With the invention of hollow casting bronze became the most important medium of monumental sculpture, largely because of its strength and lightness, which admitted poses that would not be possible in stone. But the value of the metal in later ages has involved the destruction of nearly all such statues. The few complete figures that survive, and a somewhat more numerous series of detached heads and portrait-busts, attest the excellence of ancient work in this material. The earliest statuettes are chiselled, wrought and welded; next in time come solid castings, but larger figures were composed of hammered sections, like domestic utensils, each part worked separately in repoussé and the whole assembled with rivets (σφυρήλατα). Very little of this flimsy fabric is extant, but chance has preserved one bust entire, in the Polledrara Tomb at Vulci. This belongs to the early 6th century BC, the age of repoussé work.
The process was soon superseded in such subjects by hollow casting, but beaten reliefs, the household craft from which Greek bronze work sprang, persisted in some special and highly perfected forms, as handle-plates on certain vases, emblemata on mirror-cases, and particularly as ornaments of armour, where light weight was required. The Siris bronzes in the British Museum are shoulder-pieces from a 4th-century cuirass. Casting was done by the cire perdue process in clay moulds, but a great deal of labour was spent on finishing. The casts are very finely chased, and most large pieces contain patches, inserted to make good the flaws. Heads and limbs of statues were cast separately and adjusted to the bodies: besides the evidence of literature and of the actual bronzes, there is an illustration of a dismembered statue in the making on a painted vase in Berlin.
Pliny and other ancient writers have much to say in regard to various alloys of bronze — Corinthian, Delian, Aeginetan, Syracusan — in regard to their composition and uses and particularly to their colour effects, but their statements have not been confirmed by modern analyses and are sometimes manifestly false. Corinthian bronze is said to have been first produced by accident in the Roman burning of the city (146 BC) when streams of molten copper, gold and silver mingled. Similar tales are told by Plutarch and Pliny about the artists' control of colour: Silanion made a pale-faced Jocasta by mixing silver with his bronze, Aristonidas made Athamas blush with an alloy of iron. There is good evidence that Greek and Roman bronzes were not artificially patinated, though many were gilt or silvered. Plutarch admires the blue colour of some very ancient statues at Delphi, and wonders how it was produced; Pliny mentions a bitumen wash, but this was doubtless a protective lacquer; and a 4th-century inscription from Chios records the regulations made there for keeping a public statue clean and bright.