Slip casting is making pottery by pouring liquid casting slip into a plaster mould. The plaster absorbs water, a clay wall builds up inside, and the extra slip is poured out, leaving a hollow piece that is removed once it firms.
What Is Slip Casting?
Slip casting is how most commercial mugs, figurines and tableware are made, and studio potters use it for repeatable forms and very thin, delicate pieces. The thickness of the wall depends on how long the slip stays in the mould before it is drained.
Good casting needs a well-made slip at the right specific gravity and flow, and dry moulds. The pour should be steady and the mould filled to the top, then topped up as the level drops. After draining, the cast firms up in the mould until it shrinks slightly away from the walls and can be released.
Seams from the mould joins are cleaned off at leather hard or bone dry, carefully, because cast pieces are thin and fragile. Wet cleaning keeps the dust down.
Bone china and porcelain are usually slip cast, because they are too short to throw easily. Commercial moulds are widely available, and making your own from a model is a satisfying next step.
This pottery glossary entry from Le Studio Art Space is general educational content. Always follow the clay, glaze and kiln makers’ data for your own materials and equipment.