From the earliest known product, stoneware made in the Catawba Valley has been alkaline glazed. Alkaline glazes are made by combining hardwood ash or crushed glass with clay and water. Alkaline glazed stoneware takes on a brown or green color once fired in the
kiln. Catawba Valley potters chose alkaline glazes over salt glaze, the predominant stoneware glaze used in America at the time. Potters enjoyed an abundance of wood ash from burning their kilns while salt deposits were not very plentiful in the Carolinas. Furthermore, salt was especially expensive during and after the Civil War. The alkaline glazed ware was initially fired in what are known as "
groundhog kilns". These kilns were a unique southern U.S. variation of climbing kilns built into hillsides, such as the Asian
anagama. Semi-subterranean in construction, the groundhog kiln featured a door leading into a long, low passage of brick or rock construction, with a stack or chimney poking out of the ground uphill. Ware was loaded in the low passageway or "ware-bed" and the fire was built in a sunken firebox located just inside the door. The design allowed the stack to draw heated air, flames, and ash through the pottery grouped inside and created the draft needed to generate the intense heat required to create stoneware. This type of firing or "burning" worked particularly well with large pieces of pottery. Variations of these kilns, usually referred to as "tunnel kilns," are used by modern potters in Catawba Valley and other pottery regions in the American southeast. == Modern Potters from the Region ==