My old updraft stoneware kiln I've had since I was eighteen. Converted to a soda ash kiln years ago. I got this while apprenticing with Brent Bennet Designs in Costa Mesa back in high school. Moved many times and rebuilt a few times, it now is retired and waiting another rebuilt life.
Here is my current soda ash kiln. Built with a trolley door which provides easy loading and unloading. Fired with propane gas, it has two burners which provide over 900,00 BTU's, firing to cone 10 (2345F) in under 10hrs.
My soda ash process and materials:
Studio entrance, circa 6/2016
Spraying soda solution into the ports of my small updraft kiln.
Checking draw rings to inspect soda firing.
My interest in vapor or atmospheric firings started as a junior in college at the University of Washington. Salt firing was my first introduction to the process. I now use various combinations of soda ash/ sodium bicarbonate to achieve my vapor fired effects.
I love the way slips, glazes and clay interact with the vapor as it travels with the flame through the kiln. Unpredictable and always surprising, each kiln opening of a completed firing is an event that is looked forward to. The pieces are kissed by the vapor as it finds it way through the ware and out the flue of the furnace.
When the kiln reaches a temperature where the glazes and clay bodies flux or melt, (in this case around cone 8, approx 2280F) the solution of soda ash is sprayed with a commercial grade sprayer and another compound of soda ash, sodium bicarbonate, whiting (calcium carbonate) is deposited into ports above the burners. I fire all these pieces to cone 10.
Most of my work is thrown and altered in some fashion. I come from a background of production pottery and have incorporated these techniques into my work, which has most always been vessel oriented.