Soda Firing
Process
Soda firing is a process in which soda ash, otherwise known as sodium carbonate (Na2CO3) is introduced into the kiln at or near the peak temperature of the firing. Sodium Bicarbonate, otherwise known as baking soda, can be used as an alternative. Ways of introducing this into the kiln include spraying soda ash dissolved in water, dumping a solid mixture of soda ash and whiting into the fire box (Gail Nichols method), or putting it on wood to be added to the kiln. When the soda ash is introduced, due to the intense heat, vaporizes and is carried throughout the kiln with the path of the flame. As it moves along, it begins to glaze the wares inside the kiln chamber as it is attracted to the silica within the clays, slips, and glazes. The soda ash also interacts with the alumina and metal oxides within the wares; these in conjunction with the silica, atmosphere of the kiln and amount of soda ash built up can create a variety of colors, textures, and surfaces.
In 2015, during my first semester of undergraduate studies at the University of Wisconsin-River Falls, I had my first experience in the salt / soda kiln. My friends invited me to participate in their salt firing in this kiln; I remember staying up late, past dark loading the kiln and how joyous that time was. I didn’t partake too much in the actual firing but was so excited about the results. Soon after, due to heavy use on the University communal cross draft kiln, as a class we brought down the kiln and began rebuilding it. During my third semester at UWRF we laid the final bricks to the chimney of the new salt / soda kiln. This is where my dialogue with soda firing began; I had my first soda firings in this kiln only knowing to follow the lead of what my friends did while salt firing. My first firings were rough, but the results kept me coming back for more every time. The slips that I used yielding exciting colors and captured the movement of the flame. During my third and fourth year at UWRF I really began to delve deeper into trying to understand soda firing and how atmosphere, materials, and soda ash all affect each other. Through generous funding from URSCA (Undergraduate Research, Scholarly, and Creative Activity) at UWRF, I was able to research the relationship between these three things and form a deeper understanding of the effect that they have on each other. In Spring of 2019 I graduated from UWRF and took a short hiatus from soda firing to pursue wood firing as a cheaper alternative. In Winter of 2019, I began soda firing again at Northern Clay Center in the small down draft kiln. Everything about this kiln was different, but I was able to adapt and deepen my understanding of firing soda kilns. In April of 2020 I was awarded the 2020 Jerome Ceramic Artist Project Grant through Northern Clay Center and the Jerome Foundation. Through this grant, I proposed to continue my research of the interaction between ceramic material, soda ash, and kiln atmosphere during the down-firing stages of the firings that I do. I hope to learn more about the process of down-firing and understand it through quantitative data.
On this page I share my process, research, recipes and go into great detail on my 2020 Jerome Ceramic Artist Project Grant research. My aim with sharing this information is to dissert my findings and create a greater understanding for soda fire research pertaining to down-firing. Of course, I have to acknowledge the great book, Soda, Clay, and Fire by Gail Nichols. If you do not have this book already, it is a wonderful resource for learning about soda firing. Her research has informed mine and created a base for my understanding of soda firing. With this, I have found my own avenues of research and development. By sharing my research, I hope to do the same for others; create a resource to learn from and a place to inform the beginning of others’ research. Please reach out if you have questions, want to chat about soda firing hypotheticals or are interested in my research.
