terracotta

terracotta (It.: ‘baked earth’). Clay baked to become hard and compact. Since very early times it has been used to make figures and architectural ornaments, and it is to these, rather than pottery vessels, that the word ‘terracotta’ usually refers. Clay is found all over the world in many different colours and qualities. Coloured clay is commoner than white. The presence of certain chemicals, such as iron oxide, affects the colour of the baked product, so terracotta works are not necessarily of the reddish-brown colour that is normally associated with the word. Firing may produce a wide range of colour from light buff to deep red or black. The hardness and strength of the baked clay vary according to the temperature at which it has been fired. During the firing the clay shrinks by about one-tenth of its volume, sometimes more, sometimes less, according to its quality and the amount of moisture.