Leslie Ihde on sun 21 jul 96
Dear Clayarters,
I recently began using some plaster molds to make platters
and bowls on
the wheel with the "pure and simple" forms. I think I should be doing
something different. I would have thought that the platter would dry off
the mold in a couple days. The first wone seemed firmer than leather hard
and I couldn't get the damn thing off the plaster mold and it finally
cracked. The second one did better- came off the encouragement after 2
days, and was quite firm. I would have liked it to be a bit softer so
that I could add some clay pieces to the inside of the platter when it
came off the plaster bat. Should I be trying to get these things off
after a couple of hours?
Thanks for your generous help,
Leslie
Vestal, NY
Jonathan Kaplan on mon 22 jul 96
>----------------------------Original message----------------------------
>Dear Clayarters,
>I recently began using some plaster molds to make platters
>and bowls on
>the wheel with the "pure and simple" forms. I think I should be doing
>something different. I would have thought that the platter would dry off
>the mold in a couple days. The first wone seemed firmer than leather hard
>and I couldn't get the damn thing off the plaster mold and it finally
>cracked. The second one did better- came off the encouragement after 2
>days, and was quite firm. I would have liked it to be a bit softer so
>that I could add some clay pieces to the inside of the platter when it
>came off the plaster bat. Should I be trying to get these things off
>after a couple of hours?
>Thanks for your generous help,
>Leslie
>Vestal, NY
Leslie: The plaster needs to cure so that the water of crystalization, when
the plaster was mixed and poured, has time to evaporate from the finished
mold. The pure and simple molds look to me as if they have adequate draft
to release a simple form, so that should not be the problem.
Depending on the size of the piece, you should be able to put these puppies
off with more than enough time to add clay, etc. For example,I make fairly
large platters, 25" wet. from a rolled slab. I cut them in a large disk,
slump them over the mold (a large plaster hump made from a kids sledding
dtray), throw them down and compress the entire piece. Then throw the foot.
The come off the hump mold after sitting over night to stiffen up, and I
can still trim or alter them.
It is important that no water gets between the cpay surface and the surface
of the plaster mold.
Does this help?
Jonathan
Jonathan Kaplan
Ceramic Design GroupLtd./Production Services
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139 voice and fax
call before faxing
"Show up, pay attention, tell the truth, don't be attatched to the results!"
Clayton Bailey on mon 22 jul 96
>----------------------------Original message----------------------------
>Dear Clayarters,
>I recently began using some plaster molds to make platters
>and bowls on
> I would have thought that the platter would dry off
>the mold in a couple days.
Leslie,,
Make a dust bag out of the foot of an old panty hose. fill it with clay
powder or talc, and dust the mold before you put the slab on. Your platter
will come right off the mold without sticking. CB
Dennis Whitfield on mon 22 jul 96
>----------------------------Original message----------------------------
>Dear Clayarters,
>I recently began using some plaster molds to make platters
>and bowls on
>the wheel with the "pure and simple" forms. I think I should be doing
>something different. I would have thought that the platter would dry off
>the mold in a couple days. The first wone seemed firmer than leather hard
>and I couldn't get the damn thing off the plaster mold and it finally
>cracked. The second one did better- came off the encouragement after 2
>days, and was quite firm. I would have liked it to be a bit softer so
>that I could add some clay pieces to the inside of the platter when it
>came off the plaster bat. Should I be trying to get these things off
>after a couple of hours?
>Thanks for your generous help,
>Leslie
>Vestal, NY
>
>
Leslie,
Let your moulds dry out - this may take a week or more following pouring.
Lift the leather hard work off the mould by blowing air form a compressed
air gun in at the rim of the platter or drill a small hole through the mould
and blow air through the hole.
Denis
****************************************************************************
DR DENIS WHITFIELD
Senior Lecturer
Co Director, Centre for Ceramic Research, Design and Production
Department of Visual and Peforming Arts
University of Western Sydney, Macarthur
PO Box 555
CAMPBELLTOWN NSW 2560
AUSTRALIA
email: d.whitfield@uws.edu.au
phone: 02 7729345
****************************************************************************
Syrylyn on mon 22 jul 96
I want to make plaster press molds for my necklace medallions. Now should I
make a plaster mold off of freshly made clay piece, or can I used a bisqued
piece? What can I use as a release agent if I do it off a bisqued piece?
My reason for wanting to do it off of a bisqued piece is to reduce it in
size by firing it.
Any advice is appreciated.
