What Is Pottery Clay?

Working with pottery clay is a popular hobby, enjoyed by all ages. Pottery clay is often introduced to children in art classes, sometimes leading to lifetime hobbies and careers. When first experimenting with clay, many people don't realize there are many different clays they can use to create pottery. Rather than select just any clay, it's important to know which clay is best for the pottery you wish to create.

Identification

A moist clay ready for sculpting or pottery wheels, pottery clay is made from fine-grained mixtures of hydrous silicate particles. Pottery clay is formed by chemical weathering and hydrothermal activity. Defined by geologists by the grain size, pottery clay is also characterized by the content. Although clay is plastic when wet, it dries firm.

Function

Pottery clay is used for making pottery that has various uses. Besides used as decorative art pieces, clay pottery is also used to make practical household items such vases, planters and kitchenware including jugs, pitchers, mixing bowls, tableware, goblets, mugs, napkin rings, plates, dishes, saucers and teapots. What's more, it's used to make candle holders, sculpture, lamps, tiles and jewelry. Other uses include making musical instruments, toys and architectural items, such as bricks and fireplaces.

Earthenware Pottery Clay

The three main types of pottery clay include earthenware, stoneware and porcelain. Each type is characterized by its clay mixture and the temperature needed to bake or fire it. An earthenware pottery clay mixture needs a lower temperature for firing for yielding colorful glazes. However, it also produces pottery that's more prone to crack and chip than stoneware or porcelain clay. Earthenware typically has a brown, buff or red color, depending on the color of clay used to make it. Although it's not as strong as stoneware, earthenware is porous. Terracotta is the name of earthenware pottery that's made from red clay. Earthenware is glazed and is usually used for liquids and for cooking in microwave ovens.

Stoneware Pottery Clay

Stoneware pottery clay, which is composed of a heavier clay mixture, yields a greater strength and is fired at a significantly higher temperature, giving a harder finish. This clay is generally not translucent. Stoneware clay should be heated between 2,100 and 2,300 degrees F for making pottery. Colors from stoneware pottery range from light or dark gray or light to dark brown. Stoneware pottery clay is mostly used for making dinnerware and jugs.

Porcelain Pottery Clay

The purest clay is porcelain, which is formed and fired at a temperature up to 2,550 degrees F. It's made from white clay called kaolin and is mixed with feldspar and flint. Kaolin clay easily breaks in its raw state, as the particles aren't as worn as with earthenware. Smooth and shiny, Kaolin clay is used for making fine china and porcelain pottery.

Considerations

Choosing the right pottery depends on the technical needs available for firing and your artistic skills. You'll need to know the temperature needed for firing and whether you have a kiln that can meet the requirements. Also, consider the color of pottery clay and the use of the pottery.

History

Pottery clay dates from 6000 B.C., when pottery was just a clump of clay that wasn't fired. Around 3000 B.C. (Bronze Age), the potter's wheel was introduced. However, by then the slow wheel was basically replaced in both Asia and Europe by the fast wheel, which could spin on an axle. During the Roman Empire, people started painting pottery red. Potters began making porcelain pitchers and cups around 700 A.D. as pottery grew popular in West Asia and China. However, it was quite expensive because it had to be transported from China on backs of camels and donkeys. Around 1200 A.D., various color glazes were used by Chinese potters. Later, West Asian potters started using their own colored glazes in imitation of Chinese designs, and Europeans use their own glazes, copying designs of West Asians.

Resources

• Types of Pottery