Potters & Sculptors - Making Rock from Mud
In a recent glaze firing at our community studio, something exploded and we wonder whether it might have been one or more of the bisqued "cookies" placed under a couple of pieces in case of possible glaze drips. These cookies have been used in multiple glaze firings - let's say perhaps 4 - 6, not sure. No thrown / glazed pieces blew up (as far as we know), though some were damaged, of course, from the bisque fragments embedded in them. Someone suggested clay fatigue as a possibility, saying that on occasion a ceramic baking dish used for some years can explode in the oven (and wouldn't THAT be a mess!).
Can anyone offer ideas about this? Thanks.
Neil Estrick said:
That Dogwood article is interesting. I think just opposite is actually true in regards to salt migration during fast drying. The slower it dries, the more likely you are to get salt migrating to the surface. We see this in carbon trap Shino glazes that have soda ash in them. If you want the slat to migrate to the surface for optimal carbon trapping, you have to dry them slowly, or at least at normal room temperature rates. Drying them in the kiln will not allow the salt to come to the surface.
If something blew up in the kiln, it was wet. Pieces that are fired too many times simply crack. They don't explode.