Pamela Jo Stamper on wed 9 sep 98
>----------------------------Original message----------------------------
>I'm looking for a clay body recipe for large slabs - at least an inch
>thick - that will withstand thermal shock, with no cracking, in
>extreme heating and cooling situations. Thanks
Vince Pitelka has a claybody formula called "gods own body" We called it
"gods bod" at Vince's workshop this summer. It might be what you are
looking for.... How about it Vince, will you post "gods bod" for us?
PJo
Vince Pitelka on thu 10 sep 98
>Vince Pitelka has a claybody formula called "gods own body" We called it
>"gods bod" at Vince's workshop this summer. It might be what you are
>looking for.... How about it Vince, will you post "gods bod" for us?
>PJo
There is no mystery to this claybody. It's about as simple as possible -
equal parts by weight goldart, fire clay, ball clay, and extra fine grog.
You can use whatever grade of grog you want. I suppose if you want to
really jack up the thermal-shock resistance you could substitute kyanite
grog. This claybody is extremely refractory, so don't try using it for
functional work at any temperature below ^16..
For my Ancient Clay workshop at Michael McDowell's this past summer the clay
supplier in Tacoma used ultra-fine grog, and the stuff was pretty magical.
When I first handled it I was afraid they had left out the grog altogether.
But it was great to work with, it sanded beautifully, and cooperated
beautifully in speed drying and bonfire firing. This claybody works equally
well for raku, bonfire, and high-fire sculpture. And I never called it
"God's Own Body." Apparently Michael made some such reference when he
ordered the custom blend from Tacoma, and the boxes all came with "God's Own
Body" printed on them. I guess it's appropriate, depending on your own
definitions.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Ron Roy on sat 12 sep 98
Just a note of caution here - if this body is fired above cone 6 there will
be cristobalite formed - which would be exactly the wrong kind of
formulation to use for any clay that had to endure extremes of temperature
after firing.
>----------------------------Original message----------------------------
>There is no mystery to this claybody. It's about as simple as possible -
>equal parts by weight goldart, fire clay, ball clay, and extra fine grog.
>You can use whatever grade of grog you want. I suppose if you want to
>really jack up the thermal-shock resistance you could substitute kyanite
>grog. This claybody is extremely refractory, so don't try using it for
>functional work at any temperature below ^16..
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
Tony Hansen on sun 13 sep 98
I've always thought it was best to avoid clays with high
amounts of free silica for thermal shock bodies (i.e.
ball clay, fireclay). Do you have any theories why your
recipe works well?
I'm wondering whether the best thermal shock bodies would
not have a high amount of thermally stable minerals (i.e.
pyrax, kyanite, wollastonite) with no-silica grog and
kaolin/bentonite for plasticity.
--
T o n y H a n s e n thansen@digitalfire.com
Don't fight the dragon alone http://digitalfire.com
Calculation/Database Software for Ceramic Industry
Vince Pitelka on mon 14 sep 98
At 08:21 PM 9/13/98 -0400, you wrote:
>----------------------------Original message----------------------------
>I've always thought it was best to avoid clays with high
>amounts of free silica for thermal shock bodies (i.e.
>ball clay, fireclay). Do you have any theories why your
>recipe works well?
Hey, come on Tony, you're the clay wizard here. I have always been guilty
of drawing conclusions based upon what happens in the kiln, the bonfire, and
the oven rather than what looks right on paper. This claybody never really
vitrifies even at high-temperature, and at bonfire and raku temperatures it
is extremely porous, although fairly strong as well. My claims for thermal
shock resistance in the "God's Own" claybody only extended to its tendency
to come out of the bonfiring and raku firing intact. I never meant to imply
that it would be appropriate as a thermal shock body in the kitchen. When
we do bonfirings with this claybody, I get 100% success, unless something
cracks from getting hit by a stick of wood, etc. So it is certainly thermal
shock resistant in that situation.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
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