To prepare the plaster molds, they are covered with talc in powdered form (talcum). This prevents the porcelain to stick to the surface of the plaster.
The molds are each consisting of two parts. In this step they are put together with adjustable straps. The lock (fig. 10) built into the molds prevents displacement
Before the porcelain can be poured in, it has to be stirred up by hand until no air bubbles are rising up to the surface anymore and the porcelain feels nice and smooth. Afterwards stirring can go on for some minutes with a wooden stick.
The porcelain has to be strained before casting to prevent clumps or in this case bigger bone pieces from messing up the objects surface and stabilty.
Filling up the mold with porcelain. The mold has to be refilled continuously (the porcelain will shrink while drying).
Before the porcelain can be poured out, the mold has to be shaken for about one minute. This is to make the rest of the material fluid again to ensure a good pouring behaviour – resulting in a nice and even inner surface.
Pouring out the remaining porcelain while rotating the mold.
Let it dry inside the mold for several hours. Then you can seperate the porcelain object from the mold.
With a good quality plaster mold it is possible to recast up to 30 times.
Fig. 11 Treating the porcelain object, smoothing the surface
Fig. 12 Porcelain Urn (As exhibited at Temporary Gallery, Cologne)