Geoglazing in Traditional Japanese Wood Fired Kilns
Mentor 1
Randy Johnston
Location
Fireside Lounge
Start Date
24-4-2015 9:20 AM
Description
An experiment was conducted to explore firing techniques that use renewable resources like wood and creating glazes from locally sourced materials. Glazes were developed using rhyolite from New Mexico, feldspar from North Carolina, iron bearing granite from Minnesota, along with other materials like deer bone, and wood ash left over from past kiln firings. The stones and bone were ground into a fine powder then mixed together starting at 100% of one material and adding another in 5% increments until it is a 50-50 mix. Test tiles were dipped at each addition. Some glazes were designed to show where a mixture turns into a slip (a rougher surface but still adheres to the surface) and when it changes into a glaze. After the tiles were fired an evaluation was done to determine which mixture yields the best result. The test tiles were fired in a traditional Japanese wood- fired kiln called an Anagama kiln. This kiln can hold many pieces but takes three days to load, five days to fire, seven days to cool and one day to unload and clean. The kiln must be stoked around the clock while it is being fired so it is extremely labor intensive. Because vast amounts of wood ash are being introduced to the air in the kiln during the firing, the ash settles on the ceramic pieces adding design and color.Another set of tiles with the same glazes was fired in a salt kiln. This kiln was quite small in comparison and was fired with gas. Near the end of the firing salt was introduced to the atmosphere creating some decoration. These will be used to compare energy used (gas, wood, manpower), firing time, amount of work fired, and the quality of the glazes created and evaluate the potential of increasing the use of kilns that use a renewable energy source like wood.In the future I would like to use these tiles as a teaching tool to demonstrate the potential for color variations and show the possibility of diversity in making glazes with only a few materials.
Geoglazing in Traditional Japanese Wood Fired Kilns
Fireside Lounge
An experiment was conducted to explore firing techniques that use renewable resources like wood and creating glazes from locally sourced materials. Glazes were developed using rhyolite from New Mexico, feldspar from North Carolina, iron bearing granite from Minnesota, along with other materials like deer bone, and wood ash left over from past kiln firings. The stones and bone were ground into a fine powder then mixed together starting at 100% of one material and adding another in 5% increments until it is a 50-50 mix. Test tiles were dipped at each addition. Some glazes were designed to show where a mixture turns into a slip (a rougher surface but still adheres to the surface) and when it changes into a glaze. After the tiles were fired an evaluation was done to determine which mixture yields the best result. The test tiles were fired in a traditional Japanese wood- fired kiln called an Anagama kiln. This kiln can hold many pieces but takes three days to load, five days to fire, seven days to cool and one day to unload and clean. The kiln must be stoked around the clock while it is being fired so it is extremely labor intensive. Because vast amounts of wood ash are being introduced to the air in the kiln during the firing, the ash settles on the ceramic pieces adding design and color.Another set of tiles with the same glazes was fired in a salt kiln. This kiln was quite small in comparison and was fired with gas. Near the end of the firing salt was introduced to the atmosphere creating some decoration. These will be used to compare energy used (gas, wood, manpower), firing time, amount of work fired, and the quality of the glazes created and evaluate the potential of increasing the use of kilns that use a renewable energy source like wood.In the future I would like to use these tiles as a teaching tool to demonstrate the potential for color variations and show the possibility of diversity in making glazes with only a few materials.
