A huge graphite crucible, fired by a furnace, is filled with bronze ingots that are melted. The metal begins to melt at 1700°F. Bronze “seizes” (stops flowing) when confronted with cold, which might occur if molten bronze was poured into a room temperature shell; therefore at the same time the bronze is being blasted by a natural gas furnace, the ceramic shell is heated in a kiln to approximately 1100°F.
When the “Dance of the Pour” begins, the crucible is lifted by crane out of the gas furnace. At the same time, the glowing ceramic shells are brought out of the kiln to the pour area. Two artisans operate the crane that holds the crucible in a “jacket.” The artisan with the controls is the “lead pour,” the artisan maintaining the crucible balance is known as the “deadman.” A third member of the pour team pushes away dross and slag on the surface of the molten bronze.
The entire pour is very fast and very precise; one crucible of bronze holds 100 lbs and can fill one or One large shells or 4 or more small shells. The first pieces poured are those with thin walls and intricate details; requiring hot, fluid bronze to move throughout the channel system. The alloy cast at Artworks is known as Silicon Bronze. The metal is made up of the following elements: COPPER 94.0%, MANGANESE 1.1%, SILICON 3.9%, TRACE ELEMENTS 1.0%. Silicon is an additive that helps the “flowability” of the bronze. It achieved widespread use during World War II when lead and tin were in short supply