from The New Book of Knowledge®
Pottery consists of objects made from wet clay that are baked or fired so they will hold their shape. The term "pottery" usually refers to vessels, or containers. But it can also include sculptures. (Another term, "ceramics," includes a wide range of materials and products, such as bricks, cement, and electrical insulators as well as pottery.)
People have made pottery for thousands of years. Pottery vessels have been used for cooking, storing, and serving food. They have also been used as lamps and even as burial containers. In some societies, women were responsible for making pottery. In others, the potters were mainly men. More recently, men and women have shared equally in the making of pottery.
How Pottery Is Made
Pottery is traditionally made by hand. It must be formed into the desired shape, decorated, and then fired.
In one of the simplest techniques, clay is rolled into coils. The coils are built up layer by layer into the desired shape and then smoothed with a scraper or paddle. In a similar method, clay is shaped into flat slabs that are joined together while still wet.
Slabs of clay can also be formed by pressing them over a mold. In a process known as slipcasting, liquid clay, or "slip," is poured into molds to form various shapes.
Another method of making pottery is known as throwing. In this method, wet clay is placed in the center of a round table called a potter's wheel. As the wheel spins, the potter shapes the clay with his or her hands. This method gives the potter much greater control over the shape of the piece.
Pottery can be decorated in a number of ways. Designs can be pressed into the wet clay. Or they can be incised (scratched) onto the surface. Decorating with slip is also popular. In another technique, slip of one color is applied to a piece of pottery of a different color. Then designs are created by scratching away portions of the slip to expose the underlying color.
Glazing. One of the most common forms of pottery decoration is glazing. A glaze is a mixture of powdered minerals or glass and water that is applied to the surface of a piece of pottery. After application, the piece of pottery is fired again. The glaze becomes hard and glassy. This waterproofs the piece and gives it a colorful, smooth surface. There are many different kinds of glazes. Examples include celadon (a pale grayish green glaze), ash glaze (usually made of ground wood ash), and chun (a pale blue glaze used on stoneware).
Any kind of colored decoration applied to a piece of pottery before it is glazed is called an underglaze. An overglaze, or enamel, is any kind of colored decoration that is applied after a piece of pottery has been glazed and fired. After an overglaze is applied, the piece must be fired again (usually at a lower temperature).
Pottery is fired in a special oven called a kiln. Firing changes the nature of the clay. It makes it hard and durable. Most glazed pottery is fired twice, first to harden the clay body and then again after glazing. Firing temperatures depend on the kind of clay and decoration used.
Kinds of Pottery
There are three kinds of pottery: earthenware, stoneware, and porcelain. Some cultures have produced only earthenware. Other cultures have produced all three kinds at the same time.
To make earthenware, clay is dug straight from the earth, formed while still wet, and then fired at a low temperature—below 2200°F (1200°C). Sometimes earthenware bricks are baked in the sun. The color of earthenware varies depending on the clay used to make it. Colors after firing range from reds and yellows to white, gray, or black. Because earthenware is porous (not watertight), it is often glazed. Earthenware sculpture is sometimes referred to as terra-cotta.
Stoneware is made from special clays sometimes mixed with other materials, such as ground stone, and fired at a high temperature—about 2200°F (1200°C). As a result of this process, stoneware is made waterproof. The color of the clay after firing is usually gray or brown.
Porcelain is made from a special white clay, called kaolin. The kaolin is mixed with a powdered rock and fired at a very high temperature—2400°F (1300°C). Porcelain is hard, white, and translucent (light can be seen through it).
The Development of Pottery
Clay pots and other pottery pieces are among the oldest artifacts found at sites once occupied by ancient peoples. They provide archaeologists with a valuable record of daily life in these early cultures.
Earthenware was the first kind of pottery to be developed. It emerged in various cultures worldwide between 5000 and 3000 B.C. But archaeological evidence indicates that the first pottery may have been created even earlier—some 30,000 years ago.
