Hello potters, it's fall and right on queue we had our first pumpkin explosion in the kiln :)

There's a lot of mystery surrounding the question of why pots explode in the kiln and I have an opinion on the matter. By and large, air bubbles play very little role in pot explosions. The vast majority of the time, it's due to water still trapped in a pot upon firing (usually because of thick walls).

However, sealed air pockets can create a pot explosion if the bubble is large enough and walls are thin enough. This only comes into play when we're intentionally creating closed forms like pumpkins, ornaments, etc. In terms of scale, I think a golf ball sized, sealed clay object with .5" walls is unlikely to explode from the trapped air. An orange sized, sealed clay object with .25" walls probably would explode.

Regardless, there's no sense in risking anything, so when you're making pumpkins this season, be mindful of extra thick bottoms or walls, and make sure to poke a hole somewhere so the air can escape during firing. The hole can be very small, but if you're putting it on the bottom of the pot, make sure it won't get resealed via clay smudge when the pot gets moved.

Pot on,

Ned