Material Tests

A new porcelain and clay body

Markus Böhm has developed a new porcelain body especially for usage in wood fires. Of course I needed to do some material tests with this porcelain. The body is stable at 1300°C, is getting translucent and shows the pink color effects caused by the minimal iron oxide contamination. The results after a test firing were very promising.

A closer view of the results showed the weaknesses of the body. The shrinkage of the body does not fit to the shrinkage of the salt glaze. Tensions exist due to the “too-big” glaze and the glaze is chipping off. This can be seen at the rim of the cup. A closer look is possible when the cup is broken in pieces. The flakes can be chipped off the rim with a finger nail.
There Markus need to do some additional work.

I am always looking for new clay bodys that show nice colors when wood fired. Recently I found a body that contains almost 5% iron oxide and is stable up to 1300°C according to the data sheet. The firing color is stated as orange, but in a reductive environment the colors can be rather different. So, I put 2 sample cups into the next kiln.

The results are fantastic. Nice flame traces, a beautiful color, ash deposits, perfect. But only until you look at the top of the cup. The shape has deformed massively, therefore the data sheet is too positive. In a following experiment I will try to use the clay as a slip. Stay tuned…