ROGER BOURLAND on sat 6 jul 96
I'm working with some interesting recipes of Joseph Grebanier. He uses
some materials that I cannot seem to find either a source for ordering or
a substitution material for. Would appreciate any suggestions. The
materials are: Maine Feldspar, Buckingham Feldspar and Georgia Kaolin.
Thanks,
Roger Bourland
medelman@facstaff.wisc.edu on sun 7 jul 96
Roger Bourland is running into some recipes with "golden oldie" feldspars
, no longer mined. Buckingham
Spar was around in the 40's and 50's, maybe a little later. Substitute gram
for gram with Custer spar, if you are lazy like me. Or, do a pretty please
to one of our generous glaze gurus on Clayart, who use cyber programmed
calculation and don't take as long as I would the old fashioned way.
Georgia kaolin is easily substituted by 6 tile kaolin or Kaopaque or even
E.P.K. Test all this of course.
I know nothing about Maine feldspar. If someone on the net knows if it is a
soda or potash spar, it might help Roger to substitute.
Testing is the way to go. Good luck. Bacia Edelman
Paula Coleman on mon 8 jul 96
>----------------------------Original message----------------------------
>some materials that I cannot seem to find either a source for ordering or
>a substitution material for. Would appreciate any suggestions. The
>materials are: Maine Feldspar, Buckingham Feldspar and Georgia Kaolin.
I believe that Georgia Kaolin can be ordered directly from Standard Ceramic
Supply in Pittsburgh. Tile 6 also works as a substitute for Georgia Kaolin.
Good luck.
--------------------------------------------------------------------
Paula L. Coleman Email: potter@comcat.com
Ceramic Artist Web: http://www.comcat.com/~potter/
Bucks County, PA, USA
Emily Pearlman on tue 9 jul 96
>----------------------------Original message----------------------------
>>----------------------------Original message----------------------------
>>some materials that I cannot seem to find either a source for ordering or
>>a substitution material for. Would appreciate any suggestions. The
>>materials are: Maine Feldspar, Buckingham Feldspar and Georgia Kaolin.
>
>I believe that Georgia Kaolin can be ordered directly from Standard Ceramic
>Supply in Pittsburgh. Tile 6 also works as a substitute for Georgia Kaolin.
>Good luck.
>
>--------------------------------------------------------------------
>Paula L. Coleman Email: potter@comcat.com
>Ceramic Artist Web: http://www.comcat.com/~potter/
>Bucks County, PA, USA
Hi All:
When kaolin is called for we use EPK or Gerogia, which ever we have. No
problem.
Emily
Emily Pearlman-Pottery (clayfeat@echonyc.com)
http://206.4.28.2/emilypearlman
Tony Hansen on wed 10 jul 96
>Georgia kaolin is easily substituted by 6 tile kaolin or Kaopaque or even
>E.P.K. Test all this of course.
EPK and Pioneer kaolin are roughly equivalent in plasticity, but 6Tile
is drastically more plastic. This means that high kaolin or thickly
applied glazes could shrink, crack and crawl.
Kaopaque is drastically less plastic than the others, it is a specially
processed delaminiated kaolin for casting and raw whiteness applications
and glazes low in kaolin could powder off, settle in the bucket, bond
poorly, and present other application related problems.
--
-----------------------------ooO-(_)-Ooo---------------------------
Tony Hansen, IMC, 134 UPLAND DRIVE, Medicine Hat, Alberta
T1A 3N7 Canada Phone:403-527-2826 FAX:527-7441 BBS:527-6074
email: thansen@mlc.awinc.com web: http://digitalfire.com/imc.html
PJLewing@aol.com on thu 18 jul 96
Took me a while to get to this, as I've been off doing a workshop.
The formula for Buckingham feldspar is:
CaO .02 MgO .03 K20 .73 Na20 .23 Al2O3 1.06 SiO2 6.03
The fluxes are similar to Custer, but the Al/Si ratio is more like G200.
I don't know what Maine feldspar is, but we used to use a feldspar from
Maine called Oxford. It's called for in a lot of the old Rhodes glazes.
There never was an Oxford mine- it was just picked up off the ground in the
form of rocks. You can see why the supply ran out. The formula is:
CaO .05 K2O .59 Na2O .36 Al2O3 1.17 SiO2 8.07
This is probably most similar to Kona A-3 ( is that still around?), but has
even more Al and Si and a higher ratio.
This is exactly why glaze calculation programs were invented. They would
allow you to do an exact substitution, and it really works!
Happy calculating!
Paul Lewing, Seattle
Tom Buck on wed 20 aug 97
Jean Lehman: Seems your server was offline on Friday, etc. So my
message about feldspars never reached you.
