Pit Firing Process

On May 29th I tried pit firing ceramics for the first time down at the family farm. It was during an annual family celebration, so we made a thing of it. A few of the cleaned-up, waxed pieces can be seen in the next blog below.

Casting "shells" for pit firing. After sitting for a while, the plaster absorbs water from the slip. The longer it sits, the thicker the piece. The excess slip is then poured into a bucket. After some handwork to clean and smooth the pieces, they are left to dry and then fired in an electric kiln. This will prevent breaking during the eventual pit firing.
Slip casting shells – slip is just a liquid clay body formulated for casting. After sitting for a while, the plaster absorbs water from the slip. The longer it sits, the thicker the piece. The excess slip is then poured into a bucket. After some handwork to clean and smooth the pieces, they are left to dry and then fired in an electric kiln. This will prevent breaking during the eventual pit firing.
After all the hard work of digging the pit (I had massive help there; no way I could have gotten through all that ridiculous bedrock), it’s time to load the pit with various materials while a nephew supervises.
The bed of the pit has been lined with sawdust, newspaper and straw. Some of the straw had been previously soaked in salt brine and then dried. You can see that a few of the pieces have been wrapped in burlap (also soaked in salt and dried) and copper wire. Different chemicals and techniques have different results in term of color, so I’m just experimenting with different things.
Before filling up the pit with the rest of the filler materials, I spread a few chemicals around. Here I’m sprinkling red iron oxide – for reds obviously, copper carbonate for green, cobalt oxide for blue, and manganese dioxide for purple. Rock salt was sprinkeld throughout as well as my nephew tracks my progress.
Finally time to get the party started.
Everyone loves fire.
You let the fire burn out, and hope things go well as you have to wait overnight or longer until the work is cool enough to pull out. I was initially disappointed as we had a ventilation problem, but some pieces still came out really well after being cleaned up and polished. The next round of pit firing was immediately scheduled for July 4th so we could try a change in the design.

See this post for the initial results polished up: https://rmgardner.wordpress.com/2010/06/08/work-in-progress-results-of-1st-pit-firing/

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