Technical Notes on Castings
the lost wax method is used for casting bronzes in,
or with the possibility of, limited editions. The
All the bronzes in this exhibition are UNIQUE bronze casting done by a lost wax method. Unlike the typical process above there is no intermediate work and flexible moulds, as I work directly with in the wax. I find fabricating directly in the wax allows me the expression of more open and fluid original forms.
I use different two waxes (which from memory ) are;
The yellow is the cheaper (always an important point) and tends to have the greater tensile strength of the two, unfortunately the butter like surface is very difficult to see detail on. The Victory Brown is great for detail though a little soft at times.
The one-off wax orginals are then taken to a foundry for casting. The foundry use the ceramic shell method. The ceramic shell, is basically a porous shell produced by dipping the wax patterns (the work with runners and riser attached) into a slurry of fine (approx. 200 mesh) refractory clay then stuccoed with a coarse grit of similar material. The process is repeated building the shell up in layers ( 5-9 layers depending on the size of the piece).
The ceramic shells still containing the wax are then fired, burning the wax out in the process. While the moulds are still hot the molten metal is poured in. The metal used is a "Silicon Bronze", approximately 95% Cu, 4% SiO2, 1% Mn.
All my bronzes casting is now done by;-
Copyright Shaun Gray (c) 1997