Barry Chlypavka on fri 9 may 03
I have a classic problem, glazes that I want to use don't quite match up.
I need to adjust a cone 10 glaze, down to an 8-9 cone glaze.
It is a satin black glaze made to fire in oxidation. It is an 8-10 glaze
but bubbles up at 9 and won't correct itself until cone 10 down hard. The
recipe is as follows.
F4> 5
custer> 3
dolomite>3
talc> 3
whiting> 0.4
Ball clay> 2
Silica. 3.6
standard black oxide load.
My weakness is understanding which ingredients could or should be altered
to get about a cone and a half lowering. Reduce alumina or increase flux,
or both and approximately how much. I need starting points and will of
course do the testing.
Lily Krakowski on fri 9 may 03
Quick primitive, and probably good solution. Do TWO straight line blends.
In one replace the F4 with Neph Sy, in the other replace the Custer with
Neph Sy. If one blend does not produce the answer, combine the two best and
do another straight line blend replacing the F4/Custer with neph sy. (In
other words if the best of one blend is F4 3 and the other Custer 1, make up
the glaze with F4 3 and Custer 1 and then straight line blend with NephSy.)
But I bet someone will calculate it for you!
Barry Chlypavka writes:
> I have a classic problem, glazes that I want to use don't quite match up.
> I need to adjust a cone 10 glaze, down to an 8-9 cone glaze.
> It is a satin black glaze made to fire in oxidation. It is an 8-10 glaze
> but bubbles up at 9 and won't correct itself until cone 10 down hard. The
> recipe is as follows.
>
> F4> 5
> custer> 3
> dolomite>3
> talc> 3
> whiting> 0.4
> Ball clay> 2
> Silica. 3.6
> standard black oxide load.
>
> My weakness is understanding which ingredients could or should be altered
> to get about a cone and a half lowering. Reduce alumina or increase flux,
> or both and approximately how much. I need starting points and will of
> course do the testing.
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Ababi on fri 9 may 03
Hello Barry Chlypavka
First your recipe into 100%
20X 5
BARRY CHLYPAVKA'S GLAZE
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 1 1305 deg.C. -
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
F-4 Feldspar 25.00
Custer feldspar 15.00
Dolomite 15.00
talc Nital 15.00
Calcium Carbonate 2.00
OM-4 Ball Clay 10.00
silica 18.00
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Seger Weight%
KNO 0.166 5.62%
CaO 0.368 8.93%
MgO 0.466 8.12%
Al2O3 0.263 11.59%
SiO2 2.524 65.61%
TiO2 0.004 0.13%
K2O 0.084 3.41%
Na2O 0.082 2.21%
Al:Si 9.60
Expan. 6.59
ST 379.70
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
The silica alumina level is of ^6. I belive it is a magnesium matte glaze.
It has a very high magnesia.
I suggest you to make line blends or easier, try as follow some tests
your base less 5% talc 10 and without reducing the clay
I did not understand what was: >standard black oxide load.
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 ----------
>I have a classic problem, glazes that I want to use don't quite match up.
>I need to adjust a cone 10 glaze, down to an 8-9 cone glaze.
>It is a satin black glaze made to fire in oxidation. It is an 8-10 glaze
>but bubbles up at 9 and won't correct itself until cone 10 down hard. The
>recipe is as follows.
>F4> 5
>custer> 3
>dolomite>3
>talc> 3
>whiting> 0.4
>Ball clay> 2
>Silica. 3.6
>standard black oxide load.
>My weakness is understanding which ingredients could or should be altered
>to get about a cone and a half lowering. Reduce alumina or increase flux,
>or both and approximately how much. I need starting points and will of
>course do the testing.
Brian Guffey on fri 9 may 03
a good start would be to increase the amount of flux in the glaze ... or =
alter it ... your custer is a ^10 flux, if you replace some of that ... i=
f not all of it ... with say neph sy (a ^7) flux, that should reduce the =
melting temp of the glaze ... and looking over it again ... theres 8 par=
ts feldspar all together ... thats ... roughly 40% off the top of my head=
is a ^10 flux, you could definanly chance some of the feldspare whether =
the f4 or custer into neph sy and still keep it at the same amount of stu=
ff.
----- Original Message -----
From: Barry Chlypavka
Sent: Friday, May 09, 2003 1:14 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Lowering glaze temp
I have a classic problem, glazes that I want to use don't quite match up.
I need to adjust a cone 10 glaze, down to an 8-9 cone glaze.
It is a satin black glaze made to fire in oxidation. It is an 8-10 glaze
but bubbles up at 9 and won't correct itself until cone 10 down hard. The
recipe is as follows.
F4> 5
custer> 3
dolomite>3
talc> 3
whiting> 0.4
Ball clay> 2
Silica. 3.6
standard black oxide load.
My weakness is understanding which ingredients could or should be altered
to get about a cone and a half lowering. Reduce alumina or increase flux,
or both and approximately how much. I need starting points and will of
course do the testing.
_________________________________________________________________________=
_____
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclin=
k.com.
Barry Chlypavka on sun 11 may 03
To everyone. I guess I had not understood how to find your responses, but
have it now. I have had help off-board too, thanks.
Answers to question. Sharon,
black oxide load
cobalt ox, .6
Red Iron ox .6
Manganese d. .4
Chrome ox, .2
I will take Lily and Brian's suggestions to replace cust and or F4 with
neph sy.
I will throw together a small batch of other glazed pots to try at the
lower cone 9 in the regular cone 10 elec kiln. My teeny test kiln never
works for a high fire test on satin glazes, a lesson finally learned, it
cools too fast to go satin.
I will get back with the results. Further input will be appreciated.
Barry
Tony Hansen on mon 12 may 03
I would replace all the dolomite and talc and
as much as possible of the whiting with a high
MgO frit. Replace any remaining whiting with
wollastonite. Check the bottom of this page for
a good example of how well this works.
http://digitalfire.ab.ca/cermat/education/4.php
F4> 5
custer> 3
dolomite>3
talc> 3
whiting> 0.4
Ball clay> 2
Silica. 3.6
standard black oxide load.
Tony Hansen
| |
|
