Soda Firing

Soda Firing Statement


What is soda firing?  What are its essential qualities?  How is it like and different from salt firing?  Why do I soda fire? 


 dynamic varied surface possibilites with soda firing.


Soda firing is an interactive type of firing that introduces sodium vapor into the kiln’s atmosphere, which then forms a bond with the clay it comes in contact with under heat and pressure inside the kiln.  The sodium becomes a glaze when combined chemically with the clay elements, the very same type glaze that is produced in more traditional salt firing. 


Salt firing was developed in the 17th century in what is today Germany and was used to glaze large kiln loads of white stoneware bottles and wares for the wine production in the Rhine valley.  One of the few historical glazing techniques developed in the western world, this strong durable ware was a simple way to glaze many pieces quickly and efficiently.  The bottles made of a white high fire clay fired out white to gray in color and often used cobalt markings and brush work.  Salt firing was also utilized in colonial America and in many potteries in the U.S. throughout the 18th, 19th and early 20th centuries.  Crocks, jugs, and utilitarian wares of all sorts were fired in this way with the characteristic orange peel surface of an almost clear glaze that enhanced natural clay colors and surface fingerprints and marks.  Industry glazed sewer pipe in this way in many areas of the United States.  Simply add salt to a fire over 2000 degrees and a vapor is formed that attacks and glazes everything with silica in it that it comes in contact with.  The brick insides of kilns were glazed, the shelves and kiln furniture,  so much so that wares were stacked with wadding,  small bits of refractory clays that would easily separate after cooling, leaving decorative markings and traces of where they had been. 



In the 1970’s with increased ecological concern, soda firing was developed as a way to keep the beauty of much loved salt fired ware without producing the cloud of sodium vapor gas and toxic chlorine gas that was a by product.  Soda ash, sodium bicarbonate, and other sodium products were experimented with and varying results produced.  Salt turns into a vapor very easily when introduced to a hot fire but some of these other products just sank to the firebox floor.  Ways were learned to turn these product to vapor and to help the vapor move through the kiln and glaze wares.  Sawdust,  and other combustibles were added or soda was mixed with water into a solution then added.  Hydrogen reduction takes place when water is introduced to the kiln, and as the glaze moved through in different ways differing results were achieved.  Results “just like” salt firing were not always produced but a whole new vocabulary of surface and possibility was.  Artist have seen and developed these possibilities in ways that communicate feelings and thoughts through color, metaphor and process.


 spraying a soda and water solution into the kiln


Some of the essential qualities of soda firing include its clear sodium glaze, the orange peel surface, but usually in a more varied way than salt firing.  One side of piece may be mottled with a heavily glazed area and the other side “flashed” with a dry or brilliant orange flame pattern. 


Soda fired juice cups of porcelain clay with slips applied... flashing marks and orange peel surface.


Soda firing accentuates and makes use of the natural clay body.  Clay exists in numerous colors from white to brown and grey and all sorts of shades in between.  Soda glaze is a clear and transparent sealing of the surface of the clay body and can thus bring out these different colors and also show finger marks, accentuate throwing and cutting marks and stretching thus it “tells” something of what the clay is made of and also how the clay was formed by the artist.   Sodium is a part of many glazes,  (coming from sodium feldspars and other glaze components).  In small amounts sodium helps produce brilliant colors and bright and glossy surfaces.  In larger amounts it can bleach out colors and wash out clays.  The soda affects slips and glazes that have been applied to wares changing their color, surface and appearance.  As it connects with those wares depending on how they are stacked in the kiln it produces natural highlights and variations in ordinary and extraordinary ways. 


espresso cup and saucer

heavy soda on outside of cup produces textured and mottled surface orange flashing on underside of saucer where less soda atached to clay body.


I love soda firing because of the variety of surface, color and metaphorical possibilities it offers.  Creating color under the intense heat and in the midst of the transformational process of firing speaks to the ineffable mystery of how our own characters are shaped and formed.  The building up of layers of surface, … starting with the material itself, adding to it the way in which the piece is formed, continuing with adding slips, patterns and symbols and color with applied glaze, then bringing it all to maturity through careful, experienced and hopeful stacking and firing of the kilns makes work with a depth of meaning I value.  I find the richness carried in the creation and story of a simple pot to be a pointer to the richness and complexity found in people, relationships, stories and histories in the world.  










Two sides of a soda fired bowl made of groggy stoneware.  left side received more soda and is thus lighter in color, ......somewhat "washed out"


I also enjoy sweating with the fire, gauging and reading its nature and qualities.  I utilize this great natural force for the transformation of material into useful and beautiful objects that tell a story about themselves and about the intentions that created them.  I appreciate how careful observation and attention to detail can produce insight, which then can be used to express mastery, competence and understanding, also contained in work.  Soda firing enables me to encode important information into pottery that I communicate how I feel about quality, mystery, and transformation through experience.



 Teapot soda fired on its side.