Terracotta, Terra cotta or Terra-cotta (Italian: "baked earth", from the Latin terra cotta), a type of earthenware, is a clay-based unglazed or glazed ceramic, where the fired body is porous. Its uses include vessels (notably flower pots), water and waste water pipes, bricks, and surface embellishment in building construction, along with sculpture such as the Terracotta Army and Greek terracotta figurines. The term is also used to refer to items made out of this material and to its natural, brownish orange color, which varies considerably. In archaeology and art history, "terracotta" is often used of objects not made on a potter's wheel, such as figurines, where objects made on the wheel from the same material, possibly even by the same person, are called pottery; the choice of term depending on the type of object rather than the material
Production and properties
An appropriate refined clay is shaped into 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 1000°C. The iron content gives the fired body a yellow, orange, red, "terracotta", pink, grey or brown color. 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 in-ground use to carry pressurized water (an archaic use), for garden ware or building decoration in tropical 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 that the material be glazed. Terracotta, if uncracked, will ring if lightly struck. Some types of terracotta are created from body that includes recycled terracotta ("grog").
Terracotta was the only ceramic produced by Western and pre-Columbian people until the 14th century, when European higher fired stoneware began production. Terracotta has been used throughout history for sculpture and pottery, as well as bricks and roof shingles. In ancient times, the first clay sculptures were dried (baked) in the sun after being formed. Later, they were placed in the ashes of open hearths to harden, and finally kilns were used, similar to those used for pottery today. However only after firing to high temperature would it be classed as a ceramic material.
In art history
Terracotta female figurines* were uncovered by archaeologists in excavations of Mohenjo-daro (3000-1500 BC) in what is now Pakistan. Along with phallus-shaped stones, these suggest some sort of fertility cult and a belief in a mother goddess. The Burney Relief is an outstanding terracotta plaque from Ancient Mesopotamia of about 1950 BC.
The ancient Greeks Tanagra figurines are mass-produced mold-cast and fired terracotta figurines. Significant uses of terracotta have included Emperor Qin Shi Huang's Terracotta Army of China, built in 210–209 BC.
Precolonial West African sculpture also made extensive use of terracotta. The regions most recognized for producing terracotta art in this part of the world include the Nok culture of central and north-central Nigeria, the Ife/Benin cultural axis in western and southern Nigeria (also noted for its exceptionally naturalistic sculpture), and the Igbo culture area of eastern Nigeria, which excelled in terracotta pottery. These related, but separate, traditions also gave birth to elaborate schools of bronze and brass sculpture in the area.
French sculptor Albert-Ernest Carrier-Belleuse made many terracotta pieces, but possibly the most famous is The Abduction of Hippodameia depicting the Greek mythological scene of a centaur kidnapping Hippodameia on her wedding day. American architect Louis Sullivan is well known for his elaborate glazed terracotta ornamentation, designs that would have been impossible to execute in any other medium. Terracotta and tile were used extensively in the town buildings of Victorian Birmingham, England.
In chemistry, pieces of terracotta are used as a heterogeneous catalyst to "crack" long-chain alkanes. This process is useful for obtaining more useful products, such as gasoline or petrol, from less useful ones, such as highly viscous long chain alkanes.
Advantages in sculpture
As compared to bronze sculpture, terracotta uses a far simpler process for creating the finished work with much lower material costs. Reusable mold-making techniques may be used for series production. Compared to marble sculpture and other stonework the finished product is far lighter and may be further glazed to produce objects with color or durable simulations of metal patina. Robust durable works for outdoor use require greater thickness and so will be heavier, with more care needed in the drying of the unfinished piece to prevent cracking as the material shrinks. Structural considerations are similar to those required for stone sculpture.