In this method the mould forms both the inner and outer face of the cast. This process is called drain casting because the moulds are emptied of excess slip. 7-A produces a hollow item which outside has the shape of the mould. Slip casting is a fairly new process in the history of ceramics, as it only became practical after the invention of plaster of parts 200 years ago.
The word 'slip' means a single clay or a mixture of clays and other materials that has been mixed with enough water to make it liquid, so that it can be poured into a plaster mould. Slip casting is a specialized way of using plaster moulds for mass production of ceramics.
