American potters have “burned” their wares in a wide variety of kilns, or furnaces. The kiln shape is typically rectangular or round. The rectangular kiln is thought to be of German origin, but appears to have been the earliest type built in America at Jamestown, Virginia before 1640. Commonly called a “groundhog” kiln, this style spread throughout the South and was built into hillsides or partially underground.
An above-ground variant, called the “tunnel” kiln was also common in the South. All of these early kilns were wood-burning, but during the last half of the twentieth century many were adapted for use with coal, gas or electricity.
Most wood-fired rectangular kilns utilize a cross-draft where heat is pulled from a firebox at the front of the kiln to a chimney in the rear. The pottery is “burned” as the heat is pulled toward the chimney.
The “beehive” kiln is of English origin but was not introduced in the South until well after the Civil War. Unlike the cross-draft of a rectangular kiln, beehive kilns utilize an updraft or downdraft method of firing. Heat from fireboxes located around the perimeter of the kiln is either pulled upward through vents in the ceiling or drawn downward to a flue located below the level of the floor.
Downdraft beehive kilns were considered more efficient and more consistent in the production of evenly-fired pottery. Depending on the size and type of kiln, a firing might take as long as twenty hours. The kiln is usually left to cool for several days prior to opening and unloading. Only then will the potter know if a particular load was successful.