Joy Holdread on sat 6 mar 99
I'm pressing large slabs onto a plaster molds with an irregular surface. My
first 2 cracked while drying. I'm considering paper clay. Has anyone tried
large platters of paper clay either rolled out like regular clay or brushed
on? Any advise. Meanwhile I'm considering a wider foot, letting it stiffen up
more before I flip it, adding grog to the clay. Any other ideas?
Joy
Marty Anderson on sun 7 mar 99
Hi Joy,
You stated you are pressing your slabs onto a mold, so I am assuming it is a
hump mold. You may be letting it get to dry on the mold causing stress from
the shrinkage. Also, how big is the platter? I had build large platters
from a mold I made last year. The finished platter is 26 1/2" Long x 16
1/2" wide x 3" high. My mold is a slump mold with each side concave which
allows the platter to be build oval, or be altered in different shapes on
all sides. I cover it with plastic and let it stay in the mold for about a
week. ( I live in Dallas so the humidity is not dry) I uncover it
periodically for short periods of time. When it reaches a strong enough
leather hard stage I fill the cavity with plastic, towels, bubble wrap,
whatever and my husband helps me flip it. I then add the foot which is
leather hard but probably not as leather hard as the platter. I fire to
cone 6. It fired great, no warps. My slab was also approx 1/2" thick to
start. I have never tried the paper clay. The clay I use is a grogless
stoneware. I have had the same problem with cracked platters only with
having used hump molds and letting them dry too much before removing. I
lost 7 out of 8 before I realized what was happening. Don't know if this
help you.
marty
martya@airmail.net
-----Original Message-----
From: Joy Holdread
To: CLAYART@LSV.UKY.EDU
Date: Saturday, March 06, 1999 6:31 PM
Subject: Cracking large hand built platters.
>----------------------------Original message----------------------------
>I'm pressing large slabs onto a plaster molds with an irregular surface.
My
>first 2 cracked while drying. I'm considering paper clay. Has anyone
tried
>large platters of paper clay either rolled out like regular clay or brushed
>on? Any advise. Meanwhile I'm considering a wider foot, letting it stiffen
up
>more before I flip it, adding grog to the clay. Any other ideas?
>Joy
>
Bill Williams on sun 7 mar 99
I used to do pour my own porcelain dolls, so I know a little about the
drying factor. You may need a good mold release. Also, if you leave your
piece in the mold to dry completely, it will crack. You have to get the
piece out of the mold as soon as you can do so without harming it. The
plaster drinks up all the liquid in the clay rather quickly and it would be
even faster if you use clay instead of slip. When the water is gone, the
piece will start to shrink and it will crack because shrinkage is impossible
inside the mold. Hope this helps. Connie
-----Original Message-----
From: Joy Holdread
To: CLAYART@LSV.UKY.EDU
Date: Saturday, March 06, 1999 8:31 PM
Subject: Cracking large hand built platters.
>----------------------------Original message----------------------------
>I'm pressing large slabs onto a plaster molds with an irregular surface.
My
>first 2 cracked while drying. I'm considering paper clay. Has anyone
tried
>large platters of paper clay either rolled out like regular clay or brushed
>on? Any advise. Meanwhile I'm considering a wider foot, letting it stiffen
up
>more before I flip it, adding grog to the clay. Any other ideas?
>Joy
>
Linda Blossom on sun 7 mar 99
"Dear Joy,
It sounds like you are using a throwing clay for large slab work. I realize
that it happens all the time and many will claim it works for them. I use a
highly grogged clay (20-25% fine grog) and 30% by volume paper pulp. It
rarely has warping problems and I never have a cracking problem. This clay
is, in my mind, a slab clay which I use for thick architectural pieces,
tiles, and flat, slab style plates. It would probably be a nightmare for
someone throwing but then it is not a throwing clay. I could call it a tile
clay or an architectural clay, but I think slab covers it.
Linda Blossom
2366 Slaterville Rd
Ithaca, NY 14850
607-539-7912
blossom@twcny.rr.com
-----Original Message-----
From: Joy Holdread
To: CLAYART@LSV.UKY.EDU
Date: Saturday, March 06, 1999 9:28 PM
Subject: Cracking large hand built platters.
>----------------------------Original message----------------------------
>I'm pressing large slabs onto a plaster molds with an irregular surface.
My
>first 2 cracked while drying. I'm considering paper clay. Has anyone
tried
>large platters of paper clay either rolled out like regular clay or brushed
>on? Any advise. Meanwhile I'm considering a wider foot, letting it stiffen
up
>more before I flip it, adding grog to the clay. Any other ideas?
>Joy
>
eden@sover.net on sun 7 mar 99
I am having such unqualified success with my "paperclay" doing slab-rolled
work that I wouldn't consider doing this job of yours any other way. I
would like to re-mention that my "paperclay" is actually
"wood-powder-clay", made from smooth-mixed scrap slop mixed with 1/2 to 2/3
its volume with fine wood powder that comes out of the wood grinders at a
local woodworking shop. I found with paper-pulp clay that cutting slabs
was a real trial, that problem is resolved with this method. Another point
is that I paint the surface with afew coats of clay slip so that the
surface is still a fine smooth surface for decoration.
However you are making your paperclay please do give it a try for this
project before bothering with other solutions.
Eleanora
At 09:30 PM 3/6/99 -0500, you wrote:
>----------------------------Original message----------------------------
>I'm pressing large slabs onto a plaster molds with an irregular surface. My
>first 2 cracked while drying. I'm considering paper clay. Has anyone tried
>large platters of paper clay either rolled out like regular clay or brushed
>on? Any advise. Meanwhile I'm considering a wider foot, letting it
stiffen up
>more before I flip it, adding grog to the clay. Any other ideas?
>Joy
>
Eleanora Eden 802 869-2003
Paradise Hill
Bellows Falls, VT 05101 eden@sover.net
Smulders on mon 8 mar 99
Joy:
We produce a large quantity of press mold platters. The large oval size( slump)
had the same problem with cracking till a started using paper clay and making th
a bit thicker.
I bisque them to o4 very very slowly and can stack them only two high. They cam
out beautifully with practically no cracking.
Good Luck!
Evonne Smulders
Black Diamond Alberta
Joy Holdread wrote:
> ----------------------------Original message----------------------------
> I'm pressing large slabs onto a plaster molds with an irregular surface. My
> first 2 cracked while drying. I'm considering paper clay. Has anyone tried
> large platters of paper clay either rolled out like regular clay or brushed
> on? Any advise. Meanwhile I'm considering a wider foot, letting it stiffen up
> more before I flip it, adding grog to the clay. Any other ideas?
> Joy
ELIZABETH JACOBS on sun 14 mar 99
Joy... I dry my students slumped platters between two pieces of sheetrock boa
as soon as they are stiff enough to support the wieght. This helps it dry evenly
maintain a flat bottom, and keep the rim from warping.
Joy Holdread wrote:
> ----------------------------Original message----------------------------
> I'm pressing large slabs onto a plaster molds with an irregular surface. My
> first 2 cracked while drying. I'm considering paper clay. Has anyone tried
> large platters of paper clay either rolled out like regular clay or brushed
> on? Any advise. Meanwhile I'm considering a wider foot, letting it stiffen up
> more before I flip it, adding grog to the clay. Any other ideas?
> Joy
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