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bisqueware crack

updated tue 10 may 05

 

ilene richardson on thu 5 may 05


Beginner's question: If there is a small, thin crack in the bottom of a =
bowl after its been bisqued, a small half circle... can I still glaze =
and fire it or is it the end?

Second question: a small crack where the handle of a mug meets the mug =
at the bottom of the handle... the handle being a sculpted mermaid... =
her tail has a small, thin crack where it was supposed to be fully =
attached to the mug.

Both cracks about 1/2 to 1 inch long.

Just looking for advice,
Ilene R

Peter Cunicelli on fri 6 may 05


Hi Ilene,

I hand build with ^10 porcelain and have had a lot of experience with
cracks and some success at fixing them in the greenware and bisqueware
stages.

I use Apt II for highfire. It's really good. You have to mix it with
bone dry clay. Apt II recommends using powdered bisqueware on bisqued
pieces, but I still use bone dry clay. I use my pin tool and dig the
crack out to make sure that it doesn't continue once bisqued again.
Picture the crack as a 'V'. You want to make sure that the thinnest part
of it is dug out. Then, using the Apt II paste, I press it into the crack
and smooth it. It's a lot like spackling a wall. I let it dry and then
gently sand it down. Finally, if it's a bisqued piece, you need to bisque
it again.

Also it's important to note that if you're fixing a bisque piece, you
should put some of the liquid form of the Apt II on the crack itself.
This will keep the bisqued clay from sucking the liquid out of your paste.

Do not use any water.

The consistency of the paste should be like a thin toothpaste. It will
stiffen a bit, but you can continue to work with it.

It's really important that you use the same clay body for the paste that
the piece is made of. Otherwise, you will see the difference when you
pull it out of the kiln.

There's also a way of fixing the crack with paper clay. Jerry Bennett was
explaining this to a fellow student at the Clay Studio a few years ago,
but I was zoning in and out. Perhaps someone else can recommend that
process to you.

I hope this helps.

Peter (www.petercunicelli.com)






On Thu, 5 May 2005 20:48:18 -0400, ilene richardson
wrote:

>Beginner's question: If there is a small, thin crack in the bottom of a
bowl after its been bisqued, a small half circle... can I still glaze and
fire it or is it the end?
>
>Second question: a small crack where the handle of a mug meets the mug
at the bottom of the handle... the handle being a sculpted mermaid... her
tail has a small, thin crack where it was supposed to be fully attached to
the mug.
>
>Both cracks about 1/2 to 1 inch long.
>
>Just looking for advice,
>Ilene R
>
>__________________________________________________________________________
____
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

Lou Roess on fri 6 may 05


On May 6, 2005, at 2:18 AM, Peter Cunicelli wrote:

> I use my pin tool and dig the
> crack out to make sure that it doesn't continue once bisqued again.

I have heard the recommendation to drill a hole at the end of the crack
to make sure it doesn't extend during firing. Makes sense.
Lou

linda rosen on mon 9 may 05


Ilene
Many on this list will tell you that the best plan would be to start =
again
with a new pot, but I take a slightly different approach with my =
students.
It is true that it is not efficient to spend a lot of time trying to =
rescue
and repair a poor pot. Often you can make another in much less time . =
It is
also true that the important thing is to try to understand what caused =
that
crack ( most likely a lake formed in your bowl while throwing or the =
bottom
was too thin in relation to the walls). However there are lessons to be
learned at every stage of making a piece and good glazing is no small
achievement. Go ahead an glaze that piece. The crack will not dissappear =
and
will likely get worse but you can practice on this one so that when you =
make
a better bowl next time you will be more likely to be happy with your =
glaze
job... The goal is to get control ( well, some, anyway).

May the kiln Gods smile on your work.

Linda


-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of ilene
richardson
Sent: Thursday, May 05, 2005 8:48 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: bisqueware crack


Beginner's question: If there is a small, thin crack in the bottom of a
bowl after its been bisqued, a small half circle... can I still glaze =
and
fire it or is it the end?

Second question: a small crack where the handle of a mug meets the mug =
at
the bottom of the handle... the handle being a sculpted mermaid... her =
tail
has a small, thin crack where it was supposed to be fully attached to =
the
mug.

Both cracks about 1/2 to 1 inch long.

Just looking for advice,
Ilene R

_________________________________________________________________________=
___
__
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.