A pottery kiln, which is also referred to as a ceramic kiln, is a chamber that is used to harden pottery by heating it at a high temperatures. There are a specific types of kilns that are used for many different purposes. Depending on their type, kilns can be used to cure recently felled lumber, turn wood into charcoal, dry food products, and cremate human or animal remains. Pottery kilns, however, are used specifically for the purpose of manufacturing ceramics.
Pottery kilns are still used today by manufacturers as well as independent artisans. Modern kilns have become quite sophisticated and can be calibrated to meet very specific firing temperatures. We know, however, that pottery kilns have been used in one form or another for thousands of years. Of course, the first kilns were much cruder that those available today. These ancient kilns were simply made of large holes in the earth in which a large fire was built. Pottery was then placed inside of the fire for curing. Freestanding kilns with chimneys and other forms of controlling temperature and the finished product came later.
In pottery kilns, high temperatures are applied to the formed pottery clay. This heat permanently alters the chemical makeup of the clay so that it takes a permanent shape that can only be altered by breaking the finished product. The final look of a piece of fired pottery is dependent on the molding that the potter applied to the clay before placing it in the pottery kiln, any glazes that are applied to it, and the temperature within the kiln. Depending on the type of clay that is used, the application of any glazes, and the heat within the kiln, pottery can have a number of different type of finished looks. When pottery is placed in pottery kilns for heating, it is known as “firing” the pottery.
Unfired clay is a very malleable substance. The actual particles of clay are porous and very fine. When pottery is fired in a kiln, the particles melt together, creating a stronger substance that is less porous. The fact, the actual clay material shrinks slightly in size when it is fired. Although fired clay is much stronger than the raw substance, it is generally formed into rather large, thick objects because it is somewhat brittle. Most sturdy pottery, such as vases and dishes, is rather heavy. There are many types of pottery kilns, but the basic principles of firing clay remains the same in all of them.