In essence the two feldspars you cited are almost identical (NC4
and Kona F-4). The differences are 1% or less for most oxide components,
and this is usually well within normal mixing errors, or mineral analyses.
So use the two interchangeably. Good tests.
Tom Buck ) Hamilton, Ontario, Canada
Betty Burroughs on sat 5 sep 98
Can anyone on Clayart tell me if Custer and Kingman feldspars are notably
different or can they be used interchangeably in a recipe? Most recipes call
for Custer spar, I notice, but I have about 3 kilos of Kingman that I've had
for years.
_____________________________
Betty Burroughs
Victoria, BC
Canada
Earl Brunner on sun 6 sep 98
In a message dated 9/5/98 9:23:17 AM Pacific Daylight Time,
bettyb@brookenet.com writes:
<< Most recipes call
for Custer spar, I notice, but I have about 3 kilos of Kingman that I've had
for years. >>
If you only have 3 or so kilos, just mix it into a larger quantity of the
other spar, you will probably see little or no difference.
Earl
Donald G. Goldsobel on sun 6 sep 98
The late, great potter, Viveka Heino, advised using G200 as a straight
substitue for kingman. I have tried the same with Custer and my glazes are
not so sensitive to know the difference. The G200 is readily available here
in LA from Laguna, as is the Custer.
At 12:19 PM 9/5/98 EDT, you wrote:
>----------------------------Original message----------------------------
>Can anyone on Clayart tell me if Custer and Kingman feldspars are notably
>different or can they be used interchangeably in a recipe? Most recipes call
>for Custer spar, I notice, but I have about 3 kilos of Kingman that I've had
>for years.
>
>
>_____________________________
>Betty Burroughs
>Victoria, BC
>Canada
>
Rick Sherman on sun 6 sep 98
---------------------you ask------------------------------------------
Can anyone on Clayart tell me if Custer and Kingman feldspars are
notably different or can they be used interchangeably in a recipe? Most
recipes call for Custer spar, I notice, but I have about 3 kilos of
Kingman that I've hadfor years.
_____________________________
Betty Burroughs
Victoria, BC
Canada
--------------------reply---------------------------------------------
I have used both Custer and G-200 feldspares interchaeabley in the
exact same proportions as Kingman with no problem. I am certain some of
the real glaze experts can give you the breakdown of each. I have been
using those two plus Kona F4 for most of my glazes for years. I rememer
my professor had a vast range of felspars in the lab and would use
about three in every gaze formula he concocted. Can't find most of them
now.
Rick Sherman
San Jose, CA USofA
sherman@ricochet.net
Paul Lewing on sun 6 sep 98
Betty,
Custer is K2O .66, Na2O .30, CaO .03, Fe2O3 .01, Al2O3 1.04, SiO2 7.10
Kingman, K2O .73, Na2O .26, CaO .01, Fe2O3 .00, Al2O3 1.05, SiO2 6.29
They are (or were, before the Kingman mine closed) about as close to
each other as feldspars get. I've substituted straight across with no
discernable change.
Paul Lewing, Seattle
Ron Roy on sun 6 sep 98
Hi Betty,
There are two answers here. The last feldspar mined at Kingman were not up
to scratch - too refractory. If you have some of that it would be best to
dump it. If you care to test it then you can compare it to the Custer or
G200. Make a ball of each - about the diameter of a dime - it won't hold
together very well so set them on a tile right away. Spit is the best
medium I have found to help make the ball - then fire them - or you could
make a little pile on a tile. The ball has the advantage of showing
deformation. Fire them up to cone 6, or 8 or best 10. You can then see if
they are similar in melting power.
Here are the 3 molecular formulas.
There are many factors to compare. Because the fluxes are in unity (add to
1.0) then it is easiest to compare the alumina and silica amounts, the
ratio and expansion rates. Overall the normal Kingman (before it degraded)
is closer to G200 rather than Custer but for many balanced glazes -
especially those with lower amounts of feldspar (below 40%) the results
would be similar with a substitution of either. Better test with a small
batch first though.
