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Lesson Plans


Plasticene

[ Thread ][ Subject ][ Author ][ Date ]
wrapf (wrapf)
Tue, 12 May 98 14:58:33 EDT


Here's a copy of the recipe that I copied and saved as it appeared several
months ago.

Bill R.
***********************
Hello All,

I'm not sure about the dangers of using motor oil in this form. I'm sure
someone out there has a more expert opinion about its safety. If there
is a good substitute for motor oil I'd like to know. When I was in
graduate school I mixed my own oil based clay for sculpting using a
formula I got from my teacher. If potential dangers from motor oil
aren't a problem or concern to you the formula was:

6 quarts motor oil (non-detergent)

20 pounds Brown Victory Wax (micro crystaline wax)

50 pounds fire clay

We had a half of a 30 gallon drum propped up over the burner from a gas
water heater. Heat the oil and add in the wax, stirring with a 1" x 4" x
4' paddle until the wax is melted. Be very careful not to set the whole
mixture on fire. Once the wax was melted stir in small amounts of the
fire clay until its all mixed in. Turn off the burner and let the
mixture cool down a bit. Then, using the paddle, scoop out the clay onto
a sheet of very heavy plastic spread out on a concrete floor. This stuff
is very HOT and can cause a serious burn if you get it on your skin, be
careful. If the clay melts the plastic its too hot and you should wait
longer before taking it out. If you leave the mixture in the drum to
cool its often difficult to get out so its best to remove it while its
warm. For a softer clay you can add some Vasoline (petroleum jelly) to
the liquid oil/wax. For a firmer clay use less oil and more wax.

For any novices out there, this clay cannot be fired. It doesn't dry and
won't harden. You use this type of clay to model with and then make
molds from what you have sculpted.

cheers

Kim

Oil clays.....modeling clay......"plasticine" need to be made with
NON-drying oils or plasticizers. Using linseed or similar oils will result
in a clay that gets stickier and harder as time goes on. Just like what
happens to oil paints.
The commercial formulas are usually guarded secrets. There are some of the
basic and older formulas out there from old books and manuals.

One old copy of Plasticine-like clay uses kaolin and finely ground sulfur (
sulfur is quite a common ingredient ).

Kaolin 67 parts to sulfur 33 parts. Mix thoroughly. To the basic clay mix
you then add a plasticizer. A mix of one part to three parts clay mix. (
approx. / or to your own feel depending on plasticizer used. )

Plasticizers can be mineral oil, petroleum jelly, glycerin/lanolin mix
40/60, non-drying oil.
Beeswax, or other waxes are sometimes added to modify stiffness.

That's the basics....very basics from years ago.

----------------------------Original message----------------------------
I just found out that Malcolm Davis will be giving a hands-on teapot
workshop at Worcester Center for Crafts, in Worcester, MA -- on Saturday
and Sunday, March 7 & 8. There will also be a public
slide lecture/pot luck on Friday, March 6, from 6 to 9 PM. I don't know
the cost of this workshop, but for more information, contact the:
Worcester Center for Crafts
25 Sagamore Road, Worcester, MA 01605
phone 508.753.8183
email: craftcenter

If you were to rate the amount of skill required to make a ceramic piece
>what would be your ranking of 15 things. For example:
>1 -15 ( 1- being easiest 15- being the most difficult)
>1- wedging clay ---------------------------------------------- 1
>2- rolling out a slab of clay -------------------------------- 14
>3 -dunking a pot in glaze (glazing a pot) -------------------- 12
>4- painting on slip and stains ------------------------------- 10
>5- cutting slabs using a pattern ----------------------------- 15
>6- attaching two slabs (scoring and mending) ---------------- 9
>7- attaching two pieces of clay (handles, decorations) ------- 11
>8- pulling a handle ------------------------------------------ 7
>9- centering clay on the wheel ------------------------------- 2
>10- loading a kiln ------------------------------------------- 13
>11- throwing a shape that you want to throw ------------------ 5
>12- throwing a 6" cylinder w/ 1 pound of clay ---------------- 6
>13- throwing a bowl ------------------------------------------ 3
>14- even walls ----------------------------------------------- 4
>15- lidded peices -------------------------------------------- 8

THE TWIN ROLLER POTTER'S ASSISTANT

The potter working on a pot on the wheel uses water, or
slip to lubricate the contact between his hands and the clay
that he is working. He applies pressure forces in a highly
controlled way to shape the clay into the desired form.

However, as he continues the added water soaks into the clay,
and it gets softer and softer, and becomes so weak that the pot collapses
under gravity, or the fabricating forces. The master potter
is able to shape his pot quickly, and is more capable of
continuing to form and control the shape as the clay becomes
softer, but eventually he must stop and give the clay a chance
to dry out.

The novice has more trouble with the weakening clay, and
would be greatly helped by a means to apply fabricating forces
without the lubrication water. A solution is to use rollers.
Most anything works. Furniture casters with wheels about 1
1/2 inches diameter and 3/4 in wide are very satisfactory.

The twin roller is a pair of rollers, one that contacts
the interior of the pot, and the other the outside. The
rollers are mounted on the ends of two arms that are linked at
their other ends, and with mechanical means for limiting the
closeness of the two rollers. The separation of the rollers
is controlled by the potters pressure on the arms, or the
activation of the limit stop. A simple design consisted of
two parallel 24 inch 5/8 dia. wooden dowels connected at the
upper end by a strap hinge whose leaves were each bent through
about 45 degrees so that when the dowels were connected they
were about 2 inches apart and parallel. Hangar bolts (5/16")
were inserted into the other ends of the dowels and in line
roller skate wheels were mounted on the hangar bolts. A
simple limit stop was made by drilling 1/4 in holes in the
middle of each dowel and putting threaded 1/4 in rod through
the holes with a pair of nuts on the rod between the dowels to
make the adjustable limit stop.

With such a tool one can form the wall of a pot to a
uniform thickness, and has not needed to add lubricating
water. This gives much more working time with the clay in
optimum condition. The mechanical limit stop makes attaining
a uniform wall thickness much easier. A badly centered pot
turns out well centered after one or two pulls up. Since
water has not been added pot collapse under its own weight is
much less likely. Without this tool my thinnest pot walls
were 3/8 in; with the twin rollers I can prepare pots with
1/4 in walls easily. It is also remarkable to find that as
one works the pot it gets better centered almost
automatically!

************************************************************************

Two pictures of the twin roller tool in operation are on the
internet at:

http://www-astro.physics.ox.ac.uk/~ser/dad.html