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. Evidence on the pottery reveals the nature of stacking used inside of the kiln in order to fire the vessels. In firing a salt-glazed stoneware kiln, kiln furniture is necessary as a buffer between the pieces of pottery in order to keep the glass created by the salt firing from adhering the vessels to one another. Kiln furniture was often made with the same clay as the vessels, sometimes with additional grog or sand mixed in, and then rolled in sand in order to further protect the vessels. The Thomas churn has smaller shadows of pads used for kiln furniture on the base and the rim of the vessel. This means that the churn was stacked between two other pieces of pottery in the kiln.
MAKER: Isaac Thomas, born in 1790, married Sarah Ricketts, the daughter of an established Maysville potter, Rulef Ricketts. Most research states that Isaac Thomas did not begin his pottery manufacture until the early 1830s, however, Isaac Thomas witnesses a lease of land for Rulef Ricketts in 1806, implying that Thomas was in Maysville, and perhaps working with Ricketts, or at least a close relation. Isaac Thomas and his father David are both listed in the 1810 Census in Mason County, Kentucky (where Maysville is located). In the 1850 census of manufacture Isaac Thomas lists making 50,000 gallons of stoneware, using 250 cords wood, having 8 male workers, using $200 clay, $3,000 invested, and all at $4,500 profit. Isaac Thomas’ ability to create such a large amount of stoneware each year may rely on the fact that he owned slaves. Thomas’ 1850 census of manufacture lists 8 males as paid workers, and his slave schedule lists his ownership of 3 male slaves and 4 female slaves. The collective work of Isaac Thomas defies the argument that Southwestern Pennsylvania potters in the third quarter of the nineteenth-century were the first to greatly utilize and take advantage of river trade to New Orleans and other points south. Surviving pieces of pottery marked with the stamp “I. Thomas” and some marked with “Maysville” are found in Louisiana, as well as in Mississippi and Missouri. An intact one gallon crock stamped “I.Thomas” is stenciled with cobalt blue slip, “AL YEISER & CO/VICKSBURG” demonstrating that Isaac Thomas was making vessels for merchants as far as Vicksburg, Mississippi by the mid nineteenth-century.