Ama Menec on tue 27 dec 05
To get the plate to release from the plaster early, dust the plaster mould
with talc first, (use a soft haired Chinese brush to apply it), before you
add the clay. It should part company easier. Also, to stop the distortion of
the rims that leads to warping later, try letting the clay gently fall out
of the mould, by taking the weight of the mould in one hand and a bat in the
other hand, and gently letting the clay fall from the mould to the bat
without exerting any pressure on the clay. Kind of hold them up in a V shape
and rock the clay from one to the other without letting the weight of the
plaster mould press on your clay. You can use a Dremmel to carve a small
handgrip onto the rear of your plate moulds to hold on to.
Ama in Totnes, Devon, UK.
> I am making a series of plates with an intricate design on the rims and
> I am using plaster bats to form the plates. The plates are made upside
> down, and the rim design has been carved into the plaster, so that the
> clay picks up the design as the plate is being formed.
>
> Problem: I am getting rim warpage when the newly formed plate is removed
> from the bat. The plate is allowed to dry to a point, but must be
> removed from the bat before much shrinkage takes place to avoid tearing
> of the pattern in the clay by the plaster bat. The clay has stiffened
> some at this point, but not sufficient to handle. To remove the plate I
> place a piece of gypsum wall board on the bottom of the plate, then flip
> the wallboard, plate,and bat over upside down so as soon as the plaster
> releases the plate, I can lift the bat from the plate and set the plate
> up for further drying. Somewhere at this point I am getting slight
> warpage. By the time the plate is dry it become noticeable. No further
> warpage occurs during firing.
>
> If anyone has any ideas as to how to beter control this warpage I would
> appreciae hearing about it.
>
> Thanks,
>
> John Rodgers
> Chelsea, AL
John Rodgers on tue 10 jan 06
I am making a series of plates with an intricate design on the rims and
I am using plaster bats to form the plates. The plates are made upside
down, and the rim design has been carved into the plaster, so that the
clay picks up the design as the plate is being formed.
Problem: I am getting rim warpage when the newly formed plate is removed
from the bat. The plate is allowed to dry to a point, but must be
removed from the bat before much shrinkage takes place to avoid tearing
of the pattern in the clay by the plaster bat. The clay has stiffened
some at this point, but not sufficient to handle. To remove the plate I
place a piece of gypsum wall board on the bottom of the plate, then flip
the wallboard, plate,and bat over upside down so as soon as the plaster
releases the plate, I can lift the bat from the plate and set the plate
up for further drying. Somewhere at this point I am getting slight
warpage. By the time the plate is dry it become noticeable. No further
warpage occurs during firing.
If anyone has any ideas as to how to beter control this warpage I would
appreciae hearing about it.
Thanks,
John Rodgers
Chelsea, AL
Dave Finkelnburg on tue 10 jan 06
John,
Warpage is usually the result of non-uniform density in the clay. You deform it when it's soft and it opens up a bit, so it shrinks wonky in the firing...doesn't sound like you are doing that, though. In your case, I'd look first to see if there is anything you do in the forming process that makes some parts of the clay more dense than others? Also, is the cross section fairly uniform, allowing for the pattern of course?
Hope you get it sorted out.
Dave Finkelnburg
John Rodgers wrote:
I am making a series of plates with an intricate design on the rims and
I am using plaster bats to form the plates. Problem: I am getting rim warpage when the newly formed plate is removed
from the bat.
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Ruth Ballou on tue 10 jan 06
I would make something to evenly support the rim of the plate as it
is flipped, and for this intermediate drying stage. Suggestions are
a piece of specially cut foam in a circle to support the rim, second
plaster mold made from the outside of the plate, or a bisqued
extruded shape the same diameter as the rim, that conforms to the
negative space under the rim. If the plates are footed, a second
plaster mold could just be of the rim area, or up to the foot. Once
the plate has stiffened enough to handle, then it could be dried in
your usual way. If necessary use wax to keep the rim from drying
faster than the interior of the plate.
Ruth Ballou
Belgium
On Jan 10, 2006, at 8:21 AM, John Rodgers wrote:
> I am making a series of plates with an intricate design on the rims
> and
> I am using plaster bats to form the plates. The plates are made upside
> down, and the rim design has been carved into the plaster, so that the
> clay picks up the design as the plate is being formed.
