Greg Skwira on sat 6 nov 99
A crazing question:
After liking the test tile results of the Phoenix 2 glaze in Richard Zakin's E
lectric Kiln Ceramics, I mixed up a batch and took the first few pots out of
the kiln yesterday. Two different bodies were fired to Cone 6 -- one of them
Minnesota Clay white stoneware and one of them a white stoneware from a
communal studio where I throw. The communal body is fine, but the Minnesota
is crazing. I'm wondering if I can tinker with the glaze recipe to make it
work on the Minnesota clay without changing the glaze's appearance and
excellent performance on the other body -- either by adding some silica (5%?)
to the glaze or reducing the soda feldspar. Glaze recipe is
F-4 soda feldspar 30
ball clay 20
Barnard clay 20
Gerstley borate 30
Would appreciate any thoughts.
--Greg Skwira, Michigan
Ron Roy on sun 7 nov 99
Hi Greg,
I have reduced the expansion/contraction a bit - you will just have to try
it. If you just add silica the glaze will just get shinier. Barnard has
some MnO2 - just so you know about that. I would be better if I knew which
ball clay you are using.
I have to assume this is a cone 6 glaze - right?
F-4 soda feldspar 27.0
ball clay 22.0
Barnard clay 20.0
Talc 3.0
Gerstley borate 28.0
Total 100.0
When a glaze works on one clay and you lower the expansion so it won't
craze on another body - you may find the glaze will shiver or dunt
(expansion of glaze too low) on the other body - so test for that.
RR
>----------------------------Original message----------------------------
>A crazing question:
>
>After liking the test tile results of the Phoenix 2 glaze in Richard Zakin's E
>lectric Kiln Ceramics, I mixed up a batch and took the first few pots out of
>the kiln yesterday. Two different bodies were fired to Cone 6 -- one of them
>Minnesota Clay white stoneware and one of them a white stoneware from a
>communal studio where I throw. The communal body is fine, but the Minnesota
>is crazing. I'm wondering if I can tinker with the glaze recipe to make it
>work on the Minnesota clay without changing the glaze's appearance and
>excellent performance on the other body -- either by adding some silica (5%?)
>to the glaze or reducing the soda feldspar. Glaze recipe is
>
>F-4 soda feldspar 30
>ball clay 20
>Barnard clay 20
>Gerstley borate 30
>
>Would appreciate any thoughts.
>
>--Greg Skwira, Michigan
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Paul Taylor on tue 9 nov 99
Dear Greg
M y first action would be to change the ballclay to a more siliceous type
if that is possible.
If that did not work; Then I would add the quarts, or substitute some of the
soda feldspar with potash feldspar or Cornish stone but I suspect this may
change the other qualities of the glaze. I think this glaze will take a lot
of changes to its percentages so adding five percent quarts should also
work.
Paul
----------
>From: Greg Skwira
>To: CLAYART@LSV.UKY.EDU
>Subject: Faltering Phoenix
>Date: Sun, Nov 7, 1999, 1:42 am
>
>----------------------------Original message----------------------------
>A crazing question:
>
>After liking the test tile results of the Phoenix 2 glaze in Richard Zakin's E
>lectric Kiln Ceramics, I mixed up a batch and took the first few pots out of
>the kiln yesterday. Two different bodies were fired to Cone 6 -- one of them
>Minnesota Clay white stoneware and one of them a white stoneware from a
>communal studio where I throw. The communal body is fine, but the Minnesota
>is crazing. I'm wondering if I can tinker with the glaze recipe to make it
>work on the Minnesota clay without changing the glaze's appearance and
>excellent performance on the other body -- either by adding some silica (5%?)
>to the glaze or reducing the soda feldspar. Glaze recipe is
>
>F-4 soda feldspar 30
>ball clay 20
>Barnard clay 20
>Gerstley borate 30
>
>Would appreciate any thoughts.
>
>--Greg Skwira, Michigan
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