University Collections of Art and History

Object Record

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Catalog Number 2013.6.1
Object Name Mold
Description Salt-glazed stoneware master or block mold for making slip-cast sauceboats. The thick, roughly oval mold has a spout at either end and is decorated with scallop shells molded in relief. On the interior is a pencil inscription "Mason."

Slip-casting was developed around 1740, and is a process by which elaborately shaped and molded objects are made by using slip, or liquid clay, and absorbent plaster-of-paris molds. The multi-step process begins by carving a positive model, which is then used to make a negative mold, from which a positive master mold (like this piece) is made of a durable material like salt-glazed stoneware. The master mold is then used to make negative working molds out of plaster-of-paris.

To make a vessel, the working mold is filled with slip. The water in the slip begins to absorb into the mold, leaving a skin of clay particles on the interior of the mold, much like a skin forms on gravy. Once the skin is thick enough, the excess slip is poured off, and the mold with its skin of clay is allowed to dry. As it dries, the clay shrinks, pulling away from the mold, which is then opened and the vessel removed and fired in a kiln.

Slip-casting did allow for large numbers of elaborately-decorated objects to be made uniformly by semi-skilled labor, but in the 18th century it was not an inexpensive process; the master molds were made by skilled sculptors and were expensive and the plaster-of-paris working molds took a long time to dry between use and wore out quickly. However, it was an increasingly utilized technique by potters looking to make elaborate wares that could command a premium among upper-middle and upper-class consumers.
Year Range from 1750
Year Range to 1760
Material Salt-Glazed Stoneware
Place of Origin Made in Staffordshire, England
Collection The Reeves Center
On View No