Monday, March 15, 2010

Pictures and my Thoughts on this Firing




Overall, I think it was a good firing. I glazed a few pieces with an alberta slip glaze that showed the effects of ash well, and I think I'll use the same glaze next firing on some larger pieces. I like simple glazes. I also mixed up a new batch of a glaze I made last time I fired: equal parts apple ash, rock dust and local clay. I glazed a tree bowl with this and it looked beautiful - until I looked inside. The tip of my thermocouple broke off and fell inside. The two large tree platters - one a white clay and one a darker clay - turned out nice, but the darker one had a crack in the rim. There wasn't as much ash buildup as I wanted, though.

I'm not sure about the use of my iron-rich local clay. Firing it to cone 12 or 13 causes bloating. At lower temperatures, it turns deep purple/black and has a dry surface which absorbs oil from my fingers. I didn't get all of Levi's clay tests in, but when using the local clay in combination with Loafer's Glory or Star White gives some interesting results.

I'll be taking some individual shots later in the week, and will share them then.

I feel like this firing took too long to reach temperature. Next time, I'll be trying to reach temperature quicker and soaking for a longer time. The designer of this kiln suggests stoking heavy every 10 minutes. I think we spent too much time finessing the fire this time. We lost a 200 degrees after reaching 2,200 degrees F. (around the time we pulled a pot out) and spent a couple of hours getting it back up to 2,200 again, tweaking the passive dampers and air intakes. After we reached 2,200 again, we stoked with just pine, leaner stokes more often and the kiln took off again. We reached cone 12 in the front and decided to keep stoking until we reached 10 toward the back. After we unloaded, we actually found we reached cone 11 on the back of the middle stack of shelves. We had to rake coals out several times during the last hour or more.

I'm new at firing with wood, so if there are any potters reading who would like to make suggestions or comments, please do.

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