Several theories have been suggested to explain the origins of pottery. The basketweave pattern found on some early pieces led to speculation that a layer of wet clay may have been pressed inside baskets to seal them. It may have been discovered that if the piece was placed in a fire, the basket would burn away and the clay would harden into a durable container. Another theory is that clay may have been used to line early fire pits, resulting in the formation of a simple pot that remained after the fire was put out.
Exact dates are impossible to determine. But it is thought that the first glazes were developed about 3500 B.C., probably in Egypt. And by 2500 B.C., the potter's wheel was being used in Egypt, Mesopotamia, and China.
It is sometimes said that everything we know today about pottery was already known by the 1300's in China. Whether or not this is true, China has one of the oldest continuous ceramic traditions in the world. The Chinese were among the earliest users of the potter's wheel. They are also credited with the invention of porcelain. So great is the Chinese contribution to ceramics that "china" has become the common term for many types of pottery.
All of China's early pottery was made to serve a useful purpose. But it did not all look the same. Some Early Neolithic (New Stone Age) pottery consisted of hand-formed painted pieces (Yangshao culture, 5000-300 B.C.) that had geometric and figural patterns colored by iron and manganese. Others were eggshell-thin black pottery (Longshan culture, from about 2500-2000 B.C.) thrown on a fast-moving wheel. The Chinese Neolithic potters seemed to be ahead of their time. They created deep cups with handles around 2000 B.C. that look like modern-day coffee mugs. This type of pottery was self-glazing. Its exterior surface looked as if it had been polished by hand.
Some of the most magnificent examples of early Chinese pottery are the thousands of life-size warriors and horses created to protect the tomb of Emperor Shi Huangdi against invaders in the afterlife. This terra-cotta pottery was created during the Qin dynasty (221-206 B.C.) and discovered in 1974. Each piece was originally decorated in vivid red, yellow, and blue pigments. But these colors have almost completely faded over time. The Chinese practice of placing pottery tomb figurines underground with the deceased reached its peak in the Tang dynasty (A.D. 618-906).
True porcelain had been created in China by the time of the Tang dynasty, and probably as early as the Sui dynasty (A.D. 581-618). The name "porcelain" is said to have come from Marco Polo. He compared the ceramics he found in China in the 1200's to a delicate seashell called porcellana in Italian.
Some of the porcelain from the Yuan, Ming, and Qing dynasties (A.D. 1260-1912) was produced on assembly lines made up of dozens of craftspeople who assisted with each specialized portion of a piece. One person might have been expert in painting floral designs. Another may have applied overglaze decoration. The porcelain from this period is famous for its beautiful decoration. Sometimes a deep cobalt blue or copper red underglaze was used. Other times, brilliant-colored overglazes were applied. These traditions continue today in China.
In the glazes that covered their pottery, Chinese potters also sought to duplicate the beauty of jade. Jade is a precious gemstone often carved into exquisite forms. During the Five Dynasties period (A.D. 907-960), celadon glazes were developed. They were perfected during the Song dynasty (960-1279). To give the pottery the surface texture of jade, the glaze was applied up to five times and refired to create the desired richness.
The pottery traditions of Japan were influenced by those of China. But the Japanese also developed their own distinctive styles. During Japan's Tumulus Period (A.D. 300-599), the Japanese placed hollow clay sculptures on the mounds that covered their royal tombs. These simple figures were known as haniwa. They were made of unglazed earthenware that turned a warm buff color when fired. They were made in the shapes of cylinders, shields, warriors, animals, houses, and other objects. They tell us much about daily life in Japan more than 1,500 years ago.
The Silk Road was an early trading route on which silk and other goods were transported. It connected the Islamic world (the Middle East, northern Africa, Spain, and Central Asia) to the Far East. It stretched some 5,000 miles (8,000 kilometers) across deserts, mountains, and grasslands from western Iran to northwest China. The communication among potters in these two regions was constant. The Chinese probably obtained the first good source of cobalt, used for underglaze decoration, from the Islamic world. They likely also borrowed and adapted the shapes of many decorative objects crafted in metal into Chinese earthenware funerary forms. Both of these cultures used brilliant lead glazes during the A.D. 700's.
