I fired the kiln for the first time today. Zuimei had bought the kiln online for around $1200, and is a very large gas kiln. We had to get a crane to move it into place. Weighing in at 800 kg it was not easy to get into place and now it is unlikely it will ever move again.
Shortly after we got it moved into place the gas company came and hooked it up with 4 large gas cylinders. These are the same cylinders that most people here in Japan use in their homes. Because Japan has so many earthquakes running natural gas lines doesn’t make sense so they just have large propane tanks that get changed out. Our house uses 2 tanks for hot water and cooking. The kiln uses four.
I went out and using a BBQ starter I fired up one of the four burners. within seconds I heard something go *pop* and few seconds later again. I knew immediately what that sound was. It was ceramic bowls exploding. I made two mistakes:
The first was putting the work on the floor of the kiln. That puts it in direct contact with the fire which is not good. The second was I didn’t “candle” the kiln first. Candling is where you turn one burner on low and you leave the kiln door ajar for an hour or so. this drives any moisture out of the pieces before you start raining the temperature. Essentially what was happening in my kiln is I was boiling any water in the ceramic very quickly and it was popping like popcorn. Of course that causes shards of ceramic to fly about the kiln damaging other works as well. Figuring the damage had been done I left it and kept the firing going.
Originally I tried only using two canisters so I would have two to spare but when I left for 15 minutes to drop Zuimei off a the train station something went wrong. When I returned the flame was out and there was no pressure. It seems the tanks were empty. This makes me wonder if someone stole the canisters and replaced them with empty ones. It is quite possible since all the canisters look the same and the tanks are by the road. I will have to put up a camera nest time to see.
I turned every off again and left it to cool. Below is a photo of the damage. I would need to re-shelve everything, clean out the kiln and use all four canisters before I tried again.
That is the challenge with pottery. You have to live with a dragon and sometimes the dragon is kind, and sometimes… not so much.