Expert: Sam Kelly - 3/4/2009

Question
I am involved in an entrepreneurial venture involving ceramics and I'm seeking some technical advice.

Can cassius basaltic clay be made into a slip?

What is the optimum way to achieve the deepest (no hint of brown) black with very high gloss?
Suggestions for the appropriate glaze and cone sought.

Appreciatively,
Luca


Answer
Hi Luca, any clay can be turned into a slip. Cut the wet clay up into small pieces and let it dry out completely. Put the dry pieces in a container and add water until it just covers the dry clay. let it sit, do not stir, you will be able to see the clay disintegrating as it absorbs the water. Within a few hours it will be ready, next day is better, mix up and use.

Clear gloss glaze, fire to cone 4 first. If this is not the effect you want fire higher but not higher than cone 6. Fire in oxidation. Experiment with different clear gloss glazes.

All processes of clay and glazing are experimental until the desired result is found. What works for someone else may not work for you because of the amount of variables a potter can stumble across. Even kiln to kiln will give differing results at times, especially if it's a gas kiln.

Sam