Terracotta is a clay-like earthenware ceramic that can be either glazed or unglazed. In addition to being used for flower pots, terracotta is also often used for water and sewage pipes, bricks and sculptures. The word “terracotta” comes from the Italian words for “baked earth.” Terracotta is often used as a colour word, too, to describe the natural brown-orange colour of terracotta products.
Terracotta can be easily sculpted into all sorts of shapes. To harden terracotta it must be heated to between 1,000-2,000° F. Once it hardens, it is still a bit porous, which means it can be penetrated by water. However, a simple coat of glaze can make terracotta water tight. Terracotta has been around for a long, long time. In fact, it was the only clay product used until around the 14th century. Archeologists have found terracotta sculptures that are approximately 5,000 years old.
Perhaps one of the most spectacular terracotta creations ever is the famous Terracotta Army. Also known as the Terracotta Warriors and Horses, the Terracotta Army is a massive collection of terracotta sculptures that represent the armies of Qin Shi Huang, the first Emperor of China.
The Terracotta Army was discovered in 1974 by local farmers in China. It consists of over 8,000 soldiers, 130 chariots, 520 horses and 150 cavalry horses buried in three large pits. This “army” was buried with the emperor around 210 B.C. The emperor believed his Terracotta Army would protect him in the afterlife and be a group of people he could continue to rule over.
It took skilled artists many years to make the Terracotta Army. Although many parts of the sculptures were mass-produced in workshops, each piece was finished with intricate facial features, weapons according to rank and bright paint. The life-sized soldiers of the Terracotta Army vary in height, uniform and hairstyle according to their rank in the army. The members of the army were placed in pits in such a way as to defend the emperor's tomb from the people to the east that he had previously conquered.
Production and properties
An appropriate refined clay is formed to the desired shape. After drying it is placed in a kiln or atop combustible material in a pit, and then fired. The typical firing temperature is around 1,000°C (1,830°F), though it may be as low as 600°C (1,112°F) in historic and archaeological examples. The iron content, reacting with oxygen during firing, gives the fired body a reddish colour, though the overall colour varies widely across shades of yellow, orange, buff, red, “terracotta”, pink, grey or brown. In some contexts, such as Roman figurines, white-coloured terracotta is known as pipeclay, as such clays were later preferred for tobacco pipes, normally made of clay until the 19th century.
Fired terracotta is not watertight, but surface-burnishing the body before firing can decrease its porousness and a layer of glaze can make it watertight. It is suitable for use below ground to carry pressurized water (an archaic use), for garden pots or building decoration in many environments, and for oil containers, oil lamps, or ovens. Most other uses, such as for tableware, sanitary piping, or building decoration in freezing environments, require the material to be glazed. Terracotta, if uncracked, will ring if lightly struck.
Painted (“polychrome”) terracotta is typically first covered with a thin coat of gesso, then painted. It has been very widely used but the paint is only suitable for indoor positions and is much less durable than fired colours in or under a ceramic glaze. Terracotta sculpture was very rarely left in its “raw” fired state in the West until the 18th century.