Vince Pitelka on sat 6 nov 99
>Are you sure about that? Hamer charts the shrinkage of a ball clay, a
>refractory red clay, and a prepared earthenware body. The ball clay has
>very little shrinkage between bone-dry and bisque, but the other two bodies
>show a substantial degree of shrinkage in that stage.
Ray -
I acknowledge the Hamers as experts on most things ceramic, but in my
experience no claybody I have used has ever showed any perceptible shrinkage
from bone-dry to bisque-fired. This includes stoneware, porcelain,
whiteware, and terracotta.
Best wishes -
- Vince
Vince Pitelka
Home - vpitelka@DeKalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Louis H.. Katz on sun 7 nov 99
Depends what you define as bisque. Redart based earthenwares start to tighten
up around 05 04 and probably show some shrinkage.
On the other note all of the tests that I have ever run showed less than 1%
shrinkage between bonedry and 08 bisque.
If this thread started in response to cracking, I would suggest that cracks
cooling bisque are definately possible particularly with wide ware.
Louis
Vince Pitelka wrote:
> ----------------------------Original message----------------------------
> >Are you sure about that? Hamer charts the shrinkage of a ball clay, a
> >refractory red clay, and a prepared earthenware body. The ball clay has
> >very little shrinkage between bone-dry and bisque, but the other two bodies
> >show a substantial degree of shrinkage in that stage.
>
> Ray -
> I acknowledge the Hamers as experts on most things ceramic, but in my
> experience no claybody I have used has ever showed any perceptible shrinkage
> from bone-dry to bisque-fired. This includes stoneware, porcelain,
> whiteware, and terracotta.
> Best wishes -
> - Vince
>
> Vince Pitelka
> Home - vpitelka@DeKalb.net
> 615/597-5376
> Work - wpitelka@tntech.edu
> 615/597-6801 ext. 111, fax 615/597-6803
> Appalachian Center for Crafts
> Tennessee Technological University
> 1560 Craft Center Drive, Smithville TN 37166
Ron Roy on sun 7 nov 99
I actually id an experiment on this once - Rhodes says little and Nelson
said lots but the bisque pots were still touching after the bisque.
Made some bars out of my cone 10 body and took them out of the kiln every
100 degrees after 500 degrees - a very small amount of shrink at cone 04 -
this would be different if a low fired body were somewhat vitrified - by
using frit for instance. The fired shrinkage is tied to vitrification and
any any memory left in the clay from forming - like a thrown spout twisting
even though it was cut straight when bone dry.
It is likley that Hamer is correct because a stoneware clay does not
vitrify much at bisque but if the low fired bodies were fluxed then they
will get smaller at biqsues temps - if high enough.
RR
>----------------------------Original message----------------------------
>>Are you sure about that? Hamer charts the shrinkage of a ball clay, a
>>refractory red clay, and a prepared earthenware body. The ball clay has
>>very little shrinkage between bone-dry and bisque, but the other two bodies
>>show a substantial degree of shrinkage in that stage.
>
>Ray -
>I acknowledge the Hamers as experts on most things ceramic, but in my
>experience no claybody I have used has ever showed any perceptible shrinkage
>from bone-dry to bisque-fired. This includes stoneware, porcelain,
>whiteware, and terracotta.
>Best wishes -
>- Vince
>
>Vince Pitelka
>Home - vpitelka@DeKalb.net
>615/597-5376
>Work - wpitelka@tntech.edu
>615/597-6801 ext. 111, fax 615/597-6803
>Appalachian Center for Crafts
>Tennessee Technological University
>1560 Craft Center Drive, Smithville TN 37166
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Ray Aldridge on mon 8 nov 99
At 05:31 PM 11/7/99 EST, you wrote:
>----------------------------Original message----------------------------
>I actually id an experiment on this once - Rhodes says little and Nelson
>said lots but the bisque pots were still touching after the bisque.
>
You're braver than me. With certain forms, such as large extended bowls,
I'm always afraid to bisque them touching, because I worry that heat
expansion at a vulnerable point would push them together and cause a stress
crack.
Ray
Aldridge Porcelain and Stoneware
http://www.goodpots.com
amy parker on tue 9 nov 99
I'da sworn that Vince was nuts. BUT - I went and retrieved my "ruler" made
from Kickwheel GA Peach clay, marked at wet stage with a needle tool, and at
bone dry with velvet underglaze, and by golly, fired to bisque 06, there is
indeed absolutely no shrinkage from the bone to the bisque! Hmmm...this
could be terribly useful knowledge if one has lost a lid at the bisque
stage!!! I'll have to make a "ruler" for the porcelain clay now!
Amy
>Ray -
>I acknowledge the Hamers as experts on most things ceramic, but in my
>experience no claybody I have used has ever showed any perceptible shrinkage
>from bone-dry to bisque-fired. This includes stoneware, porcelain,
>whiteware, and terracotta.
>Best wishes -
>- Vince
amy parker Lithonia, GA
amyp@sd-software.com
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