The Lost Wax Process of Casting Bronze Sculpture.
This method of casting bronze is an ancient craft, at least 5,000 years old. It remains essentially unchanged but has been improved with modern technology.
The first step in the creation of a bronze sculpture is a mental concept nourished and inspired by observation. If this is a large or complex bronze we usually design a maquette (a miniature scale model) of the proposed larger one.
This gives one a good idea of what the finished bronze will look like before the actual model is begun, allowing for manipulation and experimentation on a small and convenient scale.
The next step is the creation of a model in clay or wax that will be exactly like the proposed sculpt. In doing this one must anticipate mold making, welding joints, etc. so that future steps are as easy as possible.
Next a rubber and/or plaster mold is made of every part of the sculpture. Sometimes there is one piece, sometimes many. After the mold is made the clay or wax model is of no further use and is usually recycled. Clay that is a ram today may be a moose tomorrow.
Into the mold hot wax is brushed and poured to form a hollow wax pattern identical to the original model. For every bronze that will be made there must be a wax pattern.
After wax gates, vents and channels are attached to the wax pattern it is ready to be invested. This means a mold of a refractory material will be built around and into the hollow wax pattern. This is done by alternately dipping the wax into liquid silica and then powered silica, allowing each coat to dry for several hours. After about a week the mold is built up to the thickness needed to hold molten bronze.
The sections are cast and all welded together. Then the foundry craftsmen chase or fix and repair all the seam lines and imperfections. The final steps are to sand blast and patina the metal to the desired effect and colors and to wax and polish and last to sign and number the edition.