History
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive, but sometimes with other elements such as phosphorus, manganese, aluminium, or silicon. It was particularly significant in antiquity, giving its name to the Bronze Age. Bronze was significant to any culture that encountered it. It was one of the most innovative alloys of mankind. Tools, weapons, armour, and various building materials like decorative tiles made of bronze were harder and more durable than their stone and copper predecessors.
Initially bronze was made out of copper and arsenic to form arsenic bronze. It was only later that tin was used, becoming the sole type of bronze in the late 3rd millennium BC. Tin bronze was superior over arsenic bronze in that the alloying process was more straight forward and the alloy was stronger and easier to cast. Also, unlike arsenic, tin is not toxic. The earliest tin-alloy bronzes date to the late 4th millennium BC in Susa ( Iran ) and some ancient sites in Luristan ( Iran ) and Mesopotamia ( Iraq ). Copper and tin ores are rarely found together, so serious bronze work has always involved trade. In Europe, the major source for tin was Great Britain 's deposits of ore in Cornwall .
Though bronze is stronger (harder) than wrought iron, the Bronze Age gave way to the Iron Age; this happened because iron was easier to find. Bronze was still used during the Iron Age, but for many purposes the weaker wrought iron was found to be sufficiently strong. Archaeologists suspect that a serious disruption of the tin trade precipitated the transition. As ironworking improved, iron became cheaper, and cultures learned how to make steel, which is stronger than bronze and holds a sharper edge longer.
Use of Bronze in Sculpture
Bronze can be superior to iron in many applications. It is considerably less brittle than iron. Bronze only oxidizes superficially; once the surface oxidizes, the thin oxide layer protects the underlying metal from further corrosion.
In the twentieth century, silicon was introduced as the primary alloying element, creating an alloy with wide application in industry and the major form used in contemporary statuary. Aluminium is also used for the structural metal aluminium bronze. It is also widely used for cast bronze sculpture. Many common bronze alloys have the unusual and very desirable property of expanding slightly just before they set, thus filling in the finest details of a mould. Bronze parts are tough and typically used for bearings, clips, electrical connectors and springs.
Indian Hindu artisans from the period of the Chola empire in Tamil Nadu, used bronze to create intricate statutes depicting the Gods of Hinduism mostly, but also the lifestyle of the period. In antiquity other cultures also produced works of high art using bronze. For example: in Africa the bronze heads of the Kingdom of Benin, in Europe; Grecian bronzes typically of figures from Greek mythology, in east Asia; Chinese bronzes of the Shang and Zhou dynasty - more often ceremonial vessels but including some figurine examples.
Bronze is the most popular metal for cast metal sculptures; a cast bronze sculpture is often called simply a "bronze". Common bronze alloys have the unusual and desirable property of expanding slightly just before they set, thus filling the finest details of a mould. Their strength and ductility (lack of brittleness) is an advantage when figures in action are to be created, especially when compared to various ceramic or stone materials. These qualities allow the creation of extended figures, or figures that have small cross sections in their support. Modern statuary bronze is 90% copper and 10% tin; older bronze alloys varied only slightly from this composition. But the value of the bronze for other uses is disadvantageous to the preservation of sculptures; few large ancient bronzes have survived, as many were melted down to make weapons in times of war or to create new sculptures commemorating the victors, while far more stone and ceramic works have come through the centuries, even if only in fragments.
The great civilizations of the old world worked in bronze for art, from the time of the introduction of the alloy for edged weapons. The Greeks were the first to scale the figures up to life size. Few examples exist in good condition; one is the seawater-preserved bronze now called "The Victorious Athlete," which required painstaking efforts to bring it to its present state for museum display. Far more Roman bronze statues have survived. The ancient Chinese, from at least 1200BC, knew both lost-wax casting and section mould casting, and in the Shang dynasty created large ritual vessels covered with complex decoration which have survived in tombs. Over the long creative period of Egyptian dynastic art, small lost-wax bronze figurines were made in large numbers; several thousand of them have been conserved in museum collections. From these beginnings, bronze art has continued to flourish.