Neupet on wed 13 may 98
How about using spodumene and flourspar or calcium flouride for the flourine
that the spodumene is missing?
Lynne in Philadelphia
Tom Buck on thu 14 may 98
Lynne in Philly:
FLU/ORINE is element No. 9, it has a low atomic weight (19), and
there are usually four fluorine atoms in a lepidolite crystal
(fluoro-alumino-silicates: potassium (K), lithium (Li), Aluminum (Al),
plus Aluminum oxide (alumina) and Silicon oxide (silica). Fluorine
represents about 5% of the "Formula Weight".
Fluorspar (Calcium fluoride, CaF2) is also a crystalline substance
that melts at 1350 Celsius.
Since the CaF2 would not enter into the glass matrix until a quite
high temperature, and likely would be subject to Fluorine loss in a
reduction firing, it is difficult to see how adding Fluorspar to Spodumene
would substitute for the Fluorine in the Lepidolite crystal.
It could, of course, do just that, especially if the glaze mix
containing Spodumene and Fluorspar was balled milled for several hours to
disperse the Flurospar more widely in the mix. Worth a try, particularly
if the Lepidolite-containing glaze gave a special effect.
Good tests. Til later. Tom.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
On Wed, 13 May 1998, Neupet wrote:
> ----------------------------Original message----------------------------
> How about using spodumene and flourspar or calcium flouride for the flourine
> that the spodumene is missing?
> Lynne in Philadelphia
>
Craig Martell on thu 14 may 98
At 08:27 AM 5/13/98 EDT, you wrote:
>----------------------------Original message----------------------------
>How about using spodumene and flourspar or calcium flouride for the flourine
>that the spodumene is missing?
>Lynne in Philadelphia
Hi:
The absence of flourine is a good thing. It will gas and cause pits,
pinholing, and blisters in glazes. I don't think it contributes anything
beneficial to glazes and fluorine gas is a health hazard.
regards, Craig Martell-Oregon
JJHerb on sat 16 may 98
Might not cryolite, sodium aluminum fluoride, be a better choice as a source
of F. The mineral is softer and melts at 1000 C. Also has a little more
fluorine per molecular - six rather than two numerically - although on a
weight basis the fluorite is 50% F while the cryolite is 54% F. The main flux
in lepidolite is potassium so the sodium in the cryolite might be closer in
effect than the calcium in fluorite.
Like everyone always says, test, test. test.
Joseph Herbert
JJHerb@aol.com
Neupet on sat 16 may 98
You're right, but the reason to use it is for crater glazes where you want
pits, etc.
Lynne
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