Thanks, Syrylyn
----------------------------------------------------------------------------
---------------
**Syrylyn Rainbowdragon** smeadors@indy.net
******* MAGIC HAPPENS******* ;-)
_____________________________________________________________
SANTERRE ROBERT on tue 23 jul 96
Syrylyn,
I've used either leather hard clay forms or bisqued pieces (and an endless
variety of other non-clay objects) to make plaster molds. Both work fine.
Obviously the leather hard clay will be less durable and probably good for
only one impression. The best releasing agent I've found is a product
called Armorall (This is a silicone-based spray used in the auto industry
to clean and condition vinyl and leather upholstery. Sold in most US retail
stores with an automotive products section. I have no financial interest in
the company.) Many other agents can be used (liquid soap, Pam, etc.) , but
they all seem to present various problems (messy clean-up, lines in the plaster
mold, etc.)
Bob
santerre_robert@lilly.com
>----------------------------Original message----------------------------
>I want to make plaster press molds for my necklace medallions. Now should I
>make a plaster mold off of freshly made clay piece, or can I used a bisqued
>piece? What can I use as a release agent if I do it off a bisqued piece?
>My reason for wanting to do it off of a bisqued piece is to reduce it in
>size by firing it.
>Any advice is appreciated.
>Thanks, Syrylyn
>----------------------------------------------------------------------------
> **Syrylyn Rainbowdragon** smeadors@indy.net
> ******* MAGIC HAPPENS******* ;-)
PurpleLama@aol.com on mon 24 nov 97
I was inspired as the result of a workshop with Carol Grant at Baltimore
Clayworks. The workshop included making plaster molds.
This weekend my 10 year old nephew visited me. Thinking that I would start
out gently, I asked him whether I could make a mold of his hands, something
that we had done during the workshop. He wasn't interested. However, he did
volunteer to have me make a mold of his face. I don't understand it, but that
was his preference. I think he is at an age where the idea of sticking straws
up his nose is attractive!
Up to now, the largest mold I attempted was that of a large leaf! But, off
we went to make a mold of my nephew's face. We worked out signals and I kept
asking him questions so that he knew he wasn't alone and we could pull the
mold off at any time if he was uncomfortable. He was really good about the
process. I took pictures of him so that he can show all of his friends what
he looked like with plaster on his face and straws up his nose!. He's
volunteered to let me make another mold of his face and his hands as well
during his next visit.
There are a few problems with the mold that I thought someone might be able
to help me with.
- First, there is vasoline on the mold. Should I clean it off? If so, how?
If not, why not?
- Also, there are a few cracks in the mold. I think that they may have
happened because my nephew moved a bit before the plaster had hardened. There
is also a place where the plaster was thin and I now have a little hole. Can
I patch these up with some new plaster? If so, how? Any pointers?
I learned a few things during the process as well. One thing that I thought I
might pass along has to do with the smell of vasoline. When I began to put
the vasoline on my nephew's face, he started making really ugly faces because
of the awful smell. He likes the smell of vanilla flavoring, so I added a few
drops to a gob of vaseline, mixed it in, and finished the job on his face.
The grimaces disappeared.
Thanks for your help.
Shula
PurpleLama@aol.com
currently existing in Baltimore, MD USA
but (southern) California dreaming. Anyone want to buy a multifamily house in
Baltimore so that my CA dreaming can become a reality?
Cheryl Sculley on thu 16 jul 98
----------------------------Original message----------------------------
Hello,
I am having a problem with moldmaking. I would appreciate some information
about what I make my positives with. Usually I do my design work in clay and I
do not have any problems. In college, we used plasticine and a mold soap and
again - no problems. I bought some Plastalina by Van Aken to sculpt in
while I
was away from the studio. Not my choice, but, both art stores only carry
Plastalina instead of plasticine. The package says that it is "a pigmented oil
base modeling compound, non-toxic and never hardening." Here is the problem:
I made my positives, poured my molds and removed the plastaline. Most of my
molds have been drying for about 2 weeks and I still have a heavy, oily, waxy
feeling buildup inside the molds. I have wiped , buffed with a toothbrush and
tryed to remove the film with pressed clay to no avail. I wanted to use these
molds as press molds for sprigging but if they won't absorb moisture
through the
oil buildup what good are they? What did I do wrong? Can I save my molds?
Should I pour slip in them a couple of times and see if that pulls any of the
oil out?
I checked back in my CM's as far as 89 and read some good articles on slip
casting and mold making but saw no references to anything other than clay for
model making. I also went to my textbooks. Nothing there either. I even
called a couple of rubber mold making companys and did not get an answer. The
obvious answer is to go back to using clay only, but as I hate to sit idle when
I am working away from home, I had hoped to use something that does not dry out
in this heat. Needless to say, I hate for all that work to go to waste if I
cannot use the molds.
