making plaster molds

I want to experiment a few design ideas, by making molds of body parts -
i.e. hands and feet. Is it possible to make two piece molds, or do they
have to be more complex?

I can't reply to posts for the next two weeks, but I would like some input
and will read on my return.

Many thanks all!

JM

On Fri, 20 May 2005 09:30:02 GMT, "JM" wrote:

I want to experiment a few design ideas, by making molds of body parts -
i.e. hands and feet. Is it possible to make two piece molds, or do they
have to be more complex?


Molds don't have to have more than 2 pieces unless they would have
undercuts that would prevent the clay from coming out. So for example
a hand might be a 2-piece mold, if the hand was open flat and the
parting line was exactly halfway through the thickness of each finger.
But sometimes it is easier to just make a multi-part mold than to try
to figure out how to make a 2-part mold that will work.

Note that plaster releases heat when it sets, so it's not a good idea
to use it directly on skin. You might want to press your hand in a
big slab of clay, make a plaster model from that, and make the
mold from the plaster model. The advantage is that pressing
into soft clay makes it easy to see where the parting line will be.
Soft clay needs no release agent, just pour the plaster over it
directly. Of course, you will need a wall ("cottle") around the slab
to keep the plaster in place. You can make the slab in a plastic
bucket or rectangular freezer container, etc, and no release agent
is needed there either. But you will need release agent between
your plaster model and the plaster mold. Soap is the old standby,
such as Fels Naptha or Ivory made up into a thick solution and
painted on. Don't use liquid dish or hand "soap", since these are
really detergents.

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

Murphys Oil Soap is a good release.


Lee In Mashiko, Japan May 20, 3:21 am show options
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From: "Lee In Mashiko, Japan" - Find messages by
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Date: 20 May 2005 00:21:08 -0700
Local: Fri,May 20 2005 3:21 am
Subject: Rice grains in walls of porcelain bowls
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The ones I have seen have holes all the way through the clay. Glaze
makes a little window in the holes.

--
=E6=9D=8E Lee Love =E5=A4=A7
=E6=84=9B=E3=80=80=E3=80=80 =E3=80=80=E3=80=80 =E9=B1=97
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft

Back from hols now - thanks for the input... I now have a couple of ideas
that i can try.
Thanks again.
JM
"Lee In Mashiko, Japan" wrote in message
oups.com...
Murphys Oil Soap is a good release.


Lee In Mashiko, Japan May 20, 3:21 am show options
Newsgroups: rec.crafts.pottery
From: "Lee In Mashiko, Japan" - Find messages by
this author
Date: 20 May 2005 00:21:08 -0700
Local: Fri,May 20 2005 3:21 am
Subject: Rice grains in walls of porcelain bowls
Reply | Reply to Author | Forward | Print | Individual Message | Show
original | Remove | Report Abuse

The ones I have seen have holes all the way through the clay. Glaze
makes a little window in the holes.

--
? Lee Love ?
??? ?? ?
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft