Brenda Woods on sun 29 nov 98
Dear Friends,
I have a question for you. I have made two pickle crocks and both have
cracked in the bottom. The first cracked after the bisque firing and then
worse after the cone 9 firing. I threw the bottom of this crock on the
wheel and then I added a coiled body approx. 22" high.
The second one I coiled the bottom and the body and it has cracked before
it was leather hard. I have been very patient while making and drying both
of these crocks. I have scored and moistened these crocks to the point of
obsessiveness, and the darn things keep cracking on the bottom. Please help
me with any suggestions that you may have.
Thank you,
Brenda Woods
Louis on mon 30 nov 98
Hi Brenda,
As sson as you can safely turn the crocks upside down do so. Tap the center of
the bottom in a little ways so it is curved. The theories concerning the need
for a curve are:
1. Curved surfaces put under tension in thier centers will flatten relieving
any stress.
2. Curved planes are inherently stronger.
Louis Katz
Brenda Woods wrote:
> ----------------------------Original message----------------------------
> Dear Friends,
>
> I have a question for you. I have made two pickle crocks and both have
> cracked in the bottom. The first cracked after the bisque firing and then
>
Thonas C. Curran on mon 30 nov 98
Brenda Woods wrote:
>
> ----------------------------Original message----------------------------
> Dear Friends,
>
> I have a question for you. I have made two pickle crocks and both have
> cracked in the bottom. The first cracked after the bisque firing and then
> worse after the cone 9 firing. I threw the bottom of this crock on the
> wheel and then I added a coiled body approx. 22" high.
> The second one I coiled the bottom and the body and it has cracked before
> it was leather hard. I have been very patient while making and drying both
> of these crocks. I have scored and moistened these crocks to the point of
> obsessiveness, and the darn things keep cracking on the bottom. Please help
> me with any suggestions that you may have.
>
> Thank you,
>
> Brenda Woods
Hi...take a peek at Hamer's POTTER'S DICTIONARY OF MATERIALS AND
TECHNIQUES. There are about 9 pages of different cracks and reasons for
cracking. (I can't believe my edition was copyrighted in '75. Perhaps
there is new edition. At any rate, cracks are still cracks.) Good luck
with the next pickle crocks.! Carolyn N. Curran aka cnc
Laurie and Dan Hennig on tue 1 dec 98
Try using a rib to compress the bottom of the pot while throwing. Also
when the pot is leather hard turn it over and tap the center of the pot and
then run your finger around the bottom of the pot about an inch from the
outside edge.
Judith Musicant on wed 2 dec 98
Brenda,
I recently posted this suggestion for avoiding cracked bottoms, but here
goes again. Try placing your wedged clay on the wheel with the sideof the
wedge down on the wheelhead, rather than with the base of the wedge down,
or the point of the wedge down. Or, if you're using pugged clay, place the
pugged piece on its side as well. There is a scientific explanation for
why this works, having to do with the direction of the clay particles after
a piece of clay is wedged or pugged. Perhaps one of our more technically
oriented colleagues might explain it further. Since first trying this
technique, about 10 pots ago, I've not had one crack. Before that, even
the bases of mugs were cracking on me. Needless to say, I'm thrilled with
this simple technique. Brenda, if you try it, please keep us posted about
whether it works for you. (I've had a couple of private success story
posts since my last message on this.) Cracking seems to be a pretty
universal problem.
Judy
Joy Holdread on wed 2 dec 98
In a message dated 11/29/98 5:49:58 PM US Mountain Standard Time,
brendaw@CLDS.NET writes:
>
> I have a question for you. I have made two pickle crocks and both have
> cracked in the bottom. The first cracked after the bisque firing and then
> worse after the cone 9 firing. I threw the bottom of this crock on the
> wheel and then I added a coiled body approx. 22" high.
> The second one I coiled the bottom and the body and it has cracked before
> it was leather hard. I have been very patient while making and drying both
> of these crocks. I have scored and moistened these crocks to the point of
> obsessiveness, and the darn things keep cracking on the bottom. Please
help
> me with any suggestions that you may have.
>
> Thank you,
>
> Brenda Woods
>
Has this clay behaved well with other works? The bottom will dry slower that
the sides, consider covering lightly, dry on something that gives, newspaper
or a bed of powdered ground clay.
Joy in Tucson
Brenda Woods on thu 3 dec 98
Thanks Judy!!
I will keep you posted on my progress. I plan to be starting a new crock
any day. It is the end of the semester at school and I am trying to get
several things done right now but I do plan to try this ASAP.
Brenda :)
----------
>From: Judith Musicant
>To: CLAYART@LSV.UKY.EDU
>Subject: Cracking Crocks
>Date: Wed, Dec 2, 1998, 11:06 AM
>
>----------------------------Original message----------------------------
>
>
>Brenda,
>
>I recently posted this suggestion for avoiding cracked bottoms, but here
>goes again. Try placing your wedged clay on the wheel with the side of the
>wedge down on the wheelhead, rather than with the base of the wedge down,
>or the point of the wedge down. Or, if you're using pugged clay, place the
>pugged piece on its side as well. There is a scientific explanation for
>why this works, having to do with the direction of the clay particles after
>a piece of clay is wedged or pugged. Perhaps one of our more technically
>oriented colleagues might explain it further. Since first trying this
>technique, about 10 pots ago, I've not had one crack. Before that, even
>the bases of mugs were cracking on me. Needless to say, I'm thrilled with
>this simple technique. Brenda, if you try it, please keep us posted about
>whether it works for you. (I've had a couple of private success story
>posts since my last message on this.) Cracking seems to be a pretty
>universal problem.
>
>Judy
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