caution. Depending of what the vanadium is compounded
with, it could be pretty toxic. But it makes things yellow.
Joe - now cut off in the outer darkness
JJHerb@AOL.com
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