Thursday, July 22, 2010

Foot Bowls off Schedule?

In the post below, I said I had three bowls cooling in the kiln and another three glazed and ready to replace the ones cooling in the kiln. Well, I unloaded the three bowls and they all had cracked feet. They didn't blow up, which tells me it wasn't water in the clay turning to steam and blowing up the pots. So, why did this happen?

I didn't reload the kiln. I'm thinking maybe the fracture is developing because I'm loading green pots on hot shelves and the heat is fracturing the unfired clay early in the firing. I've been opening the kiln at 130 degrees F. and unloading when I can pick them up bare handed. I wonder if the shelves might be hotter than 130 degrees. Who knows? There are so many variables in the process, it's hard to figure it out. Just when I think I've got it figured out.

The bottom line is that I'm pushing these pots more than I would like to because of the deadline, and it's up to me to make the judgement of when I'm pushing too hard. I think I remember lifting the shelves when loading this kiln and thinking they might be too hot to handle.

Any potters have experience with this - unfired pots fracturing on hot shelves?
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