Our Process
Most of our work is produced using the ‘lost wax method’ a process that is thousand of years old. Put simply it involves ‘investing’ the wax pattern, melting out the wax to form a mould and pouring the metal into the cavity.
Sounds simple?
Here are some of the steps commonly involved in our studio process.
1
Scuplt the Piece
Clay is one of the most common mediums often supported by a metal armature
2
Create the Mould
Once the piece is leather dry apply coats of a silicon rubber to form an elastic mould and a supporting mother mould
3
Create a Wax Replica
Using melted microcrystaline wax fill the mould to make a pattern resembling the original clay. This wax is often hollow to reduce the amount of bronze required.
4
Create Sprues
Sprue the wax using a stronger spruing wax to add pouring cup, runners and risers. This provides a way of filling the shell with metal and allowing gasses to escape.
5
Create a Ceramic Shell
Invest the sprued wax by coating it with a ceramic shell. This is a high tech material and requires numerous coats of coloidal silica, zircon and calcined flint clay.
6
De-Wax the Investment
De-wax the shell using an electric kiln at temperature around 300ºC. Test and repair the shell if necessary as the expanding wax is capable of cracking the shell.
7
Fire the Shell
Fire the shell in the kiln to 950ºC to ‘set’ the ceramic shell material.
8
Pour & Remove Shell
Melt the silicon bronze in the induction furnace to about 1150ºC.
Remove the shell from the kiln and the crucible from he furnace and pour the molten metal into the shell cavity.
Once the metal has solidified drop the still hot shell filled with metal into a metal container filled with water and crack off the shell. Then sandblast to remove the last of the shell.
9
Clean the Piece
Cut off the metal sprues and repair any defects. ‘chase’ the metal surface and finish with sanding and polishing tools
Sandblast the piece to provide a finished surface suitable for accepting patina chemicals. There are hundred of recipes available but the most common are ferric nitrate and cupric nitrate often preceded by liver of sulphur.
10
Finish the Piece
Once the patina has been applied treat with bees wax and buff and polish.
Mount the piece on the plinth, base or pedestal. We tend to use local Toowoomba black and pink granites and local sandstones for much of our finished sculptures.