>
> Problem: I am getting rim warpage when the newly formed plate is
> removed
> from the bat. The plate is allowed to dry to a point, but must be
> removed from the bat before much shrinkage takes place to avoid
> tearing
> of the pattern in the clay by the plaster bat. The clay has stiffened
> some at this point, but not sufficient to handle. To remove the
> plate I
> place a piece of gypsum wall board on the bottom of the plate, then
> flip
> the wallboard, plate,and bat over upside down so as soon as the
> plaster
> releases the plate, I can lift the bat from the plate and set the
> plate
> up for further drying. Somewhere at this point I am getting slight
> warpage. By the time the plate is dry it become noticeable. No further
> warpage occurs during firing.
>
> If anyone has any ideas as to how to beter control this warpage I
> would
> appreciae hearing about it.
>
> Thanks,
>
> John Rodgers
> Chelsea, AL
>
> ______________________________________________________________________
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>
Donald G. Goldsobel on tue 10 jan 06
Subject: Warped Plate Rims
Sometime, when I make thin rimmed bowls, the rim goes out of round/warps. I
take a light bat, larger than the rim and set it on the rim. The bowl rim
goes back into round. I dont know if your rims can support any weight, but
thats the idea if you can use it.
Donald
Craig Clark on tue 10 jan 06
John, one thing that has worked for me is to take the plate and
immediately flip it back over to let it dry on the rim until it is nice
a firm leather. Do the flipping with the same sandwhich technique that
you have described. If have any problem with the flat part of the plate
starting to sag just make up a few thin pieces of material which are the
thickness of the rise of your rim from the top surface of the inside of
you plate. Put the shims on top of the plate before flipping. This will
also help prevent stressing of the rim during drying.
Hope this helps
Craig Dunn CLark
619 East 11 1/2 St.
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
John Rodgers wrote:
> I am making a series of plates with an intricate design on the rims and
> I am using plaster bats to form the plates. The plates are made upside
> down, and the rim design has been carved into the plaster, so that the
> clay picks up the design as the plate is being formed.
>
> Problem: I am getting rim warpage when the newly formed plate is removed
> from the bat. The plate is allowed to dry to a point, but must be
> removed from the bat before much shrinkage takes place to avoid tearing
> of the pattern in the clay by the plaster bat. The clay has stiffened
> some at this point, but not sufficient to handle. To remove the plate I
> place a piece of gypsum wall board on the bottom of the plate, then flip
> the wallboard, plate,and bat over upside down so as soon as the plaster
> releases the plate, I can lift the bat from the plate and set the plate
> up for further drying. Somewhere at this point I am getting slight
> warpage. By the time the plate is dry it become noticeable. No further
> warpage occurs during firing.
>
> If anyone has any ideas as to how to beter control this warpage I would
> appreciae hearing about it.
>
> Thanks,
>
> John Rodgers
> Chelsea, AL
>
> ______________________________________________________________________________
>
> 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.
>
Rose on wed 11 jan 06
I can lift the bat from the plate and set the plate
>up for further drying. Somewhere at this point I am getting slight
>warpage. By the time the plate is dry it become noticeable. No further
>warpage occurs during firing.
>
>If anyone has any ideas as to how to beter control this warpage I would
>appreciae hearing about it.
>
>Thanks,
>
>John Rodgers
>Chelsea, AL
>
John,
You are probably warping the plate when you remove it from the bat. One way
to try to lessen this is to use an air hose to remove the plate from the bat.
You will need to have someone hold the bat upside down and then apply air
pressure from a compressor in between the plate and the bat. The plate should
release and drop onto the bat.
Rose Downs
Terra Madre
www.terramadre.com
Princeton, TX
469-450-5480
Ivor and Olive Lewis on thu 12 jan 06
Dear John Rodgers,=20
You need to have some form of support for the rim of your plate when you =
are removing it from your former.
I suggest you waste a plate by placing a cottle around the former and =
your shaped slab, then casting plaster negative forms of the base of the =
plate. When dry these can be placed over your plates when they are =
inverted, preventing any possibility of gravity distortion.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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