Method
The basic method of lost-wax casting has been widely practiced on the African continent for centuries. While it is difficult to establish how the method was developed or introduced to the region, it is clear that West African sculptors were casting brass with this method for several hundred years prior to the arrival of the first Portuguese explorers along the coast in 1484. The technique requires a great deal of skill, involving extensive knowledge of both pottery and metalworking, and a careful attention to changing temperatures to prevent unwanted cracking or other damage to either the clay mold or to the metal sculpture during the casting process. Some of the earliest and most accomplished bronzeworks found in Africa date to the tenth century and are from a site called Igbo-Ukwu.
The process begins with beeswax, latex, or another material with a low melting point. It must be soft enough for carving fine details, but hard enough to retain its shape. After the wax object has been carved, increasingly coarse layers of clay are applied to the object and allowed to dry. The first and finest clay slips capture the wax details in the smooth mold, and the coarser clay layers provide strength. The entire assemblage is fired, causing the original wax carving to melt away, leaving only a baked clay shell. Liquid metal is poured into the empty mold and left to cool and harden. Later, the clay exterior is broken open, revealing the finished metal object beneath. In direct lost-wax casting, the object produced is always unique, as the mold is necessarily destroyed as part of the casting process.
West African sculptors have elaborated on this basic technique in a variety of ways. Many works were produced through multiple castings and by uniting different sections of a large vessel or figure. In addition, many of the brasses are actually a thin sculpture of hollow metal. In this case, the wax sculpture is formed over a clay core. The two clay parts are attached with spikes. Made from iron, the melting point of the spikes is hotter than either the wax or brass, holding the materials in place through the phases of heating and cooling. If reachable, the clay core is broken up and removed from the interior of the completed brass work.
Bronze, Copper, and Brass
The term bronze is deceptive. Because metallic content cannot be determined from appearance, cast sculptures made from a variety of metal alloys are often all referred to as bronzes. Copper, which is easily worked through smithing, is particularly difficult to cast without the addition of other metals that slow its oxidation rate and improve the flow of the molten metal. Different alloys of copper mixed with zinc, tin, and lead result in what are more accurately referred to as bronzes (copper and tin) and brasses (copper and zinc). The metals used in West African sculptures come from a variety of sources. Tin is plentiful in Nigeria, and in the 1980s copper and lead sources that appear to have been mined were identified in southeast Nigeria. Certainly, however, the greatest periods of casting coincide with the influx of metals into the region from outside. The metals used in Ife bronzeworks were from brass brought across the Sahara by Arab caravans beginning in the twelfth century. In the fifteenth century, copper and brass were brought by Portuguese trading ships, contributing to another increase in metalwork.
The Tada Figure
Among the most well known of the works produced by Ife casters are a series of naturalistic heads. Despite the difficulties, Ife smiths cast many fine works in nearly pure copper. The seated Tada figure, dated to the late thirteenth or early fourteenth century and named for the village in which it was found, is one of the finest works in this tradition. It is hollow-cast and, at 54 centimeters tall, half-lifesize. The sculpture was cast in several separate pourings. Though found on the bank of the Niger River far north of Ife, the work shares the stylistic naturalism of other Ife metal and terracotta works. The naturalistic proportions of head and body and lifelike limbs, arms, and torso are some of the distinctive features of this style. Also characteristic of Ife culture, the figure wears a wrapper with a sash tied on the left hip.
By the time the art world first learned of this piece, it had been reintegrated into contemporary ritual practice. The sculpture of the seated man was scrubbed every Friday with gravel from the Niger’s riverbed by Tada villagers, who believed that this ritual would ensure their own fertility and that of the fish on which they subsist. The abraded surface of the Tada man is the result of this weekly ritual scrubbing.