Have you ever wondered about the mold
making process??? What steps go into those tiny pieces of
plaster that allow you to make beautiful miniature dolls? How does
an artist get from a clay sculpture to hundreds, or even thousands of
production molds available for retail sale? Why do some molds last
seemingly forever and others wear out after only a few pours?
In this demonstration, it is not our
intention to try to teach you mold making, but to teach you ABOUT
moldmaking. We will show you the steps, start to finish that go
into making a highly detailed, high quality plaster mold, and how to
turn one sculpture into hundreds of molds.
||Meet Nicholas. He is sculpted in oil base (a.k.a.
"green") clay. I am hoping that he will make a good
Santa, Father Christmas, shopkeeper, bartender, lamplighter, pirate,
etc. ect. Kind of a man for all seasons.
Using oil base clay has it's good and bad points. It is well
suited for miniatures, since it will not dry out, so no chance of a nose
flaking off as with water base clay. Because there is no drying, there is also no
shrinkage. On the other hand, it is difficult to get a mirror
smooth surface in, which is easier obtained with some other
But it is what I am used to working in, so this is what Nicholas
has been modeled in.
Fortunately, this is as far as I have to go. Larrell now has
the task of turning a single casting into dozens of production
molds. He will take it from here.....
|The clay model has been sealed, and the first step in the
mold making process is just beginning.
The parting line must be determined, and the piece is then
"clayed up" using water base clay. This means that a
base is built beneath and around the model up to the exact parting line
which will determine the two halves of the final mold. Finding the
correct parting line is essential. A mistake can mean undercuts
that will prevent a casting from ever being pulled properly from the
||When the claying up process is completed, the model and
clay are soaped, mold boards are clamped into place. Notice
that the clay bed that the head rests in is smoothly contoured.
|Grade A pottery plaster is carefully
weighed and mixed, and poured into the mold form.
When the plaster is set, the boards are removed, and the water
base clay removed.
||The first half of the mold, with the sculpture still in
place is then placed back into the mold boards, the surfaces prepared, and the second half of
the mold is then poured.
When both halves have completely cured, the casting is removed,
and the mold is allowed to dry completely.
This initial mold is sometimes referred to as a "waste"
mold, although I can not imagine why. Our waste molds are made
with care and precision, and the castings from these initial molds are
of very high detail with minimal seam lines. Perhaps the term
waste mold refers to the fact that if we intend to we will further refine our molds,
proceeding to a master mold and rubber cases, this first mold will
eventually be discarded.
|Because my sculpture was in oil base clay, and I still
have lots of detailing that I want to do, from the initial mold, a wax model is cast.
The wax used is well suited to fine detailing, and to refining the
overall surface of the piece to a perfectly smooth surface. Any
minor changes that are desired can also be made at this
Working with this wax model gives me an opportunity to perfect the piece without fear of accidentally removing
||From the refined wax model, a second mold is
made. This mold is called the "Master" mold. All
surfaces of this mold are as smooth and refined as possible, and all
seam lines are tight.
Because of the extra work done on the wax model, the detailing in
the Master Mold is very sharp and defined.
|The master mold is test cast several times to make sure
that it pours and drains well, and that the casting is sharp and pulls
from the mold easily. Nicholas is such a happy guy, he nearly
leaps out from the mold!
||The master molds are prepared, and then a polyurethane
material is poured over them to create a rubber case. The rubber
case or rubber master is what is used to produce many duplications of my
mold so that I can offer Nicholas for sale as a mold.
|This is the completed rubber case. The inner surface
of the rubber master is a reverse image of what the inside of the mold
will look like. It will be used to mass produce molds for resale.
These molds are referred to as "production molds". The
rubber exactly duplicates all detail in the molds, and if used and cared
for properly, can produce hundreds and sometimes even thousands of
||The rubber cases are filled with properly mixed grade 1
pottery plaster. Molds are allowed to cure while in the rubber
case.Molds are removed, edges trimmed, and carefully inspected for any
pinholes or flaws. Molds with flaws of any kind on the casting
surface are discarded.
| Molds are removed, edges trimmed, and carefully
inspected for any pinholes or flaws. Molds with flaws of any kind
on the casting surface are discarded.
Several production molds can be made per day from a rubber case.
|A lot of care and expertise has gone into creating
your miniature molds. Proper use and care on your part will help
keep them producing clean sharp castings for a long time.
Molds should be completely dry before initial use, and always
tightly banded when cast.
Use the softest brush to remove any dust or dried porcelain from
the interior of your mold. Stiff bristled brushes can scratch the
surfaces, resulting in damaged castings.
Do not use sharp objects to remove porcelain from the inside of
the mold, as the plaster will scratch easily.
Do not over-pour your molds. Pouring molds to the point that
they are very wet (many consecutive castings in a day) will quickly wear
out the fine details in your mold. Instead, cast 2-3 times, and
let the mold dry before recasting.
Take the time to clean up even the outside of your molds before
storing them. It is so much nicer to pour a clean mold than one
with old dirty slip all over it!
Always store molds tightly banded together to prevent chipping or
other damage. A small piece of cardboard over the pour holes, or
storing pour hole side down on a clean shelf will prevent dust on the
inside of your molds.
We hope that you have enjoyed learning about the
many steps that have gone into creating your miniature doll molds!
If you would like information regarding production of molds from your
own sculptures, please email us for further information and a price
estimate. We offer any and all of the steps shown in this
demonstration, as well as manufacture and drop shipment of production
molds. We look forward to filling your mold making needs.