Thermal Shock

There are a couple of worst case scenarios that haunt the dreams of potters. Studio fires, stacks of shelves collapsing mid-firing, arches failing, etc. Back in December we got to experience another one of these pottery nightmares—a kiln load full of cracking pots.
Our first impression of the work was good. When we wood fire, we aim to strike a balance between drama and subtlety, and these pots were definitely moving in the right direction. A few of our favorites immediately went into use for morning coffee, and all seemed well. However, we had an order of 12 mugs to ship out and decided to test them all with boiling water. This is a pretty ordinary test to make sure the ware can withstand thermal shock.
The first one shattered instantly upon being filled. No problem, we have plenty of extras…To our horror, one after the next then cracked in the same manner. After a certain point it became clear that all the mugs were likely compromised. We didn’t have the heart to keep testing them, so all the new cups went into a box where they remain today.
We then had the regrettable task of calling the customer who had placed the order to explain why we could not send out the mugs. Luckily they were understanding and gracious, but it was the kind of phone call that you never want to have to make.

The aftermath of a firing can always be a difficult time, as you manage the way your expectations measure up to the actual pots that come out of the kiln. This was something else however. After weeks of making pots, stacking wood, glazing, loading the kiln, and the huge effort of firing, we felt utterly defeated. To top it off, we really like some of these pots, and yet they can’t be sold.

It took some distance to see that this is a good problem for us. There are lots of questions. Why did everything crack? This is clay we’ve been using for awhile, so what went wrong? The answer lies partly in the firing and partly in our clay. Both of these questions will need to be addressed as we work towards not just our next firing, but towards gaining a greater understanding of our materials and processes in general. The problems we are having now will make us better potters, with better pots to offer to you all.