Sculptures made from metal are often cast in lost wax molds.
This allows the artist to design using wax instead of sculpting the metal
directly. Wax is far more malleable and easily formed than metal, so the design
can contain more detail. The wax model is encased in plaster, then the mold is
heated so that the melting wax flows out. The plaster is then filled with
molten metal, which can be unmolded once it cools.
Instructions:
1. Create a wax model of your sculpture. This model should have
all the details and proportions that you want the finished product to have. You
can use a lamp to keep the wax warm and moldable, and you may want to use
sculpting tools to help create the look you want.
2. Attach two rods of wax at the bottom of the sculpture. This
will form a channel through which you pour the molten metal and will allow air
inside the mold to escape. You may need to add other rods of wax between
elements of the design to ensure that the metal fills the mold fully --- if you
pour into the feet of a statue of a person, the arms might not fill unless a
channel exists to divert some of the metal into the hand cavities.
3. Mix the plaster of Paris into water so it reaches a
consistency of thick paint. Brush this mixture onto the wax model, making sure
to cover all the details but leaving the ends of the rods at the bottom
plaster-free. Allow to dry for two days. Paint on another thin layer and let
that layer dry, then repeat.
4. Mix a thicker batch of plaster and cover the thin layers in an
inch-thick layer of plaster. Allow this layer to fully dry.
5. Smear petroleum jelly on the inside of a plastic bucket or
another vessel large enough to hold your statue. Place the statue in the bucket
with the exposed wax rods at the top, then fill the bucket with plaster. Allow
to dry, remove from the bucket and then heat the mold with the exposed rods of
wax facing down. The heat will melt the wax, which will flow out of the mold,
leaving an empty cavity ready to be filled with metal.
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