Wanda Holmes on mon 1 apr 02
I tested Richard Behren's Satin Matt Cone 6 glaze and fell in love with the
waxy semi-matte surface. However, it leached badly in a 3-day vinegar test.
So, I set about to make it more durable. Despite my efforts, the "improved"
glaze still leaches almost as badly. Any insight any of you can offer would
be most appreciated.
The original recipe was:
Feldspar (I used Custer) 34.9
Whiting 12.62
Zinc oxide 25.8
EPK 4.10
Silica 22.6
.5 Cobalt carbonate added
The chemical formula is:
Na2O .03
K2O .08
MgO .00
CaO .25
ZnO .64
Al2O3 .15
SiO2 1.6
P2O5 .00
TiO2 .00
Fe2O3 .00
Al:Si 1:10.92
My improved recipe is:
Custer feldspar 25.8
Whiting 5.2
Zinc Oxide 18.6
EPK 9.3
Silica 26.7
Ferro Frit 3124
Cobalt carbonate .5
With a chemical formula of:
Na2O .07
K2O .08
MgO .00
CaO .24
ZnO .61
Al2O3 .25
SiO2 2.52
P2O5 .00
TiO2 .00
Fe2O3 .00
Al:Si 1:10.28
My strategy was to get it within the limits set out by Ron & John in
"Mastering Cone 6 Glazes", boost the alumina and silica up into the durable
range, keep the Al:Si ratio near the original values, & keep the fluxes near
their original values.
The surface quality of the new glaze is very like the original. The color
response is a bit less intense. Once again, it is a thing of beauty, but
not durable. Should I just keep boosting up the Al & Si until I find a
durable result or ruin the surface quality, whichever comes first?
Wanda
Ababi on tue 2 apr 02
I think it is a wrong way to judge Behrens's glazes the way we do to
our new glazes, trying to pass them the rules of J&R.
MATT GLAZE BEHRENS
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 6 1222 deg.C. -
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Custer feldspar 34.90
ZINC OXIDE 25.80
EPK Kaolin 4.10
SILICA 22.60
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Seger Weight%
KNO 0.146 5.28%
CaO 0.005 0.12%
ZnO 0.849 29.74%
Al2O3 0.198 8.69%
SiO2 2.171 56.15%
TiO2 0.001 0.02%
K2O 0.100 4.06%
Na2O 0.046 1.22%
Al:Si 10.95
Expan. 7.12
ST 377.26
It is screaming from the recipe that we have too much zinc. So if you
want a matte milky glaze make or look for such.
If you like this glaze use it for what it has.
See in the books. What does zinc make to different oxides and try them:
try 1,2,3, nickel
and 1,2,3, nickel plus 5 Titanium.
Try to slow cooling, Do you get crystals?
Not sure too much alumina.
I have two other waxy look glazes but they are not in the stable glazes
limits.
J&R are building us new world. The old world still exist. we are more
suspiciouss, carfull but still can use the "old glazes"
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
---------- Original Message ----------
>I tested Richard Behren's Satin Matt Cone 6 glaze and fell in love with
>the
>waxy semi-matte surface. However, it leached badly in a 3-day vinegar
>test.
>So, I set about to make it more durable. Despite my efforts, the
>"improved"
>glaze still leaches almost as badly. Any insight any of you can offer
>would
>be most appreciated.
>The original recipe was:
>Feldspar (I used Custer) 34.9
>Whiting 12.62
>Zinc oxide 25.8
>EPK 4.10
>Silica 22.6
>..5 Cobalt carbonate added
>The chemical formula is:
>Na2O .03
>K2O .08
>MgO .00
>CaO .25
>ZnO .64
>Al2O3 .15
>SiO2 1.6
>P2O5 .00
>TiO2 .00
>Fe2O3 .00
>Al:Si 1:10.92
>My improved recipe is:
>Custer feldspar 25.8
>Whiting 5.2
>Zinc Oxide 18.6
>EPK 9.3
>Silica 26.7
>Ferro Frit 3124
>Cobalt carbonate .5
>With a chemical formula of:
>Na2O .07
>K2O .08
>MgO .00
>CaO .24
>ZnO .61
>Al2O3 .25
>SiO2 2.52
>P2O5 .00
>TiO2 .00
>Fe2O3 .00
>Al:Si 1:10.28
>My strategy was to get it within the limits set out by Ron & John in
>"Mastering Cone 6 Glazes", boost the alumina and silica up into the
>durable
>range, keep the Al:Si ratio near the original values, & keep the fluxes
>near
>their original values.
>The surface quality of the new glaze is very like the original. The
>color
>response is a bit less intense. Once again, it is a thing of beauty,
>but
>not durable. Should I just keep boosting up the Al & Si until I find a
>durable result or ruin the surface quality, whichever comes first?
>Wanda
>________________________________________________________________________
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>melpots@pclink.com.
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