rick Mace on fri 10 jan 97
I'm going to test a cone 10 glaze, CRG-34, Deep Ox-Blood CRG, from THE
POTTER'S COMPLETE BOOK OF CLAY AND GLAZES, by James Chappell. It's formula
is:
Feldspar (Buckingham) 56.5
Feldspar (Kingman) 20.0
Colemanite 10.5 (I'm using Gerstly Borate)
Whiting 11.4
Copper Oxide 0.3
Tin Oxide 1.0
Iron Oxide, Red 0.3
Bentonite 1.0
I'd like to know about substitutes for the Buckingham and the Kingman
Feldspars. I have Custer, G-200, and Kono F-4. I looked up all of them and
their make-up is listed here at the end, for the SiO2, Al2O3, Fe2O3, CaO,
MgO, K2O, and the Na2O, in each of them.
My question is, which of my three Feldspars would substitute? Or am I
picking at straws here and just using any one of my three would substitute
well for the Buckingham or the Kingman?
Looking at the main part, SiO2, perhaps I should use a couple of % less of
the Custer or G-200 to try and, at least, get the Silica closer to right?
Thank you, anyone, if you can help. I've just recently begun to experiment
with glazes. -- Rick Mace
SiO2:
G-200 -- 67.5
Buckingham -- 65.58
Custer -- 68.58
Kingman -- 66.0
Kono F4 -- 66.8
-------
Al2O3:
G-200 -- 18.5
Buckingham -- 19.6
Custer -- 17.5
Kingman -- 18.7
Kono F4 -- 19.7
--------
Fe2O3:
G-200 -- 0.09
Buckingham -- 0.01
Custer -- 0.08
Kingman -- 0.10
Kono F4 -- 0.04
-------
CaO:
G-200 -- 1.15
Buckingham -- 0.16
Custer -- 0.30
Kingman -- 0.10
Kono F4 -- 1.80
-------
MgO:
G-200 -- ---
Buckingham -- 0.2
Custer -- 0.01
Kingman -- ---
Kono F4 -- ---
------
K2O:
G-200 -- 9.4
Buckingham -- 12.44
Custer -- 10.4
Kingman -- 12.0
Kono F4 -- 7.0
-------
Na2O:
G-200 -- 3.24
Buckingham -- 2.56
Custer -- 3.0
Kingman -- 2.8
Kono F4 -- 4.5
------
I.L.:
G-200 -- 0.2
Buckingham -- 0.32
Custer -- 0.3
Kingman -- 0.2
Kono F4 -- 0.2
Talbott on sat 11 jan 97
>----------------------------Original message----------------------------
>I'm going to test a cone 10 glaze, CRG-34, Deep Ox-Blood CRG, from THE
>POTTER'S COMPLETE BOOK OF CLAY AND GLAZES, by James Chappell. It's formula
>is:
>
>Feldspar (Buckingham) 56.5
>Feldspar (Kingman) 20.0
>Colemanite 10.5 (I'm using Gerstly Borate)
>Whiting 11.4
>Copper Oxide 0.3
>Tin Oxide 1.0
>Iron Oxide, Red 0.3
>Bentonite 1.0
>
>I'd like to know about substitutes for the Buckingham and the Kingman
>Feldspars. I have Custer, G-200, and Kono F-4. I looked up all of them and
>their make-up is listed here at the end, for the SiO2, Al2O3, Fe2O3, CaO,
>MgO, K2O, and the Na2O, in each of them.
>
>My question is, which of my three Feldspars would substitute? Or am I
>picking at straws here and just using any one of my three would substitute
>well for the Buckingham or the Kingman?
>
>Looking at the main part, SiO2, perhaps I should use a couple of % less of
>the Custer or G-200 to try and, at least, get the Silica closer to right?
>
>Thank you, anyone, if you can help. I've just recently begun to experiment
>with glazes. -- Rick Mace
I think I may have tried the very same recipe. I would use either g-200 or
custer for the entire amount of feldspar. If I tried this it was several
years ago, and before we were getting a good reduction with our kiln. Good
luck - I think you will be pleased with it.
