Glaze Testing with New Clay

Since the last post I have been continuing with tests. This time I have been focused more on seeing how some of the shop glazes react with the dark clay underneath. I did have some with dunting issues but I have a hunch that it was partially because of a glaze fit issue and less of the clay its self. This is because every glaze has a different coefficient of thermal expansion. Meaning every glaze imparts a different amount of stress on the clay. Some have better fit than others. Regardless below are some of the glaze tests. I have done some aggressive thermal shock tests. I poured in boiling water, let them heat up for about ten to twenty seconds. As they heated I was running cold water (to ensure it was as cold as the faucet could get). I poured out the boiling water and immediately dunked it under the cold water for another twenty or so seconds to really cool them quickly. The pictures below are the bowls that passed.

From left to right:

- Newly mixed “butter” glaze. Much whiter than I had imagined it being hence the name. I really do love the light and dark contrast from the clay and glaze. I will be experimenting much more with it to see how I can alter the results.

- My satin white glaze as a liner with Bennington, VT wild kaolin on the outside. I was surprised that my glaze is actually crazing a bit with this improved clay recipe. I will make alterations in order to make it fit well again.

- “Oatmeal” glaze. I am interested in the warmth of this glaze as well as the lovely matte surface.

- Celadon glaze. Not too interested in this color pallet but still useful information.

- Again my satin glaze in a hot and slightly oxidized section of the kiln. One major issue I am having is how sensitive my glaze is. You can see it is practically a clear glaze with some minor crystal formation. What I really need is a reliable glaze that is stable for mostly anywhere I put it in the kiln. I don’t mind a little variation but a satin white to almost a clear is a bit too much.