Yesterday I fired our new soda kiln at the potters guild with a group of friends from the guild. This was the first time that I had fired this kiln since it was rebuilt last summer. Thankfully there was one member of the team who had fired the kiln before and she at least had some experience with the kiln, although it sounds like it wasn't a good one. My friend said that the last time she fired the soda kiln the top was about two cones cooler than the bottom, which is enough that the glazes on the top did not mature. While we were loading she said that the designer and builder of the kiln had suggested building the bag wall up taller to try and draw more flame up to the top, but we decided not to try that this time. As I was starting up the kiln yesterday morning I found myself pondering this problem. I had been taught that removing the peep cover (or plug) in the cool area can help to draw the flame, and thus heat, through the cooler area, resulting in a more even firing. We decided to try this and, I have to say, I don't think I have ever fired such an even kiln. We left the top peep out of the kiln from about 2000 degrees until we added the soda to the kiln and when we shut the kiln down cone ten was at 3 o'clock on top and bottom. I can't wait until we unload on Tuesday to see how the firing went for sure, but the indications are that it went wonderfully and we should have some beautiful pots.
It's kind of cool to think that I now have the knowledge to be able to trouble shoot a kiln problem like this.
Or maybe this kiln goddess just likes me ;)
Here are some pictures from the firing.