HOW TO MAKE A TWO-PART RUBBER MOLD
OF A COMPLICATED MODEL, PAGE 1
How to make a two part silicone rubber mold
or polyurethane rubber mold.
How to make an RTV rubber mold.
The first photo shows the original model for which we
want to make a mold. What makes this model complicated
• The holes under the neck and tail.
• The holes between the three feet on the ground.
• The leg lifted up and not touching the ground.
• The head and neck turned to one side and not exactly
in line with the body.
• The relatively thin legs.
The first step is to un-complicate the model as much
as possible before making the mold. We can make this
model much less complicated simply by removing the
horse from the base. The base by itself is a very
simple mold - just put the base in a container, seal
the bottom edge of the base with clay so the liquid
rubber does not seep under it, and pour liquid rubber
over it. After the horse and the base are cast
separately, they can be put back together. This also
allows for the flexibility of putting the horse on a
different base, or not using a base at all.
you are the creator of original sculptures that you
will eventually want to make molds from, always sculpt
the main figure separate from the base. And make other
parts as separate objects also. For instance, if this
horse had a rider, you would want to sculpt the rider
as a separate object. If the horse was tied to a
hitching post, you would want to sculpt the hitching
post separately, and so on.
make a two part mold of this horse, we will first bury
the horse in clay, so that one half of the horse is in
clay, and one half of the horse is exposed. This means
one half of the body, one half of each leg, one half
of the head and neck, and so on. The clay will form
what is called the “parting line”. There is no
requirement that the parting line be straight. It can
undulate however necessary to follow the curves of the
Use a pallet board. A good pallet board is a large
plastic board such as those sold as kitchen cutting
boards. Roll out a slab of clay about ½ inch thick on
the pallet board, and lay the horse on it.
small balls of clay, and push them into place around
the horse so they come to the approximate parting
to Page 2
a PDF source list
Includes 26 suppliers of all mold making and
casting materials mentioned in ALL the demonstrations
on this web site, including silicone rubber,
polyurethane rubber, latex rubber, polyurethane
plastic, epoxy resin, polyester resin, molding clay,
foam board, release agents, pottery plaster, Hydrocal,
metal powders, other plastic resin fillers, and
gelatin molding compound. With company names,
addresses, phone numbers, and web sites. Downloads to
your computer as a PDF file.