>
>SiO2:
>G-200 -- 67.5
>Buckingham -- 65.58
>Custer -- 68.58
>Kingman -- 66.0
>Kono F4 -- 66.8
>-------
>Al2O3:
>G-200 -- 18.5
>Buckingham -- 19.6
>Custer -- 17.5
>Kingman -- 18.7
>Kono F4 -- 19.7
>--------
>Fe2O3:
>G-200 -- 0.09
>Buckingham -- 0.01
>Custer -- 0.08
>Kingman -- 0.10
>Kono F4 -- 0.04
>-------
>CaO:
>G-200 -- 1.15
>Buckingham -- 0.16
>Custer -- 0.30
>Kingman -- 0.10
>Kono F4 -- 1.80
>-------
>MgO:
>G-200 -- ---
>Buckingham -- 0.2
>Custer -- 0.01
>Kingman -- ---
>Kono F4 -- ---
>------
>K2O:
>G-200 -- 9.4
>Buckingham -- 12.44
>Custer -- 10.4
>Kingman -- 12.0
>Kono F4 -- 7.0
>-------
>Na2O:
>G-200 -- 3.24
>Buckingham -- 2.56
>Custer -- 3.0
>Kingman -- 2.8
>Kono F4 -- 4.5
>------
>I.L.:
>G-200 -- 0.2
>Buckingham -- 0.32
>Custer -- 0.3
>Kingman -- 0.2
>Kono F4 -- 0.2
------------------------------------------------------------------------------
1ST ANNUAL CLAYARTERS' GALLERY-NAPLES, ME (Summmer 1997) {contact me
directly for more information}
Celia & Marshall Talbott
Pottery By Celia
Route 114
P.O. Box 4116
Naples, Maine 04055-4116
(207)693-6100 voice and fax
clupus@ime.net
Craig Martell on sun 12 jan 97
Rick: If you want to accurately duplicate this glaze, get analysis of
Buckingham and Kingman spars, and calculate the Seger formula of this glaze.
You can then satisfy the molecular formula with materials that are presently
available. I have old anaysis of both spars if you want them. If you don't
want to go to this much trouble, you can substitute feldspars that are
currently on the market and see what happens. If you like to calculate
glazes, you can do Seger formulas of any "new" glazes you get to see if they
are in the "ballpark" with regard to being balanced glasses etc.
Regards, Craig Martell-Oregon
Ron Roy on sun 12 jan 97
>----------------------------Original message----------------------------
>I'm going to test a cone 10 glaze, CRG-34, Deep Ox-Blood CRG, from THE
>POTTER'S COMPLETE BOOK OF CLAY AND GLAZES, by James Chappell. It's formula
>is:
>
>Feldspar (Buckingham) 56.5
>Feldspar (Kingman) 20.0
>Colemanite 10.5 (I'm using Gerstly Borate)
>Whiting 11.4
>Copper Oxide 0.3
>Tin Oxide 1.0
>Iron Oxide, Red 0.3
>Bentonite 1.0
>
>I'd like to know about substitutes for the Buckingham and the Kingman
>Feldspars. I have Custer, G-200, and Kono F-4. I looked up all of them and
>their make-up is listed here at the end, for the SiO2, Al2O3, Fe2O3, CaO,
>MgO, K2O, and the Na2O, in each of them.
Hi Rick,
Buck and Kingman are both potash spars - I would try subing g200 for the
following reasons. Buck spar was very close to G 200. Kingman has a bit
more K2O than Buck, G200 and Custer. 76.5% G200 leaves you a little short
of K2O but it may not matter. The glaze is a little short of SiO2 and it
will craze. You might try a line blend adding silica (5,10,15) to try and
stop the crazing but the expansion is quite high with all that KNaO -
12.25% or 0.38 mols.
Even adding 5% silica will improve the durability, at 15% durability is
fine. With the silica at + 15% you may not get crazing on some clays but I
doubt you will find a porcelin that will have a high enough contraction.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Lawrence L. Anderson on mon 13 jan 97
Rick,
Custer, Buckingham, 'G200 are potash spars. Kona-F4 is a soda spar in
this part of the country. Kingman is also a potash spar. If your
looking for a substitute for kingman I would pick a potash spar that
comes as close as possible to Kingmans oxide formulation as I could get.
Unless I'm missing something in your question? later, Larry
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