One of the remarkable creations of Islamic potters was the use of luster as a decorative feature on their tin-glazed earthenwares. This began in the 800's in Iraq. (Tin glaze is a white, opaque glaze made with tin oxide.) These lusterwares were produced by painting special chemicals containing gold, silver, or copper onto the surfaces of the pottery. The pieces were baked in a fire with little oxygen to give the glazes a metallic sheen. Among the most breathtaking contributions of the Islamic world are the ceramics created in Iznik (Nicaea) during the peak of the Ottoman Empire in the 1500's. (Iznik was an ancient city in Turkey). A clear white body forms the background for bright blue, green, and red motifs that adorn dishes, mosque lamps, tankards (tall drinking vessels), and tiles.
The Greeks did not use glazes on their pottery. In the 500's and 400's B.C., they painted their polished pottery with figures and scenes using black slip on red earthenware (black-figure pottery). Later, they painted the background and some details with black slip, leaving the figures the color of the clay (red-figure pottery). This type of pottery is called Painted Attic (having characteristics common to ancient Athens). Typical designs include scenes from mythology, history, and daily life. The Greeks were among the earliest potters to sign their work, beginning around 530 to 330 B.C. And they often included inscriptions as part of the decoration. In Athens the potter owned and operated the kiln and employed several vase painters to decorate the pottery.
Some of the finest pottery sculpture of all time originated in Africa. By about 500 B.C., sculptors in the area of northern Nigeria created terra-cotta figures. These figures are considered the earliest preserved examples of sub-Saharan African sculpture known today. Terra-cotta heads and figures survive today from sites of the Nok culture. The Nok culture lasted from 900 B.C. to A.D. 200. The pottery remains show human forms with elaborate hairstyles, facial features, and body ornaments. Ghana's Akan culture, whose potters were highly trained professional women, often depicted deceased royalty. Graceful terra-cotta figures were created between A.D. 1000 and 1200 in Djenné, located in present-day Mali. They provide some of the only documentation of these peoples' lives.
Pottery in the Americas
Pottery exists from pre-Columbian America (America before the arrival of Columbus). It is remarkable because the people never developed stoneware, porcelain, glazes, or the potter's wheel. And their kiln technology was limited. The earthenware, hand-formed, and slip-decorated pottery of this region was created between 2000 B.C. and the A.D. 1500's by such cultures as the Remojadas, Olmec, Maya, and others. It is some of the most beautiful and imaginative in the world.
The most successful cultures were those of Mesoamerica (the land from central Mexico down to northwest Costa Rica) and Peru. Life-size figures, referred to as "babies," were made by the Olmec peoples of Mexico between the 1100's and 800's B.C. The figures were hollow and often constructed of white clay. They depicted entire human infant forms.
The earliest Native American pottery in North America dates from about 2,000 years ago. These fragile pieces were made by women for practical purposes. They are decorated with fine line-drawings or matte-black designs on polished black backgrounds.
Europeans greatly admired Chinese porcelain. It began appearing in the West through trade during the Middle Ages (A.D. 500-1500). But for centuries they did not know how to make it. Several different kinds of tin-glazed earthenwares were created that mimicked porcelain's white surface.
During the 1500's in Italy, potters created brightly decorated tin-glazed earthenware known as majolica. Their pottery style was referred to as istoriato, or narrative style, majolica. The pottery's white surface was used the way a painter uses a blank canvas. Pieces were decorated with portraits and images borrowed from the Bible and classical mythology. Works by famous artists such as Dürer and Raphael were also copied onto the pottery. The most important aspect of the piece was no longer its form but rather the images covering its form. At this time in Italy, pottery was considered nearly a fine art.
Other tin-glazed earthenwares created in Europe included France's faience. Faience was named after the Italian town of Faenza where the first examples came from. The Netherlands' delftware was named for the town of Delft where much of it was made.
Attempts to create true porcelain in Europe during the late 1500's resulted in the discovery of what is referred to as soft-paste porcelain. Soft-paste porcelain lacks the hardness of true porcelain due to its composition of clay and ground glass. The secret of true, or hard-paste, porcelain was finally discovered in Europe in 1709-10 by the alchemist Johann Friedrich B