For a detailed description of how I've done pit firings in the past, see my blogs from April, 2013 and October, 2014.
I tried several new things this time. First, I tried pit firing one of my bowls. I mounded up the sawdust and put the bowl upside down on top of it. The inside developed a very interesting metallic finish while the outside had great color. Unfortunately someone decided to throw vermiculite (mixed with copper sulfate) directly on the bowl when the firing was almost finished. As a result, it left large rough patches. When I came to take my pots out the next day (after more than 20 hours in the barrel), the two vases were cool and could be easily picked up with my bare hands but the bowl was still very hot. I was in a hurry so I pulled it out and set it on a brick. It cooled too quickly and developed several cracks as it contracted so I had to throw it away. Next time I pit fire a bowl I'll have to make sure I give it enough time to completely cool in the barrel. Second, I roughened the surface of my tallest pot to see how it would look when pit fired. It certainly did give the piece a different look than one that's perfectly smooth, but I'm not sure if I like it or not. Third, I carved the side of a second bowl to see how texture would look in a pit firing, but someone knocked it off the table when we were getting ready to load and it broke on the ground. Guess I should have put it upside down on the table. Fourth, I sprayed three of the four pots with terra sig instead of brushing it on. It seemed to cover the pots well, but I had trouble getting any sort of sheen by buffing. I'll have to figure out what I was doing wrong. Fifth, I used a half barrel with higher sides than usual because I thought it would offer more protection from the wind. It seems to have offered too much protection. I didn't get enough air circulation so my fire never got going well and the pots seem dark and underfired. You can see where great color is on the pot, but it's lying under a layer of gray because the carbon wasn't burned off. Sixth, I tried using a few new things to give color to the pots. I added red iron oxide which may have contributed to the overly dark color of the pots. I also put copper wire on the bowl and the tallest pot and it left a few black lines, nothing spectacular. Seventh, I usually use fairly coarse sawdust at the bottom of the barrel, but this time I used a superfine sawdust from sanding. Several other people used the same sawdust as well, and none of us had pots that developed jet black sections, just alot of gray. I assumed the superfine sawdust would produce an even deeper black, but it didn't seem to work that way, at least not in this firing.
So overall I'm not too pleased with this pit firing, but I've learned a few things that I can take with me to the next firing. I also enjoyed making and eating pizza made in Steve Martin's pizza oven. That helped to make up for some of my frustrations!
I tried several new things this time. First, I tried pit firing one of my bowls. I mounded up the sawdust and put the bowl upside down on top of it. The inside developed a very interesting metallic finish while the outside had great color. Unfortunately someone decided to throw vermiculite (mixed with copper sulfate) directly on the bowl when the firing was almost finished. As a result, it left large rough patches. When I came to take my pots out the next day (after more than 20 hours in the barrel), the two vases were cool and could be easily picked up with my bare hands but the bowl was still very hot. I was in a hurry so I pulled it out and set it on a brick. It cooled too quickly and developed several cracks as it contracted so I had to throw it away. Next time I pit fire a bowl I'll have to make sure I give it enough time to completely cool in the barrel. Second, I roughened the surface of my tallest pot to see how it would look when pit fired. It certainly did give the piece a different look than one that's perfectly smooth, but I'm not sure if I like it or not. Third, I carved the side of a second bowl to see how texture would look in a pit firing, but someone knocked it off the table when we were getting ready to load and it broke on the ground. Guess I should have put it upside down on the table. Fourth, I sprayed three of the four pots with terra sig instead of brushing it on. It seemed to cover the pots well, but I had trouble getting any sort of sheen by buffing. I'll have to figure out what I was doing wrong. Fifth, I used a half barrel with higher sides than usual because I thought it would offer more protection from the wind. It seems to have offered too much protection. I didn't get enough air circulation so my fire never got going well and the pots seem dark and underfired. You can see where great color is on the pot, but it's lying under a layer of gray because the carbon wasn't burned off. Sixth, I tried using a few new things to give color to the pots. I added red iron oxide which may have contributed to the overly dark color of the pots. I also put copper wire on the bowl and the tallest pot and it left a few black lines, nothing spectacular. Seventh, I usually use fairly coarse sawdust at the bottom of the barrel, but this time I used a superfine sawdust from sanding. Several other people used the same sawdust as well, and none of us had pots that developed jet black sections, just alot of gray. I assumed the superfine sawdust would produce an even deeper black, but it didn't seem to work that way, at least not in this firing.
So overall I'm not too pleased with this pit firing, but I've learned a few things that I can take with me to the next firing. I also enjoyed making and eating pizza made in Steve Martin's pizza oven. That helped to make up for some of my frustrations!
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