FAIRBANKS — Art students huddled around a 2,400-degree grease fire behind the university experimental farm in 13-degree weather on Thursday. A big tank of vegetable oil fed the flames inside a fire box and heated their pottery within one of Fairbanks’ newest artistic achievements — a vegetable oil-fired kiln.
A University of Alaska Fairbanks ceramics class designed and built the kiln during the summer at “kiln city,” an outdoor clearing between the reindeer pens and the university ski trails. Kiln City also contains four wood-fired kilns.
Few universities have vegetable oil kilns because they are a relatively new concept and take up lots of space. Most use indoor electric kilns.
The kiln, which was paid for with a $6,000 grant from the university sustainability committee, will lessen the carbon footprint of ceramics and offer a new aesthetic to artists. The experimental design also tests how the technology fares in cold weather.
“So many potters consider themselves environmentalists. But then you go through so much wood firing your pots,” said Heidi Morel, a art graduate student who led the charge on the project. “It also adds a little bit of spontaneity to the process of firing.”
They filled the 3-square-foot kiln with about 100 stacked clay pots, vases and bottles on Thursday, the second time they have fired it so far.
Made of brown brick, the kiln looks like a big chimney or a pizza oven. They modeled it after a Fastfire kiln, which has a pottery chamber directly above the fire box, but the design had to be adapted to the Fairbanks climate.
“One big thing is, when it gets cold the fuel gets really thick,” Morel said.
A 55-gallon drum of oil was contained in a larger drum housing three block heaters and mounted by the top of the kiln. When a valve is opened, oil flows through thick piping onto metal plates inside the fire box. From there, it drips onto a fire first stoked by wood, which generates enough heat to burn the oil efficiently.
“We start off with a camp fire and get it going to 700 degrees. Then we pull out the wood grates and put the drip in,” Morel said.
Potters have used combustible products like diesel or waste oil to supplement the heat of wood-fire kilns, said Jim Brashear, a UAF art professor who taught the kiln-building class, but “a greener idea in this energy crisis is vegetable oil,” he said.
To jump from the 700-degree wood fire to 2,400 degrees, the kiln uses 30 to 40 gallons of vegetable oil donated by local restaurants, schools and businesses.
A kiln needs to be hot enough to turn the glaze on the pot into glass. This process is facilitated by adding a flux, a compound like lead, salt or soda, which lowers the glaze’s melting temperature. The UAF class sprayed a mix of soda ash, baking soda and water into the chamber once it was hot.
“When you spray the soda in, it volatilizes and combines with the glaze to make an interesting sheen on the pot,” Morel said.
But if there is salt in the recycled vegetable oil, it adds extra flux, Brashear said.
“The bottom is usually filled with spices,” said Morel, holding a five-gallon jug of vegetable oil she picked up from Pike’s Waterfront Lodge. “People clean their fryers differently.”
These factors add an element of spontaneity to using the kiln, she said.
“In an electric kiln, it becomes predictable if you’ve used the same clay bodies and glazes for awhile.”
This is the first time Sara Grocett, a junior in the class, has heard of a vegetable oil kiln.
“I think it’s wonderful the system gave us a grant to build it,” she said.
As exciting as the new kiln is, the best part is opening the door once all the work is done.
“We wait two days to let it cool,” Morel said. “It’s like Christmas Day.”
Contact staff writer Molly Rettig at 459-7590.