Moulded hollow parts, e.g. jugs and tureens, are "cast" from a liquid porcelain mass - the slip - in plaster moulds. This process is called hollow casting or hollow part production, because the porcelain mass introduced does not completely harden into a solid. Porcelain makers call the bodies produced using the moulding process "cast items".

 

After a short standing time, the plaster mould begins to extract the water from the porcelain mass. The mass solidifies on the walls of the plaster mould until the raw article has reached its wall thickness after a predetermined time. The remaining mass is simply tipped out and used for the next production cycle. The most common production systems are casting benches, casting moulds or casting lines.

 

From a craftsman's point of view, moulding is a demanding method of porcelain production. Once the mould shells have stood, they have to be opened and the soft porcelain body removed from the mould. This production step is particularly sensitive because the body is easily deformed. The body is still quite soft and a little finger pressure is enough to deform the item. According to particular experience and time values - also depending on the type of hollow body and the climatic conditions - the slip must remain in the plaster mould for between 3 and 20 minutes in order to bring the cast article into its final shape.

 

 

Despite state-of-the-art developments and constantly advancing technology, it has not yet been possible to replace this method of hollow body production with an automated process.

 

 

 

The solid casting process is mostly used for snouts and handles as well as for other solid attachments and decorations. Masses, moulds and the process are very similar to the hollow casting process and differ only in that the mass hardens completely in the mould and a relatively solid body is produced after shaping. Depending on the thickness of the cast item, the mass must harden in the mould for several hours before it can be opened and the item removed.