clay

clay. A sticky, fine-grained earth, composed essentially of rock dust and water, that can be moulded and cut into shape; it has been used in most civilizations for practical purposes, notably for making bricks, tiles, and pottery, and to a lesser but still significant extent in sculpture and decoration. Clay suitable for use as a modelling material is found in virtually every part of the world, in many different colours and qualities. Coloured clay is commoner than white. For sculptural purposes, lighter-coloured earths are generally preferred, as they show workmanship more clearly. Clay is worked mainly with the fingers, although many different wooden and metal implements have been employed as secondary tools. Often clay sculpture is fired in a kiln to make it more permanent; the resultant material is called terracotta. Like wax, clay has been used a good deal for making preparatory models but also for finished works of sculpture, usually fairly small ones, such as portrait busts (because of its comparative fragility, it has seldom been used for large pieces, although the Etruscans, for example, made impressive life-sized terracotta figures). The surface is often left in its natural state, but it can also be painted and/or glazed; Luca della Robbia and his family made a speciality of coloured, glazed terracotta reliefs. See also bole.