Any help would be gratefully appreciated.
Thanks,
Cheryl in Chattanooga
Cheryl J. Sculley
cjsculley@mindspring.com
Ross Hartman on mon 20 jul 98
Cheryl;
I believe the reason you will not find much about the materials and
techniques you are asking about is that they are not well understood by
too many, the process has become sort of a lost art.
I have been making molds for 30 years.
Plastalina is the compund that I use in the case of making a first rough
master, what I refer to as a waste mold. the only thing you are tring to
accomplish in the plastilina stage is finding the shape and the parting
line. After this you must do a certain amount of scraping and shaping
(with all the typical clay and sculpting tools). Then you size the
inside of the waste mold, you see it was never meant to cast slip into,
and you pour a solid plaster plug.
I make the plugs of various mixtures of USG. US#1 pottery plaster ,
Hydrostone and Hydrocal. the Hydrostone being the most dense gypsum
material of the three. If you make a plug of solid hydrostone you will
get a very hard master to work on (i.e. carve, sculpt, sanding with very
fine WetOrDry sand paper etc.). If you pout a solid plaster plug you
will get much more thermal expansion which could damage the half of the
waste mold you want to save for the cradle of the next mold in the
process.
In any case size the wastemold well, and let the plug cool completely
before trying to remove it. It will reduce the possible undercut
resistance to parting, and will just generally be easier.
Hydrocal is about the right density for the plug pouring, you can make
it a little harder by adding some hydrostone, or softer by adding some
plaster. Only experience will tell you for the materials you are working
with.
Then in a series of steps where you continually refine the halves of the
mold (e.g. a 2 piece mold) the lands at the seperation, checking for
proper relief, making sure that the detail is there that you want you
can eventually make a plaster cast mating pair that you could use for
slip casting.
In mold making we take it a step further and we make a master mold,
called a case mold (out of pure hydrostone) and this gives you the means
to produce numerous production copies of the original so that you can
cast as many pieces as you need in your production schedule for a given
day.
I could write a book
Hope this helps, I'll help more if you have some more specific
questions.
L8R/Ross
Clyde Tullis on mon 20 jul 98
Cheryl,
When are you taking your origonal from the mold? As soon as it cools? It sounds
like your leaving the origonal in too long.
Clyde
Cheryl J. Sculley wrote:
>
> ----------------------------Original message----------------------------
> I am having a problem with moldmaking. I would appreciate some information
> about what I make my positives with. Usually I do my design work in clay
>and I
> do not have any problems. In college, we used plasticine and a mold soap and
> again - no problems. I bought some Plastalina by Van Aken to sculpt in
> while I
> was away from the studio. Not my choice, but, both art stores only carry
> Plastalina instead of plasticine. The package says that it is "a
>pigmented oil
> base modeling compound, non-toxic and never hardening." Here is the problem:
>
> I made my positives, poured my molds and removed the plastaline. Most of my
> molds have been drying for about 2 weeks and I still have a heavy, oily, waxy
> feeling buildup inside the molds. I have wiped , buffed with a
>toothbrush and
> tryed to remove the film with pressed clay to no avail. I wanted to use
>these
> molds as press molds for sprigging but if they won't absorb moisture
> through the
> oil buildup what good are they? What did I do wrong? Can I save my molds?
> Should I pour slip in them a couple of times and see if that pulls any of the
> oil out?
> Cheryl J. Sculley
> cjsculley@mindspring.com
Dana Henson on mon 20 jul 98
Coat your clay with a thick coating of vaseline. It will not dry out and you
can use it over and over again if you keep it in a plastic bag in between
making molds. I have used the same piece of clay for making molds for six
months or more.
Dana Henson
(In Pilot Point, Texas where it's hot as hell)
Jeff Lawrence on tue 21 jul 98
Cheryl in Chattanooga was asking about molds:
>I made my positives, poured my molds and removed the plastaline. Most of my
>molds have been drying for about 2 weeks and I still have a heavy, oily, waxy
>feeling buildup inside the molds. I have wiped , buffed with a toothbrush
and
>tryed to remove the film with pressed clay to no avail.
Hello Cheryl,
You might try spraying with non-diluted isopropyl alcohol. THis works for me.
Good luck,
JEff
Jeff Lawrence
jml@sundagger.com
Sun Dagger Design
Rt. 1 Box 394L
Espanola, NM 87532
vox/fax 505-753-5913
Andrew Buck on tue 21 jul 98
On Mon, 20 Jul 1998, Russ Hartman wrote:
> Subject: Re: Plaster molds
>
> I believe the reason you will not find much about the materials and
> techniques you are asking about is that they are not well understood by
> too many, the process has become sort of a lost art.
