Joan Warren on tue 1 jul 97
Hello Clayarters,
One of our Guild members is having a cracking problem with her slip-cast joins.
She is using a commercial cone 10 porcelain casting slip called White Rose and
uses the same slip , after scoring, to join the sections together. Any
suggestions? Thanks in advance.
Joan Warren.
sent via UUCP from: Raven Net, Salt Spring Island, BC, Canada
Fay & Ralph Loewenthal on wed 2 jul 97
Dear Joan, my wife builds sculptured pots (?) from
casting the pot and a slab containing the figures she
needs to put onto the pot. Once the pot is dry enough to
work with, she cuts the figures out of the slab and sticks
them on with normal water or spit from her mouth, what
ever is handy. These work 99.99% of the time. Hope this
helps Ralph in PE SA
Clay on wed 2 jul 97
use vinegar or patch-a-tach by Duncan
Robert S. Bruch on thu 3 jul 97
I think that you are NOT supposed to use
vinegar on slipcast work because the vinegar
will have the opposite effect of deflocculation
and cause problems with the work.
when I have experienced cracking, it has had to
do with the way I applied the joins, ie not supporting
them in the intitial drying process; or, doinbg it too
dry. If both pieces are evenly thick and dry and the
joins are supoported, cracking shouldn't be a problem.
Slow drying in airsealed bags can help.
--
Bob Bruch rsb8@po.cwru.edu
Deborah Redfern on fri 4 jul 97
Hi
I slip cast with ^6 stoneware and when I have to join parts, I wait until
both pieces are leather hard. Often this means that I will have to cast
one piece sooner than the other, as in the case of a solid handle for a
mug. I score both parts with an pen knife, let a little clear water flow
into the score lines, score again and brush a little more water, avoid getting the piece wet>. The idea is to build up a little local slip.
Then I stick the two parts together and with a fairly dry brush sopping wet> I seal over the join by brushing and melding together the clay
surrounding the join. I support the handle with a bit of sponge until it
is all firm. I hardly ever have a problem with cracking with this method.
Deborah Redfern
redfern.d@thezone.net
John H. Rodgers on fri 4 jul 97
-- [ From: John H. Rodgers * EMC.Ver #2.5.02 ] --
I can't help but laugh at this.
In my shop we seem to have done it wrong - everything wrong. Over the years
we have had more people than I can count stop by to see what we were doing -
we always invite visitors in to see the work in progress - and we have been
told by many, "You can't do that!!!" and we just keep right on doing it. And
these are sometimes people who have been in the business a long time
themselves. We wash slip-cast porcelains with water and a sponge for
cleaning( a real no-no in some quarters) , and we use vinegar and slip for
sealing cracks (heaven forbid). But it works for us. And I intend to keep on
doing what works, whether anyone else does or not.
Robert, you are quite right about other factors being involved. Proper
support, uniform drying, slow drying (as in a plastic bag), etc. are all
crucial to the process. I doubt that any one thing can be singled out over
another in importance. We struggle with these all the time to reduce or
eliminate cracking. We produce hundreds of items a month and trying to keep
the cracking to a minimum is essential. Where we are using hired labor for
production, a cracked piece means lost time in repair or re-casting, thereby
increasing costs. Multiply that times many losses and it adds up in a hurry.
John Rodgers - an Alaska Sourdough being parboiled in the heat/humidity of
The Deep South
-------- REPLY, Original message follows --------
Date: Thursday, 03-Jul-97 09:16 AM
From: Robert S. Bruch \ Internet: (rsb8@po.cwru.edu)
To: CLAYART LIST \ Internet: (clayart@lsv.uky.edu)
Subject: Re: Slip-cast joins cracking
----------------------------Original message----------------------------
I think that you are NOT supposed to use vinegar on slipcast work because
the vinegar will have the opposite effect of deflocculation and cause
problems with the work.
when I have experienced cracking, it has had to do with the way I applied
the joins, ie not supporting them in the intitial drying process; or, doinbg
it too dry. If both pieces are evenly thick and dry and the joins are
supoported, cracking shouldn't be a problem. Slow drying in airsealed bags
can help.
--
Bob Bruch rsb8@po.cwru.edu
-------- REPLY, End of original message --------
Marc Kiessling on tue 15 jul 97
Greetings Deborah:
I was wondering if I could trouble you for your
^6 stoneware slip casting recipe. I have used one
other ^6 recipe but would like to try others. Thanks!!
Regards, Marc
At 11:00 PM 7/4/97 EDT, you wrote:
>----------------------------Original message----------------------------
>Hi
>
>I slip cast with ^6 stoneware and when I have to join parts, I wait until
>both pieces are leather hard. Often this means that I will have to cast
>one piece sooner than the other, as in the case of a solid handle for a
>mug. I score both parts with an pen knife, let a little clear water flow
>into the score lines, score again and brush a little more water, >avoid getting the piece wet>. The idea is to build up a little local slip.
> Then I stick the two parts together and with a fairly dry brush >sopping wet> I seal over the join by brushing and melding together the clay
>surrounding the join. I support the handle with a bit of sponge until it
>is all firm. I hardly ever have a problem with cracking with this method.
>
>
>Deborah Redfern
>redfern.d@thezone.net
>
>
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