Bronze Statuary in Ancient Greece
First used during the Bronze Age, to which it gave its name, bronze has been used throughout history in numerous ways. The ancients used bronze for making armor, weapons, utensils, household items, and some of the finest works of sculpture, an art in which the Greeks excelled.
The ancient Greeks had a long history of making bronze statuary. Temples, shrines, public areas in major cities were filled with images of gods and legendary heroes, statesmen and athletes. Over the course of more than a millennium, the most eminent Greek sculptors created thousands of bronze figures whose influence on large-scale statuary continues to this day.
The Techniques
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Dreros Apollo
Example of sphyrelaton1. Sphyrelaton
Bronze statuary in the Hellenic world began with a technique called sphyrelaton, which literally means "hammer-driven". Sphyrelaton is a simple method in which metal sheets are hammered over a wooden core and then riveted together. This technique was commonly used in the earliest large-scale Greek bronze figures, and in some Classical chryselephantine statues, like the Athena Parthenos at Athens. Sphyrelaton is also exemplified in figures such as those found in the temple of Apollo at Dreros on Crete, made circa 700 BC, and the statue of Zeus Hypatos at Sparta, regarded by Pausanias as the most ancient existing statue in bronze.
2. Lost Wax Casting
By the late Archaic period (500-480 B.C.), sphyrelaton went out of use and lost wax casting became the preferred method for producing bronze statuary. The lost wax casting of bronze is achieved in three different ways: solid lost wax casting, hollow lost wax casting by the direct method, and hollow lost wax casting by the indirect method.
a. Solid Lost Wax Casting
This is the simplest method of lost wax casting. In this technique, the artist first creates a full-sized wax model of the sculpture, which is covered with clay and heated. When the clay has hardened, the wax is removed. The clay mold is then inverted and filled with molten bronze. Once the metal has cooled, the clay model is broken open to reveal the bronze figure, and its surface is smoothed.
b. Hollow Lost Wax Casting (Direct Method)
Pausanias attributes the invention of hollow casting to Rhoikos and Theodoros, two Samian artists who flourished in the early 6th century. (While this may be substantially correct, the process is much more likely to have been borrowed from Egypt than invented independently.)
The hollow casting technique is appropriate for large-scale statues, since it requires much less bronze than that necessary for solid casting.
To create a bronze statue by the direct method, the sculptor first makes a clay model of the approximate size and shape of the intended figure. This model is covered with wax, and vents are added to ease the flow of molten metal. Next, the model is covered again in an outer layer of clay and is heated to remove the wax, creating a hollow matrix. Molten bronze is then poured into the mold until the entire matrix is filled. When the bronze has cooled sufficiently, the mold can be broken open to obtain the bronze figure.
Typically, large-scale Greek sculpture was cast in parts, like the head, torso, arms, and legs. These bronze pieces were then carefully joined by rivets, and small defects were repaired by the insertion of patches of bronze. The eye sockets were left hollow in the casting, and eyeballs of glass, stone, or other materials, imitating the cornea and iris, were inserted. Teeth and fingernails inlaid with silver, lips inlaid with copper, and colored borders on the drapery were added too, contributing to the statue's lifelike appearance.
Hollow bronze statues were much lighter and less brittle than those made of marble, and this allowed the sculptor more freedom to pose the figures. Hence when a Greek bronze statue was copied in marble in Roman times, a support that was not present in the original, often had to be added. The presence of such a marble support is one reason among others for assuming a bronze original.
c. Hollow Lost Wax Casting (Indirect Method)
The majority of large-scale ancient Greek bronze statues were made using the indirect method. In this technique, a model of the statue is made, usually with clay. A mold of plaster or clay is then made around the model to replicate its form. Once dry, the individual pieces of the mold are removed, reassembled, and secured together. Each piece is then lined with a layer of wax. After the wax has cooled, the mold is removed and the sculptor checks to see if all the details have transferred from the initial model, and if corrections are needed. A system of channels and vents is attached to the model, and the entire structure is covered with one or more layers of clay.
As in the direct method, the clay mold is heated to fire the clay and the wax is poured out. Molten metal is then poured in. When the metal cools, the mold is broken open to reveal the cast bronze segment of the statue. Finally, the separately cast parts are joined together.
Archaeological Evidence for Bronze Working
Pheidias' cup
Tools, terra-cotta molds, and a cup inscribed "Pheidias" have been recovered from the site, which dates from 440-430 BC - the period during which the artist had undertaken the construction of the chryselephantine Statue of Zeus, one of the Seven Wonders of the Ancient World. The floor plan of the workshop coincidentally resembles that of the Temple of Zeus at Olympia.