Llewellyn Kouba on mon 3 nov 03
I have never used plasticine and would like to know how to use it with mold
making. I want to experiment with it for tile making and pull a plaster
mold from plasticine. What are the best types (name brands) to use. I no
longer have any of the original packing for the two types I have. One is
very gray and clay like and the other is black and more glossy and wax like
in appearance. Both seem to be in various states of 'hard' and not sure
they are still OK but the clay one seems to move around once you get it
going and warmed up. Any tips to watch out for in making a flat tile
mold....undercuts of course. Is is plasticine better to use than clay
itself and what is the best medium to use? thanks.
Llewellyn Kouba
Abbey Pottery
John Rodgers on mon 3 nov 03
Oil clays are better to use for modeling for mold making than regular
earthen clays because the earthen clays shrink, and the oil clays do
not. That being said, in my experience, of the various oil clays around
my preference by far are the Chevant clays. Plastilene, plasticene,
plastilina are the most common trade nameed oil clays, and have a sulfur
base. I do not like how it smells, stinks really, and, if you ever have
the occasion to make a rubber mold, the sulfur kills the catalyst in the
rubber and you are left with a gooey, sticky mess that is more difficult
to get off of everything than the worst tar-baby on a hot summer day.
Boy-o-Boy-o-Boy is that stuff bad news. Plastilene clays also give up
oil into the plaster when the heat from the setting plaster hits it, do
you really need to seal it for best performance.
With Chevant clays - sort of a cross between pink and brown - you have
no nasty smell, it does not bleed oil, and silicone mold release works
really well with it.
You do need a heat gun to effectively work with the various oil clays.
Finally, by far my preference for modeling is to work with wax. It can
be carved, or it can be added back if a mistake is made. yet is is hard
enough to accept handling without getting "Mooshed" . I used to work
with oil clays exclusively until a jeweler friend introduced me to the
wax world of the jeweler. I adapted the wax designing and sculpture to
clay work and mold making, and have been a very happy model and mold
maker ever since, creating all kinds of molds to be used in slip casting
of clay.
Regards,
John Rodgers
Chelsea, AL
Llewellyn Kouba wrote:
> I have never used plasticine and would like to know how to use it with
> mold
> making. I want to experiment with it for tile making and pull a plaster
> mold from plasticine. What are the best types (name brands) to use. I no
> longer have any of the original packing for the two types I have. One is
> very gray and clay like and the other is black and more glossy and wax
> like
> in appearance. Both seem to be in various states of 'hard' and not sure
> they are still OK but the clay one seems to move around once you get it
> going and warmed up. Any tips to watch out for in making a flat tile
> mold....undercuts of course. Is is plasticine better to use than clay
> itself and what is the best medium to use? thanks.
>
> Llewellyn Kouba
> Abbey Pottery
>
> ______________________________________________________________________________
>
> 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.
>
Snail Scott on mon 3 nov 03
At 11:06 AM 11/3/03 -0700, you wrote:
>I have never used plasticine and would like to know how to use it with mold
>making. I want to experiment with it for tile making and pull a plaster
>mold from plasticine. What are the best types (name brands) to use...
Plasticine is a great medium for making mold
patterns. You get an unlimited 'open time' for
working your design, no shrinkage issues, and
the stuff can be reused almost indefinitely
without reprocessing. There are many brands,
and many of them come in various colors and
hardnesses.
For rubber mold making, one absolute is to use
NO type containing sulfur, which is a common
additive to improve handling in many plasticines.
(It prevents the proper curing of mold rubber.)
Since you are using plaster, not rubber, you
can regard this as irrelevant to you, unless
you think you might someday make rubber molds.
So, I would concern yourself principally with
the level of hardness. Soft plasticine allows
you to finger-shape the contours and leave the
surface with a free and loose expression. Hard
plasticines allow for clean and sharp carving
and are good for tight detail and geometry.
It's an entirely personal preference.
Remember that what might be 'soft' in the
summer heat will be harder in cold weather.
Also remember that you can use low heat to
soften hard plasticine to a desired level of
workability and allow it to stiffen after the
work is done.
Choice of color is also personal, as the color
won't have any impact on the final piece. I
prefer a neutral color that's not too dark,
so I can see whay I'm doing, but not too light
so that it won't show distracting grubby marks
after repeated use. (Bright colors are fun, but
I'd skip them. Ran out of my regular brown once
and had to use the only color left at the local
hobby shop - bright red! I saw green ghosts
shaped like my sculpture whenever I looked up!)
;)
Chavant is a popular and widely-available brand
sold directly and through art stores. It's high-
quality stuff, used in the auto industry for
their body-contour models. It comes in sulfur
and non-sulfur formulas.
The Van Aken brand is easy to find in hobby shops
as it's popular with kids and for claymation. It
comes in multicolor packs, but the 5# blocks in
neutral colors are also stocked by many stores.
(Aaron Brothers frame shops are the cheapest
source I've seen.) It's all sulfur-free, but
only has one hardness - soft.
Roma Plastilina is the 'old-school' brand -
it used to be about the only one. It comes in
several hardnesses and neutral shades. It's OK.
I don't use it because I often do rubber molds
and the Roma stuff is high-sulfur, so I don't
even want it around the studio. That's my own
bias, though, and may not be relevant for you.
