Atmospheric Firing
above right to left: wood fired dome jar, and 2 soda fired jars. details on left.
Atmosphere, in regards to firing ceramics, has to do with the type and quality of the air in the kiln during the firing process. The chemicals, compounds, and mixtures of elements present combine with the clays, slips, and glazes on the work to create colors, textures, and surface depth. Atmosphere affects the general surface of the work and informs its overall character.
Interior of red hot soda kiln ( 1850 degrees). Visible to the trained eye are bricks with lines where they meet in the very back. Then, one can see the outline ( triangle) of a dome lid jar. In front of the jar are four "cones" tilted to the left, and two cones tilted to the right. Pyrometric cones measure the the effect of heat over time on a ceramic material, .. temperature, as well as time are important factors in ceramic" heat work". In this photo the atmosphere in the kiln is clear enough to see through, because it is relatively oxidized. A "reduction" atmosphere is "thicker' and cloudier because it is full of, or rich with, carbon seeking oxygen. It finds and combines with oxygen in the clay and glaze.
There are numerous aspects to atmospheric firing. One has to do with the intimate, interactive engagement with fire, and how that relates to being involved with as much of the complete (creative) process as possible. Another has to do with the actual qualities sought after in the work. A third aspect important to me has to do with the work of creating meaning through metaphor in Art.
right: spraying a solution of soda ash and water into the 2200 degree kiln, which interacts with the clays, slips, and glazes in the kiln.
Every fire, every kiln has some type of atmosphere, in an electric kiln for example, one can have a clean, oxidized, air quality, repeatable, reliable, controllable and measurable. Electric kilns are important tools with a certain range of possibilities. In contrast, much of the 20th century studio pottery movement saw the development of reduction firing with different types of gas, oil, and wood as a fuel source. The long Asian traditions of Japan, China and Korea had been developed firing in this type atmosphere and glazes such as Celadons, Shinos, Tenmokus, Copper Reds, Chuns, and others with rich surfaces were possible only in a fire that contained a reduced amount of oxygen and was rich in carbon. The carbon combines with the glaze elements at certain vital points in the firing producing certain colors and surface qualities that many ceramicists in the 20th century pursued and developed in a variety of ways.
Left: testing the elements in an electric kiln to see if they are still good. Elements are wire coils that carry electricity through the kiln and release heat. Electric elements produce clean oxidized heat, reliably and repeatably.
Some "low fire" atmospheric processes include pit firing, smoke firing, and brush firing as well as "American" Raku . Many of these processes have been practiced around the world by traditional peoples and cultures, with ceramics marked and colored by the flame and firing process. They are still in use and development today and are still full of mystery and discovery.
“High temperature” atmospheric firing today generally refer to wood, soda, and salt firings, or combinations, that utilize both reduction and oxidation atmospheres but essentially create glaze in the kiln in a more interactive way. Different chemical elements are introduced to the kiln in process. The style and configuration of the kiln affects the possibilities of the surfaces. Various clay qualities are brought out and celebrated for their characteristics. New vocabularies of surface, color, texture have become possible for the artist to explore, develop and utilize.
East Creek Anagama wood firing. These giant wood burning kilns utilize wood for heat and also its ash, its mineral content, carbon all combine with the clay in the kiln creating a rich atmosphere which in turn glazes and colors the pieces in the kiln.