Russell L. Block on mon 19 apr 99
My first instructor said that if a pot cracks, toss it. However, as I
spend more time on them this is becoming harder to do. If you have a pot
you can't bear to toss, is there something that will fill in the cracks on
a bisque piece? What about a glazed piece; I glaze at cone 5?
Sue&Jon on tue 20 apr 99
Russell, I wait until they are completely finished then fill the crack with PC-7
construction epoxy. It's charcoal grey in color and accepts paint well. I
don't know about food safety because I've only done this to birdbaths. There
has also been a discussion on clayart about colored epoxies. I bet those would
work equally well and look better. When I sell pieces with cracks that have
been filled, I make mention of it on the hang tag and point it out to the
customer. However, I usually don't discount the price because of it, since I am
able to repair almost invisibly. (My surfaces are very busy and the PC-7 can be
sculpted to match, using a wet tool.)
As far as repairing in the bisque state, I have done this using a mixture of
powdered bisque clay (ground in a coffee bean grinder) and Ceramic Enhancer,
which I get from Continental clay in Minneapolis. However, I only have about a
20% success rate with this, as the cracks tend to reappear (albeit smaller).
Sue Christensen
----------------------------Original message----------------------------
My first instructor said that if a pot cracks, toss it. However, as I
spend more time on them this is becoming harder to do. If you have a pot
you can't bear to toss, is there something that will fill in the cracks on
a bisque piece? What about a glazed piece; I glaze at cone 5?
************************************************
Sue Christensen and/or Jon Simpson
Nameless Wildness
Minneapolis, Minnesota
************************************************
Autumn Downey on tue 20 apr 99
This "fix" came from Clayart a couple of years ago, and I can't find the
original posting to credit it, but I have used the hint a few times and it
has worked quite well.
Take a little of the glaze that you intend glaze the pot with. Mix talc
into it until it is quite stiff - (about like what you'd use for polyfilla.)
Fill the crack with this mixture and then glaze. I have done this on bisque
pots and also refired glazed pots with this fix. (Firings are cone 5-6).
I was using a white clay and white glaze - it could be that these were
especially compatible materials, but one disastrous looking teapot spout
that was coming away from the pot healed up perfectly.
Autumn Downey
At 10:43 AM 1999-04-19 EDT, you wrote:
>----------------------------Original message----------------------------
>My first instructor said that if a pot cracks, toss it. However, as I
>spend more time on them this is becoming harder to do. If you have a pot
>you can't bear to toss, is there something that will fill in the cracks on
>a bisque piece? What about a glazed piece; I glaze at cone 5?
>
>
Frank Cormier on tue 20 apr 99
In a message dated 4/19/99 10:45:35 AM Eastern Daylight Time,
rblock@mail.sdsu.edu writes:
<< ---------------------------Original message----------------------------
My first instructor said that if a pot cracks, toss it. However, as I
spend more time on them this is becoming harder to do. If you have a pot
you can't bear to toss, is there something that will fill in the cracks on
a bisque piece? What about a glazed piece; I glaze at cone 5?
>>
Russell,
Could you be more specific on the types of cracks and where they are. What
I would do is focus on what is causing the cracks. Correcting the causes to
me would be a better solution for the problems that you are having.
Frank Cormier
Cormier Pottery LLC.
http://www.cormierpottery.com
-------------
Mike Gordon on tue 20 apr 99
Russel,
I have taken some DRY glaze of the type you are using and mixed maybe a
third silica in with it and then added water to make a thick paste and
rubbed it into the crack. I then glazed over it . Mike
Dale A. Neese on tue 20 apr 99
If you are able throw a lot, toss it. You can make another one faster than
spend all the time on a cracked one. But if you must keep it for yourself,
then mix up some clay with some paper, toilet paper works great, and push it
into the cracks of your bisque piece. Dry, then glaze. This might not work
on all cracks, but just experimenting with a batch I made, it works fairly
well. You might want to look at earlier messages about "paper clay".
-----Original Message-----
From: Russell L. Block
To: CLAYART@LSV.UKY.EDU
Date: Monday, April 19, 1999 9:46 AM
Subject: cracks and favorite pots
----------------------------Original message----------------------------
My first instructor said that if a pot cracks, toss it. However, as I
spend more time on them this is becoming harder to do. If you have a pot
you can't bear to toss, is there something that will fill in the cracks on
a bisque piece? What about a glazed piece; I glaze at cone 5?
Fredrick Paget on thu 22 apr 99
Many years ago, in the fifties in fact, I was a sort of universal expert
in "Potting" at our factory. Yes, that is what it is called - putting a
transformer in a metal box and filling it with epoxy is potting. There is a
lot of art and technology in this if you want the product to pass the tests
in a Military Specification. Anyway since we were a big firm and good
customer the raw material suppliers would give us free samples of just
about anything.
I got a sample kit from Ferro that had about 10 quarter pound cans of
epoxy colors in every color of the rainbow. This is the same company that
makes frits but they are much bigger in plastics. These colors are very
strong and are pigments ground in some sort of medium that is compatible
with epoxy resin.
They keep forever (I still have some and they are still good). They can be
mixed into a clear epoxy that has been mixed with the correct amount of
hardener and if the percentage is not too high the resin sets up in the
usual manner. We used to get resin in 50 gallon drums from suppliers like
Shell, Ciba, or Dow.
A good mix for art repair would be:
Shell Epon 828 100
Shell curing Agent U 28
Silica 325 Mesh enough to make a paste
Cabosil (fume silica) enough to make the paste thixotropic ( a couple of
percent) Get this from a boat supplier.
Ferro color as required ( a few percent)
.
This will cure at room temperature but is improved by a warm baking at 140
deg. F. It has a pot life of around 20 minutes. It generates heat - depends
on temperature and volume in the mixing pot. Spread it out thin in a flat
plate so the heat can escape to extend pot life.
Like most epoxys this is a possible allergic agent and the curing agent is
an irritant. Wear gloves.
The West resin and hardener sold in boat shops can be used as a base
instead of the Shell. (They get it from Ciba or somewhat) They may have
colors too.
You can mix any inert powder into the base to get different effects.
Kaolin, whiting, sawdust, mica, titania, powered metals, fiber, you name
it, all have been used.
Have fun,
Fred Paget
> Re: cracks and favorite pots
>
>----------------------------Original message----------------------------
>Russell, I wait until they are completely finished then fill the crack
>with PC-7
>construction epoxy. It's charcoal grey in color and accepts paint well. I
>don't know about food safety because I've only done this to birdbaths. There
>has also been a discussion on clayart about colored epoxies. I bet those
>would
>work equally well and look better. When I sell pieces with cracks that have
>been filled, I make mention of it on the hang tag and point it out to the
>customer. However, I usually don't discount the price because of it,
>since I am
>able to repair almost invisibly. (My surfaces are very busy and the PC-7
>can be
>sculpted to match, using a wet tool.)
.....).
>
>Sue Christensen
>
>----------------------------Original message----------------------------
>>My first instructor said that if a pot cracks, toss it. However, as I
>>spend more time on them this is becoming harder to do. If you have a pot
>>you can't bear to toss, is there something that will fill in the cracks on
>>a bisque piece? What about a glazed piece; I glaze at cone 5?
-
From Fred Paget, in marvelous Marin County, California, USA
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