|Monthly Tech-Tip |
This cast bowl (just out of the mold and dried) is 130mm in diameter and 85mm deep and yet the walls are only 1mm thick and it only weighs 89 gm! The slip was in the mold for only 1 minute. What slip? A New Zealand Halloysite based cone 6 translucent porcelain. This NZ material is fabulous for casting slips (it needs a little extra plasticizer also to give the body the strength to pull away from the mold surface as it shrinks).
|Materials||New Zealand Halloysite|
Formulating a Porcelain
The principles behind formulating a porcelain are quite simple. You just need to know the purpose of each material, a starting recipe and a testing regimen.
The deflocculation process is the magic behind the ceramic casting process. It enables you to make a slurry of far lower water content and thus lower shrinkage.
A method of forming ceramics where a deflocculated (low water content) slurry is poured into absorbent plaster molds, forming a layer against mold walls, then poured out.