The
idea here is to create a version of the
desired shape in wax which is encased in a
ceramic. The whole thing is then heated so
that the wax melts leaving the void into
which the metal is poured.
There are two main ways in which the wax can
be created. Most common for small parts like
door furniture and so on where you might
want multiple copies is for a flexible
rubber mould to be formed around the
prototype, which is then used for making
waxes. These in turn are stuck together into
a “tree” which is coated with successive
layers of ceramic until a mould is created
thick enough to withstand the heat and
weight of the molten metal. The metal is
poured in and after cooling the ceramic case
knocked off to reveal the metal castings.
For one-off work like
sculpture, a multi-part mould is taken off
the original, reassembled as a hollow shell,
into which successive layers of wax are
poured. The middle part is then filled with
sand, the mould taken off, and ceramic built
up on the outside as before. Heat the whole
thing, lose the wax, and fill the cavity
with metal.
For
an account of the process on a fairly large
scale Cellini’s account of casting his
statue of Perseus is a good read, always
remembering that he was never one to
understate his achievements! While our own
flying pig can’t claim the same
provenance, the process used is much the
same.
The
pictures show:
(top)
Our
tame flying pig - only about 12mm long - who
sits proudly on the handlebars of members of
a motorbike club. All the detail of the
original features in the copies we made.
(upper
middle)
The detail on a carved table leg cast hollow
in bronze.
(lower
niddle)
A re-created sconce, the delicacy and detail demanding the
lost-wax process.
(bottom)
Cast from nature, a part of a 1.2m long
doorhandle cast from a branch.
