According to the J. Paul Getty Museum’s Department of Antiquities, the earliest Greek bronze sculptures were created using a technique called sphyrelaton. This word, as explained by the Metropolitan Museum of Art, translates to English literally as “hammer-driven.” Used primarily in the era prior to about 500 BC, this method used sheets of bronze. The sheets were cut into the parts needed for the sculpture, then hammered into shape and joined together to form the whole.
This Greek bronze sculpting technique has been dated to the late Archaic period. According to the Metropolitan Museum of Art’s Heilbrunn Timeline of Art History, that period began at approximately 500 BCE. The method is described as being a comparatively simple one. The artist creates a wax sculpture of the intended bronze piece, then the wax sculpture is coated with clay. Once that hardens, the wax is removed, leaving the clay shell. The shell is filled with molten bronze, and when that hardens completely, the clay is broken away.
Historical texts that have survived to the modern era, such as the writings of Pliney the Elder and Pausanias, describe this technique of Greek bronze sculpture as being developed by the 6th century Samian sculptors Theodoros and Rhoikos. According to the Metropolitan Museum of Art, this technique developed because “the physical properties of bronze do not allow large solid casting.” To make larger bronze sculptures via casting, another method had to be devised. A clay version of the sculpture is made, then covered with wax. That is covered with an outer layer of clay. Vents are incorporated to ease the flow of the melted metal and, for large pieces, metal rods are used in the core of the structure for additional strength. The wax is melted out and replaced with bronze. After it hardens, the outer clay is broken away and the sculpture is ready for the finishing touches.
In the indirect hollow lost-wax casting process, a foundation form is preserved and can be used again, according to the Metropolitan Museum of Art. After the initial form is made, the one that served as the core in the direct process, another form is made around it, in sections. That form is designed to be removed and preserved. The sectioned form is put together and a test run is conducted with beeswax to make sure all necessary details were achieved. That form is then used to make another set of mold sections, which is what is actually used to make the sculpture in a process basically the same as the direct process. The outer clay layer is broken away after the bronze solidifies, with the original form that it was made from preserved for reuse.