Roeder on sun 24 nov 96
Hello All
I just started unpacking an order of new glaze chemicals, and I noticed a
big change in the appearance of the Spodumene.
The "old stuff" in my studio was gray in color....the new stuff is white and
has sparkles (like ground glass or fake snow glitter). What have I
received?? I ordered it from A.R.T. as I did the last time (3-4 years ago).
Is there a new source for spodumene? Am I going to have problems getting
the same glaze results I used to? Is there an ordering source for the "gray
stuff"?
It seems there was a spodumene/chemical grade thread on the list some time
ago. I wish I could search the archives to avoid a re-hash....
Any insight would be appreciated. TIA
Candice Roeder
rural Michigan
"Rafael Molina-Rodriguez (Rafael Molina-Rodriguez)" on mon 25 nov 96
Candice :
I had the same experience this past week. I called the local Clay
supplier, Trinity Ceramic Supply, and inquired about the appearance of
the spodumene; white, course, and granular. Angela, at Trinity,
informed me that the new source for spodumene is from Australia. She
assured me that it will behave the same way as the old spodumene, the
fine gray powdery material.
Rafael
rmr3431@dcccd.edu
>>> Roeder 11/24/96 10:39am >>>
----------------------------Original message----------------------------
Hello All
I just started unpacking an order of new glaze chemicals, and I noticed a
big change in the appearance of the Spodumene.
The "old stuff" in my studio was gray in color....the new stuff is white
and
has sparkles (like ground glass or fake snow glitter). What have I
received?? I ordered it from A.R.T. as I did the last time (3-4 years ago).
Is there a new source for spodumene? Am I going to have problems
getting
the same glaze results I used to? Is there an ordering source for the
"gray
stuff"?
It seems there was a spodumene/chemical grade thread on the list some
time
ago. I wish I could search the archives to avoid a re-hash....
Any insight would be appreciated. TIA
Candice Roeder
rural Michigan
Craig Martell on mon 25 nov 96
Yes, there have been some changes as to what is available on the market.
Some years ago Foote Minerals stopped marketing Ceramic Grade Spod and the
only type of Spod that we could get was Chemical Grade, which is a bit
different than Ceramic.
Now there are new sources of Ceramic Grade on the market. It sounds as if
your old stuff may be Chemical Grade, and the new stuff could be one of the
new sources of Ceramic Grade Spod (which IMO is much more preferable than
Chemical Grade). It would be advisable to contact ART and ask them for some
info on the new material. I would also recommend testing before mixing large
batches of glaze with the new material.
Regards, Craig Martell-Oregon
COOPJ@aol.com on mon 25 nov 96
Candace,
Yes, indeed the Spodumene sources have changed again. Foote Chemical used to
be the major supplier of Lithium materials in the USA. Foote quit supplying
Spodumene about a year or two ago . Most suppliers are now selling Australian
Spodumene. The Foote Spodumene was higher in iron oxide and so could account
for the color difference. I think you will find that the Australian material
is probably purer than the older material and may fire whiter. If this is
objectionable you can add some iron oxide to it. Some of us "old timers "
used to buy the lower iron Ceramic Grade Spodumene from Foote in the early
1980's and sreamed when they started selling the higher iron grade. The
Australian material is actually more like the good old stuff. I guess every
thing works in cycles even Ceramic chemicals.
Jim Cooper
Akita-jin \"Lee Love\" on tue 26 nov 96
The "new" spodumene does not work that same as the "old." My standbye
shino is not as warm with the new spodumene. It is now white and glassy
looking. I think it has less iron in it. I have tried added 1% and
..5% R I OX and found that this gives back some warmth, but it is
spotty. Because this glaze is pretty stable, I'm going to try and add a
little RedArt next, hoping this will disperse the iron better.
Lee
====================================================
/(o\ Lee Love In "St. Paul", MN ' Come see some pixs of my AkitaPup:
\o)/ mailto:LeeLove@millcomm.com ' http://www.millcomm.com/~leelove
mailto:AkitaJin@Cryogen.com ' "It gets late early out there."
-Yogi Berra-
William Amsterlaw on tue 26 nov 96
For Candice Roeder:
There was a discussion on spodumene around Feb 1996. Although nobody had a
specific chemical analysis comparing the older gray material with the newer
Australian white material, the following remarks were made:
About the older grey stuff:
* Now in short supply
* Contains more lithium and iron and acts as a stronger flux.
