25 June 2011

jiggering and piercing

Ceramic plates, bowls and similar items are shaped using a technique known as jiggering (or jolleying if the mold is in contact with the outside surface of the part rather than the inside surface). Although these processes can be automated, they are still frequently carried out by hand and require a skilled craftsman.

A charge of clay is placed onto a single-sided mould. As it rotates at high speed, the backside (jiggering) or inside (jolleying) are formed with a profiled tool. Parts made in this way must be rotationally symmetrical, but the patterns and decorations are moulded into the surface and so can be asymmetrical. After forming and a short time air drying, the holes are pierced using a profiled punch. 

Image from The Manufacturing Guides