KINGMAN SPAR
FORMULA & ANALYSIS
------------------
*CaO........ .09 .99%
*K2O........ .67 11.92%
*Na2O....... .23 2.68%
Fe2O3...... .00 .08%
AL2O3...... .96 18.28%
SiO2....... 5.87 66.05%
RATIO 6.14
EXPAN 652.03
WEIGHT 533.37
CUSTER SPAR
FORMULA & ANALYSIS
------------------
*CaO........ .03 .30%
*K2O........ .66 10.11%
*Na2O....... .30 3.03%
Fe2O3...... .01 .15%
AL2O3...... 1.04 17.18%
SiO2....... 7.14 69.23%
RATIO 6.85
EXPAN 585.45
WEIGHT 619.01
G 200 SPAR
FORMULA & ANALYSIS
------------------
*CaO........ .08 .81%
*K2O........ .64 10.69%
*Na2O....... .28 3.01%
Fe2O3...... .00 .08%
AL2O3...... 1.02 18.44%
SiO2....... 6.32 66.97%
RATIO 6.17
EXPAN 615.57
WEIGHT 566.45
The best way to substitute materials is to do it on a molecular level using
the Seger unity formula - you do need the analysis for the materials. If
not then you have to test by fire.
RR
>----------------------------Original message----------------------------
>Can anyone on Clayart tell me if Custer and Kingman feldspars are notably
>different or can they be used interchangeably in a recipe? Most recipes call
>for Custer spar, I notice, but I have about 3 kilos of Kingman that I've had
>for years.
>Betty Burroughs
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Tom Buck on mon 7 sep 98
Others no doubt will discuss the nature of Kingman fs (like Buckingham
fs, no longer mined). My reminder is that the standard Feldspars
(felspars) are generally high in K2O (potassia) or high in Na2O. Most
such FS's have this compositional proportions: 1 mole flux oxides, 1 mole
alumina, 6 moles silica. The variation from one to another is how much
silica is present, the range can be 5.5 to 7.2 moles (neph sy, not a true
feldspar, is 4 moles silica).
Most high-fire glazes behave well with one-for-one feldspar
substitutions while some C5-7 mixes may not be so forgiving.
In North America the two common Potash FS's are G-200 (in Eastern
NA, and Custer (in Western NA). Custer has more silica than G-200
otherwise the two are quite similar. A popular Soda spar is Kona F-4 and
it is a 1:1:6 type.
One can use either K or Na spars in most glaze; a distinction
shows up chiefly in copper reds and similar colours needing reducing
conditions. K-spars impart of bluish (purplish) tone to copper reds
whereas Na-spars bring the tone into the orange part of the spectrum.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
Rick Sherman on wed 30 sep 98
There was some great information on Feldspars. Ron was there to make
certain we understand Kona F4 is a soda spar and Craig gave a great
outline for those new to glazes as to the role of feldspars in glazes.
Now, he is taking a nap with Parmelee.
Ron mentioned that there were [and possibly are] more feldspars than
Custer, G200 and F4. I know Kingman and Buckingham have gone the way of
Albany slip and ditto for Keystone. Here is a list of some others. Does
anyone know if they are still about?
Bainbridge Spar
Clinchfield Spar [ 202 & 203]
Del Monte Spar
Godfrey Spar
Kona A3
Modoc Spar
Maine Spar
Minpro Spar
Oxford Spar
Wonder if any of the glaze gurus have leads on these.
Rick Sherman
San Jose, CA USofA
sheman@ricochet.net
Grimmer on thu 1 oct 98
Rick,
I got a bag of Minpro NC-4 about a year ago from Great Lakes Clay in
Illinois about a year ago. Pretty close to Kona F4, ie, a soda spar. Alas an
analysis is not at hand. On the hard drive somewhere. Also, K-200 is still
around, I believe. It's a real high (.72 mol. eq.) Potassium spar, good for
blue celedons.
stev grimmer
marion illinois.
they're harvesting all the corn and beans with their
"threshers two lanes wide."
----------
>From: Rick Sherman
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: Feldspars
>Date: Wed, Sep 30, 1998, 8:29 AM
>
>----------------------------Original message----------------------------
>There was some great information on Feldspars. Ron was there to make
>certain we understand Kona F4 is a soda spar and Craig gave a great
>outline for those new to glazes as to the role of feldspars in glazes.
>Now, he is taking a nap with Parmelee.
>
>Ron mentioned that there were [and possibly are] more feldspars than
>Custer, G200 and F4. I know Kingman and Buckingham have gone the way of
>Albany slip and ditto for Keystone. Here is a list of some others. Does
>anyone know if they are still about?
>
>Bainbridge Spar
>Clinchfield Spar [ 202 & 203]
>Del Monte Spar
>Godfrey Spar
>Kona A3
>Modoc Spar
>Maine Spar
>Minpro Spar
>Oxford Spar
>
>Wonder if any of the glaze gurus have leads on these.