Most art-supply shops stock it.
J.F. McCaughan makes a nice variety of sulfur-
free plasticine in a variety of hardnesses. It
needs to be purchased directly from them, last
I checked.
Sculpture Magazine has lots of ads for plasticine
suppliers and manufacturers in the back of each
issue.
You can get away without using a mold release, as
the plasticine will release naturally from the
plaster, but I would still use something. Murphy's
Oil Soap from the supermarket or Wal-Mart will
work fine. You'll get a cleaner release and a
better mold surface. And you may want some sort
of mold release anyway, to free up your cottle
boards.
Don't forget to calculate the shrinkage of your
intended clay body, and make the mold pattern
sufficiently large to offset that shrinkage.
-Snail
Snail Scott on tue 4 nov 03
At 06:41 PM 11/4/03 -0700, you wrote:
>I made the Cottle boards out of pressed wood with formica surface...
Mine are the same - I got it from a place that
does kitchen remodeling. They gave it to me for
free, and even offered to cut it to size for me.
The formica makes a great moistureproof coating
and the particleboard is nice and flat.
-Snail
Llewellyn Kouba on tue 4 nov 03
Snail,
Thanks for all the great input on Plasticine and comparison of brand names.
I know so little about this and have never used it. Today I got all the
boards cut out and assembled and tomorrow I will be ready to pour some
plaster. I have worked with plaster before so I don't for see any problems
there.
I made the Cottle boards out of pressed wood with formica surface in hopes
that my plaster won't bond to this and will also use a mold release. I am
looking forward to playing around with the plasticine and will be fun to do
the relief and carving....keeping in mind not to have undercuts of
course. It should be a fun project and thanks to all who have added input
on this.
Llewellyn Kouba
Abbey Pottery
At 02:43 PM 11/3/2003 -0800, you wrote:
>At 11:06 AM 11/3/03 -0700, you wrote:
> >I have never used plasticine and would like to know how to use it with mold
> >making. I want to experiment with it for tile making and pull a plaster
> >mold from plasticine. What are the best types (name brands) to use...
>
>
>Plasticine is a great medium for making mold
>patterns. You get an unlimited 'open time' for
>working your design, no shrinkage issues, and
>the stuff can be reused almost indefinitely
>without reprocessing. There are many brands,
>and many of them come in various colors and
>hardnesses.
>
>For rubber mold making, one absolute is to use
>NO type containing sulfur, which is a common
>additive to improve handling in many plasticines.
>(It prevents the proper curing of mold rubber.)
>Since you are using plaster, not rubber, you
>can regard this as irrelevant to you, unless
>you think you might someday make rubber molds.
>So, I would concern yourself principally with
>the level of hardness. Soft plasticine allows
>you to finger-shape the contours and leave the
>surface with a free and loose expression. Hard
>plasticines allow for clean and sharp carving
>and are good for tight detail and geometry.
>It's an entirely personal preference.
>
>Remember that what might be 'soft' in the
>summer heat will be harder in cold weather.
>Also remember that you can use low heat to
>soften hard plasticine to a desired level of
>workability and allow it to stiffen after the
>work is done.
>
>Choice of color is also personal, as the color
>won't have any impact on the final piece. I
>prefer a neutral color that's not too dark,
>so I can see whay I'm doing, but not too light
>so that it won't show distracting grubby marks
>after repeated use. (Bright colors are fun, but
>I'd skip them. Ran out of my regular brown once
>and had to use the only color left at the local
>hobby shop - bright red! I saw green ghosts
>shaped like my sculpture whenever I looked up!)
>;)
>
>Chavant is a popular and widely-available brand
>sold directly and through art stores. It's high-
>quality stuff, used in the auto industry for
>their body-contour models. It comes in sulfur
>and non-sulfur formulas.
>
>The Van Aken brand is easy to find in hobby shops
>as it's popular with kids and for claymation. It
>comes in multicolor packs, but the 5# blocks in
>neutral colors are also stocked by many stores.
>(Aaron Brothers frame shops are the cheapest
>source I've seen.) It's all sulfur-free, but
>only has one hardness - soft.
>
>Roma Plastilina is the 'old-school' brand -
>it used to be about the only one. It comes in
>several hardnesses and neutral shades. It's OK.
>I don't use it because I often do rubber molds
>and the Roma stuff is high-sulfur, so I don't
>even want it around the studio. That's my own
>bias, though, and may not be relevant for you.
>Most art-supply shops stock it.
>
>J.F. McCaughan makes a nice variety of sulfur-
>free plasticine in a variety of hardnesses. It
>needs to be purchased directly from them, last
>I checked.
>
>Sculpture Magazine has lots of ads for plasticine
>suppliers and manufacturers in the back of each
>issue.
>
>You can get away without using a mold release, as
>the plasticine will release naturally from the
>plaster, but I would still use something. Murphy's
>Oil Soap from the supermarket or Wal-Mart will
>work fine. You'll get a cleaner release and a
>better mold surface. And you may want some sort
>of mold release anyway, to free up your cottle
>boards.
>
>Don't forget to calculate the shrinkage of your
>intended clay body, and make the mold pattern
>sufficiently large to offset that shrinkage.
>
> -Snail
>
>______________________________________________________________________________
>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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