The ancient skill of the lost wax process, or cire pirdue, probably predates written history, though it wasn’t until the 10th century that bronze casting in India reached its aesthetic and technical zenith with the creation of the Chola Bronzes. Then as now, copper was plentiful while tin was rare, so bronze was reserved for high-value objects such as sacred icons. Although its composition varies widely over time, place and culture, bronze is generally thought of as an alloy of 8 or 9 parts copper to 1 or 2 parts tin. Today ‘bronze’ is used to loosely describe a broad spectrum of copper alloys, some of which contain little or no tin at all, rendering the term ‘bronze’ almost meaningless. Museums and historical texts now use the term ‘copper alloy’; however, I prefer to use ‘bronze.’
For millennia the lost wax process has followed the same sequence;
• First, a wax mould, or positive, is created from the original model, or maquette.
• The wax maquette is covered in several layers of a liquid medium (river mud in Tamil Nadu, liquid ceramic in the West) which dries to a hard shell,
• The shell is heated in a kiln until the wax melts out completely, leaving a hollow void in the shape of the maquette,
• Molten bronze is carefully poured into the mould and allowed to cool,
• The mould is carefully destroyed, revealing the figure within.
• The labour intensive process of final finishing, or chasing, begins.
• The finished piece is rubbed down with coconut oil to protect the new bronze from corrosion, or a patineur applies a custom patina and a lacquer.