Slip casting is a technique that is often used for the mass-production of pottery and other ceramics, especially for shapes not easily made on a wheel.
In slip casting, a liquid clay body (slip) is poured into plaster moulds and allowed to form a layer on the inside walls of the mould.
In a solid cast mould, ceramic objects such as handles and plates are surrounded by plaster on all sides with a reservoir for slip, and are removed when the solid piece is held within.
For a hollow cast mould, for objects such as vases and cups, once the plaster has absorbed most of the liquid from the outside layer of clay the remaining slip is poured off for later use. After a period for further absorption of water, the cast piece is removed from the mould once it is leather-hard, that is, firm enough to handle without losing its shape.
The item is then trimmed neatly and allowed to dry out further, usually overnight or for several hours. Once dry it can be bisque fired, then decorated / glazed and then a final firing in the kiln.
I enjoy the variety of items that can be produced using slip casting but often feel its cheating and prefer the feel of the clay in my hands using the potters wheel. There is however a place for slip casting and I am currently using this method for honey pots, jam pots and some tall jugs / hot chocolate drinking mugs.
“May your hands be full of clay and your hearts full of imagination” – Chrysalis Pottery