It Takes a Village – Wood Kiln Firing
On Tuesday, May 23, the ceramics Alternative Firing class, along with students in the year-long wheel throwing pottery classes, spent the day firing Gould’s cross-draft, wood-burning kiln. Wood Kiln Firing is an intense process and can be a community event. Here’s how it went down.
In preparation for the firing, the students spent the term making many different pottery forms that would be put into the kiln. There were a variety of mugs, bowls, pitchers, covered jars, and teapots. A week before the firing, our class hauled a cord of firewood split by my father and Gould alumnus, Dan Grover ’63. All of the wood was used to fuel the kiln during the 17-hour firing. The wood not only fuels the kiln but also provides a glaze coating on the surface of the pottery.
How Wood Kiln Firing Works
As the wood burns, the ash is transported through the kiln on the tips of a ten-footlong flame. As the flame moves through the pottery, like water flowing through rocks in a stream, the ash is deposited on the leading edges of the pottery. As the ash builds up on the surfaces, and as the temperature exceeds 2250 degrees Fahrenheit, the ash begins to melt and form a unique glaze.
The Big Day
On a rainy Monday evening the day before the firing, my husband Joshua, students from the Alternative Firing class, and I met to load the pottery into the kiln. Each piece was carefully positioned on the kiln shelves for maximum surface effect results. Every piece had to be propped up on small pea-sized balls of “wadding,” a refractory clay like material that would prevent the melted wood ash from fusing the ware to the kiln shelf during the firing.
Feeding the Fire
The firing began at 7:00 am Tuesday morning and continued until nearly midnight. Throughout the day, the students and I took shifts to continually stoke wood into the kiln. Early in the firing, two small sticks of wood measuring approximately 2” x 2” x 24” were put into the kiln’s firebox every three minutes. Joshua and Sean Xie ’17 arrived at noon to help get the kiln up to 1500 degrees Fahrenheit. Stoking increased to two sticks every two to three minutes.
Throughout the afternoon Matt Chiasson ’17, Noah Grammas ’18, Elise Leary-Forrey ’18, Madsie Fisher ’18, Eva McMillan ’18, Pablo Borunda ’18, Emily Halporn ’17, Julia Harding ’19, and Molly Lento ’18 took shifts firing the kiln. By dusk, the kiln was up to 2200 degrees Fahrenheit, and even my studio intern Sasha Lennon stopped by to help stoke along with a number of students who passed through to check out the firing. By that point, wood needed to be added nearly every minute. A call and response formed as students on the front of the kiln watched the pyrometer that monitored the kiln’s internal temperature. When the temperature started to peak and then decline, indicating the need for more fuel, they called out “stoke.” Students on the rear of the kiln would respond “stoke,” and then add more wood to the firebox. They continued for hours calling out “stoke” or “stir and a stoke,” when the coals in the firebox needed to be agitated.
Pass the Salt
Around 9 pm the first “salt burrito” was added to the kiln. A “salt burrito” is a pound of table salt poured onto a piece of newspaper that is then rolled up like a burrito. This package is then stuffed into the firebox. Immediately upon entry, the paper combusts and the salt volatilizes and becomes a vapor in the kiln. The vapor, like the wood ash, flows through the kiln and deposits on the surface of the pottery. The sodium vapor fluxes and becomes a glaze on the pottery. This burrito process was repeated six times over the next two hours. The kiln reached its final temperature of over 2300 degrees Fahrenheit, or “Cone 10” in ceramic terms, around 11:30 pm. At that point, senior Sean Xie, added the final piece of wood and the kiln was closed up and left to cool down naturally over the course of the next day.
On Thursday morning during their class, the Alternative Firing students met to unload the wood kiln and inspect the results. Everyone was pleased at the unique and unpredictable surfaces created in the atmosphere of the wood kiln.
The process can be repeated many times, but the results are always unique to each firing. The results can be affected by the placement of pottery in the kiln, length of firing, wood used, type of clay used, level of reduction atmosphere inside the kiln, rate of temperature increase and decrease, and even the weather. Wood kiln firing is a rite of passage and a yearly event at Gould, but the end results are as distinctly unique as the students themselves.