Wood firing kilns and processes

David in his wood fire kiln

​Many potters dream about having their own wood fired kiln, but what exactly goes on behind the scenes. We asked David Voorhees, one of our online teachers who has his own wood fire kiln in North Carolina to answer some of the most common questions about wood firing.  

• ​How long does it take to fire the kiln?
• How long does it take to pack and unpack the kiln?
• How much wood do you use?
• ​How long do you normally fire the kiln?

​​Every wood-fired kiln is different as they are all site built and of varying dimensions. Firing lengths can vary for effect as well with many potters reaching cone 10 or 2300F then holding it there for a day or more to accumulate melting wood ash. My kiln is pretty straight forward with a rise to cone 10, then spraying a few pounds of soda ash solution followed by slowly shutting it down as the last of the firebox wood gets consumed. My kiln holds about 250 pots and takes 26-28 hours to fire and 3 days to cool down. I usually have 3 to 6 potters join me with a few pots and some firing duties. Since it also a car kiln it is easy to load taking only two to three hours to load and get started. Unloading takes less than an hour. I try to fire 4 times a year using about 1 1/2 cords of sawmill scrap wood for each firing. Wood preparation is a big job requiring helpers. Plentiful seasoned and dry wood is a must. Wood firing is an amazing community building effort and quite different from much studio pottery work time alone in a studio. To help with that aspect I have incorporated a pizza oven into the kiln design. When the firing is done, we make and eat pizzas! Hard work but very rewarding.

Before the firing

After the firing

​​The trolley just after pulling it out. Note the twist bottle leaning with the brown topped jar; these two fused together during the firing. The jar was on the trolley near the center post with drip, the twist bottle was on the bag wall and they got too close, fusing up. To extricate them without losing other pots I had to reach in through a 6" gap, using my iPhone to "see" what was going on. I then removed smaller pots through the gap and made room to move larger pots off of the top kiln shelf so I could lift up the fused pair onto the shelf where they now sit. Fortunately, the only pot lost was the twist bottle which gave up a chunk when pulled from the jar. ​A small price for an important lesson with car kilns: leave lots of clearance!

​David presents a 6 weeks online workshop at TeachinArt (porcelain tips for wheel pottery).
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He shows potters how to push the limits of porcelain and demonstrates the easy way to get the best out of wheel throwing. 

Interesting books about wood firing.

• The art of firing by Nils Lou
• Wood-fired stoneware and porcelain  by Jack Troy
• The kiln book by Frederick L. Olsen (here you find diagrams and instruction on how to build different anagama kilns)

David in the TeachinArt studio during the recording of his online workshop

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