Salt glazing is a technique used by stoneware potters to create the glassy surface. When the pottery kiln reached over 2000 degrees Fahrenheit, salt was introduced to the kiln, creating a vapor. This vapor adhered to the silica in the clay, forming a glass. From the high temperature, the clay is often non-porous, or vitrified. This, combined with the salt glazing, allowed the potters to 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 (1782-1847) produced both earthenware and stoneware, although he is best known for his stoneware. Scholar H.E. Comstock notes that Keister was likely born in Virginia, but it is not known where he trained to become a potter. Keister is the first 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 paid in stoneware produced by himself. Adam Keister had seven sons who, with the exception of possibly one, all made pottery.
Comstock, H.E. The Pottery of the Shenandoah Valley Region. Winston-Salem, NC: Frank L. Horton Book Series, MESDA, 1994.