* Foamy: A process used to separate the spodumene from other minerals involves
addition of soap which will cause this form of spodumene to cause foamy glaze
mixes. Several suggestions were made for eliminating the foam: (1) calcine
the spodumene; (2) add silicon defoamer obtainable from swimming pool
maintenance companies; (3) wait several weeks after the glaze is mixed and
the foaming tendency goes away by itself; or (4) Rinse the glaze mix by
repeatedly adding excess water, letting the glaze resettle, and then siphoning
off water.
------------------------------
On 24 Nov 1996 Candice Roeder wrote:
I just started unpacking an order of new glaze chemicals, and I noticed a big
change in the appearance of the Spodumene. The "old stuff" in my studio was
gray in color....the new stuff is white and has sparkles (like ground glass or
fake snow glitter). What have I received?
Richard Burkett on wed 27 nov 96
In response to a variety of questions about the new Australian spodumene:
Once again, I set up the CeramicsWeb Materials Database to answer just this
type of question. PLEASE use it. Feel free to repost analyses here if that's
appropriate. That's why it's there.
Here are a few analyses that should help you deal with this problem and
understand what the chemical differences really are and make adjustments for
the fact that it has more lithium oxide (suggesting a lower melting point)
and less iron oxide (possible color changes):
Spodumene (theoretical)
Silica/Alumina ratio: 4:1
Equivalent Molecular Weight: 372.060
Molecular Formula of Spodumene (theoretical):
Li2O 1.000 Al2O3 1.000 SiO2 4.000
Percentage Analysis
64.57 % SiO2
27.40 % Al2O3
8.03 % Li2O
______________
100 % TOTAL
Spodumene (Foote Minerals, 200 mesh)
Silica/Alumina ratio: 4.3:1
Equivalent Molecular Weight: 478.683
Molecular Formula of Spodumene:
K2O 0.060 Al2O3 1.176 SiO2 5.070
Na2O 0.005 Fe2O3 0.069
Li2O 0.935
Percentage Analysis
64.88 % SiO2
25.54 % Al2O3
1.21 % K2O
0.06 % Na2O
5.95 % Li2O
2.35 % Fe2O3
______________
100 % TOTAL
Spodumene (Australian)
Silica/Alumina ratio: 4.0:1
Equivalent Molecular Weight: 387.238
Molecular Formula of Spodumene (Australian):
K2O 0.008 Al2O3 1.034 SiO2 4.158
Na2O 0.013 Fe2O3 0.002
Li2O 0.979 P2O5 0.007
Percentage Analysis
64.48 % SiO2
27.21 % Al2O3
0.20 % K2O
0.20 % Na2O
7.56 % Li2O
0.26 % P2O5
0.09 % Fe2O3
______________
100 % TOTAL
Comments:
Supplier:
F&S Alloys & Minerals Corp.
605 Third Ave.
New York, NY 10158
(212) 490-1356
Manufacturer:
Gwalia Consolidated Ltd.
Perth, Australia
(formerly Lithium Australia)
Richard Burkett - School of Art, Design, & A.H, SDSU, San Diego, CA 92182-4805
E-mail: richard.burkett@sdsu.edu <-> Voice mail: (619) 594-6201
Home Page: http://rohan.sdsu.edu/dept/rburkett/www/burkett.html
CeramicsWeb: http://apple.sdsu.edu/ceramicsweb/index.html
Craig Martell on wed 27 nov 96
Hi All: There seems to be a lot of interest in Lithium compounds lately,
such as the difference between Chemical and Ceramic grade Spodumene.
Personally, I won't use the Chemical Grade stuff. Shino glazes made with
chemical grade look muddy to me. Fire fusion buttons of Chemical and Ceramic
to cone 10 or whatever your end point is and compare. Anyway, this is just
my personal preference not an axiom. I do however have %analysis of both and
will share them with whomever is interested. They are as follows:
Chemical Grade Spodumene
Si-Al ratio 4.32 to 1
SiO2 63.00%
Al2O3 24.80
Fe2O3 2.00
K2O 1.18
Na2O .60
Li2O 5.70
Ceramic Grade Spodumene
Si-Al ratio 4.14 to 1
SiO2 63.70%
Al2O3 26.15
Fe2O3 .65
K2O .60
Na2O .32
Li2O 6.88
It appears that Chemical Grade Spod may also contain a very small amount of
Phosphorous Pentoxide, about .08%. Sorry, but I don't have any kind of
analysis on the Australian Spod. maybe one of the suppliers will give
someone, who wants to know the info.
Regards, Craig Martell-Oregon, on my last bag of Foote Minerals Ceramic
Grade
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