Traditional wisdom says that a porcelain body must be aged for months or even years before it can be used. This piece shows that it is not always the case.
For CHH, only 5 days elapsed between the body being mixed from powdered ingredients and the piece being thrown on the wheel, bisc and then glaze fired.
Good mixing is essential
CHH is made from my TP021 (Throwing Porcelain #21), a cone 10 body formulated using Puraflo 50 as the kaolin, bentonite and ball clay as the plasticisers and fluxed with a potash feldspar. Powerful mixing of the bentonite and ball clay is essential to disperse the fine particles and thoroughly wet them. I add these initially to the water and mix for 4 hours with a powerful paddle mixer (the same process I use for mixing casting slip). The kaolin is added next and mixed for another hour. Finally the feldspar and silica are added resulting in a thick mass that is initially hard to mix. After another 2 hours of mixing, the slip has thinned dramatically and is ready to be sieved and poured onto a plaster batt for dewatering.
I have also made this body by mixing the powders together with only sufficient water for plasticity and then kneading. The result is initially awful: a body that lacks plasticity and cannot be thrown on the wheel. It takes several months for the body to mature after which it gives good performance.
The first time I took the dewatered slip and kneaded it for throwing, I knew immediately that there was a major difference – plasticity was excellent immediately, months of waiting were not required.