Salt glazing was a technique used by stoneware potters to create a glassy surface. When the pottery kiln reached over 2000 degrees Fahrenheit, salt was introduced into the kiln, creating a vapor. This vapor adhered to the silica in the clay, forming a glassy appearance on the pottery. Because of the the high temperature at which the pottery was fired, the clay often became non-porous, or vitrified. This, combined with the salt glazing, meant that potters did not have to apply a glaze to the interior of the vessel. It could hold liquids and not seep, unlike earthenware storage vessels.
MAKER: Over the course of his potting career, Adam Keister (1782-1857) produced both earthenware and stoneware, though he is best known for his stoneware. Scholar H.E. Comstock notes that Keister was likely born in Virginia, but that the master potter he trained under is unknown. Keister is the earliest documented stoneware potter working in the Shenandoah Valley. An 1823 court record between Keister and a joiner who was to do work for him stated that Keister’s payment to the joiner was to be stoneware produced by him, Keister. Adam Keister had seven sons who, with the exception of possibly one, were potters.
Comstock, H. E. “The Pottery of the Shenandoah Valley Region.” Chapel Hill, NC: UNC Press, 1994.