>
> I could write a book
GOOD IDEA. I, too, have looked for a book on mold making without finding
one that told me as much as your post did. But when you do, please, put
in plenty of pictures for those of us with learning disabilities. ;)
Andy Buck
Raincreek Pottery
Port Orchard, Washington
Wayne S Bien on fri 19 may 00
You can get plaster to release from plaster by using Murphy's Oil Soap. I
have always coated the mold with 5 coats before pouring the cast.
Wayne Bien
----- Original Message -----
From: Priscilla Wilson and/or Janice Lymburner
To:
Sent: Friday, May 19, 2000 2:59 PM
Subject: Plaster molds
Hello... This is my first time being in a newsgroup. Thanks in advance for
anybody's help!
I'm trying to find a way to make plaster release from plaster. (There are
reasons why the mother mold really has to be plaster or something other than
clay.) I'm pretty sure the green soap and burnishing won't work for me
because the surface is VERY rough-textured. I don't see how I can burnish it
adequately without ruining the mold! Am I trying to do the impossible???
Would friendly plastic be something to try for the mother mold?
Also, I want to try slipcasting with porcelain if I can ever get these molds
made, and I keep reading that porcelain is hard to cast with. In what way?
Or do you think this is true?
Thanks-
Priscilla Wilson
Sautee, GA
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
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Priscilla Wilson and/or Janice Lymburner on fri 19 may 00
Hello... This is my first time being in a newsgroup. Thanks in advance =
for anybody's help!
=20
I'm trying to find a way to make plaster release from plaster. (There =
are reasons why the mother mold really has to be plaster or something =
other than clay.) I'm pretty sure the green soap and burnishing won't =
work for me because the surface is VERY rough-textured. I don't see how =
I can burnish it adequately without ruining the mold! Am I trying to do =
the impossible???
Would friendly plastic be something to try for the mother mold?=20
=20
Also, I want to try slipcasting with porcelain if I can ever get these =
molds made, and I keep reading that porcelain is hard to cast with. In =
what way? Or do you think this is true?
=20
Thanks-
Priscilla Wilson=20
Sautee, GA=20
=20
eden@SOVER.NET on sat 20 may 00
I also always use either mold soap from the clay supplier or Murphy's. My
rule of thumb is sponge on the soap with a sponge full of hot water and
then rinse the sponge a bit and rub again and again with the hot water and
sudsy sponge. Repeat this process at least 5 times. You will see the
water start to bead up on the plaster surface. Then you repeat twice more
for insurance. Works every time. PS If you go away for awhile and the
surface dries then repeat the process at least afew cycles before proceeding.
Eleanora
..........
Eleanora Eden 802 869-2003
Paradise Hill
Bellows Falls, VT 05101 eden@sover.net
bgioia10 on sat 20 may 00
>I'm trying to find a way to make plaster release from plaster.<
==========
I started out using soap as a releasing agent for plaster on plaster.
Then used vaseline for awhile, ultimately finding it too
thick and left brush marks...also clean up is a hassle.
I'm now using shaving cream from the squeeze tube, its water soluable
and works very well in all aspects, particulary the way it leaves
a lovely waxy film when dry.
For mother mould release where I need more coverage
I use a thin clay slip...the plaster absorbs the water and leaves
a film of clay as a barrier, experiment for best reults.
Also a red clay can be useful as a visual guide for locating the seam.
I use sections of burlap to strengthen the plaster mother mould.
I think that it is your best bet for mother mould material.
Goodluck,
Bruce
Annette Frank on sat 20 may 00
Priscilla, there is a lot on this in the archives. Mold soaps etc. has been discussed. I saved a lot of it, if you can't find info, let me know and I send you old posts.
Annette
Priscilla Wilson and/or Janice Lymburner wrote:
> Hello... This is my first time being in a newsgroup. Thanks in advance for anybody's help!
>
> I'm trying to find a way to make plaster release from plaster. (There are reasons why the mother mold really has to be plaster or something other than clay.) I'm pretty sure the green soap and burnishing won't work for me because the surface is VERY rough-textured. I don't see how I can burnish it adequately without ruining the mold! Am I trying to do the impossible???
> Would friendly plastic be something to try for the mother mold?
>
> Also, I want to try slipcasting with porcelain if I can ever get these molds made, and I keep reading that porcelain is hard to cast with. In what way? Or do you think this is true?
>
> Thanks-
> Priscilla Wilson
> Sautee, GA
>
>
> ______________________________________________________________________________
> 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.
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