I guess things had been humming along quite nicely over the last year as I'd finally found a clay that could withstand the stress and strain of drying and firing. There had been very few bonsai pots that had cracked during the firings.
However, over the last month there seems to have been a bit of an issue with my larger pots once again.
I'd fired 3 larger oval pots in the kiln last week. Because of their size it is difficult to add extra pieces to fill up the gaps in the kiln. As a result there is a bit of empty space inside and the kiln tends to cool down quicker than if its really full. Usually I pack small bits of shelf offcuts and kiln props into any empty area to hopefully hold a little more heat for longer. For some reason it didn't work this time!
This was the result