>
>Rick Sherman
>San Jose, CA USofA
>sheman@ricochet.net
Wade Blocker on tue 25 jul 00
Dear Alisa,
The descriptioon of Forshammer spar sounds just like the description for
Custer "a potash feldspar with a mid-range soda/potash ratio"
Here is a feldspar analysis chart:
silicon alumina iron calcium magnesium sodium potassium loss on
dioxide oxide oxide oxide oxide oxide oxide ignition
Name Si02 Al203 Fe203 Ca0 Mg0 Na20 K20 l
Custer 68.5 l7.5 0.08 0.03 trace 3.00 10.4 0.3
G 200 67.5 l8.5 0.09 1.15 3.24 9.4 0.2
Primas P 66.5 l8.5 0.077 3.50 10.31 0.1
Primas S 68.5 17.0 0.375 0.40 6.40 5.40 0.1
Primas potash and Primas sodaspar are from Mexico and cheaper than other
feldspars. I have used Prima S when Kona spar ( a soda spar)was
unavailble.
Hope this is what you wanted. Mia in hot ABQ
Joseph Herbert on thu 27 jul 00
Feldspars are a major group of rock forming minerals, among the most common
in the crust of the earth. The feldspars are what make granite pink or
gray, as the case may be. The possible compositions of feldspars is fairly
broad. In the Orthoclase (potassium) Albite (sodium) line there can be a
pretty much continuous substitution of one ion for the other. Potassium is
+1 and sodium is +1 so the only issue is size. The crystal structure can
accommodate the change in sizes and does. Mostly there is always some
potassium in soda feldspar and always some soda in potassium feldspar.
There is also a sodium to calcium line of feldspars that is more interesting
chemically because the sodium is +1 and the calcium is +2. There is a
continuous range of compositions here too but as the sodium/calcium ratio
changes, the Alumina/silica ratio changes also. The Alumina increases at
the expense of silica to absorb the extra + charge as the calcium increases.
The calcium feldspars are dark and sometimes show iridescence that is very
beautiful.
This is all fine but we really only care about the feldspars that someone
grinds up for us and they (the grinders) decide what is available. It is
nice to think about using some particular feldspar composition but unless
you guy some really noisy machines, you have to use what someone else
grinds.
One of the consequences of the changing Alumina/silica ratio is a change in
the weathering products. I think that orthoclase - potassium feldspar tends
to weather to Kaolin. The calcium feldspars weather to other clays.
(orthoclase - other clays Ho HO)
Crystal chemistry is a wonderful thing - much trendier that asking what your
major is.
Joseph Herbert
Don & June MacDonald on wed 11 dec 02
Could someone with a computer glaze program please tell me what the
difference between Calspar soda spar and KF-4 soda spar is?
Also, is there any information on how close Kingman Feldspar is to
either G200 or Custer? I know these are potash feldspars.
Thank you!
June from B.C.
Ababi on thu 12 dec 02
To make it easier for me and for you I give you two links:
One near you:
http://digitalfire.com/material/index.htm
The other Less details but easier to navigate
http://www.matrix2000.co.nz/MaterialsWeb/default.htm
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
---------- Original Message ----------
>Could someone with a computer glaze program please tell me what the
>June from B.C.
Tom Buck on thu 12 dec 02
June< Hi, hope you are well.:
you are asking about spars that have petered out.
Calspar N : 77.3%w SiO2; 13.8% Al2O3; 7.4% NA2O; 0.1% K2O; 0.4% CaO;
0.2% Fe2O3; LOI, 0.6%
Kingman spar: 66.0% SiO2; 18.7% Al2O3; 2.8% Na2O; 12.0% K2O; 0.1% CaO;
.1%Fe2O3; LOI 0.2%.
Add the Na2O+K2O for Kingman and you get 14.8% alkali oxides; G-200 has
13.6% alkali oxides (KNaO); Custer has 13.0% KNaO. so you can see, the
KNaO is a bit lower for the current potspars. in many recipes for midfire
and highfire this difference will not be significant because the CaO is
higher and likely will compensate.
As for Calspar N and Kona F-4, the big difference is the SiO2 and Al2O3
content: 77.3 SiO2 for Calspar N and 67.5 SiO2 for F-4; and 13.8 Al2O3
for C/N and 19.4 for F-4.
So F-4 would yield a more viscous melt were it not for its much
higher KNaO, 12.5% vs C/N's 7.5%. you will need glzcalc to update a recipe
with Calspar N in it.
TIL LATER. PEACE. TOM.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
On Wed, 11 Dec 2002, Don & June MacDonald wrote:
> Could someone with a computer glaze program please tell me what the
> difference between Calspar soda spar and KF-4 soda spar is?
>
> Also, is there any information on how close Kingman Feldspar is to
> either G200 or Custer? I know these are potash feldspars.
>
> Thank you!
>
> June from B.C.
>
> ______________________________________________________________________________
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