Soda firing is an atmospheric firing process that utilizes sodium to help surface the pots during the firing.
Similar to wood firing, bisqued pots are loaded into the kiln without any pre-applied glaze. When the soda 'bombs' are tossed into the kiln near top temperature, the soda instantly vaporizes and is carried by the flame throughout the chamber. The soda acts as a glaze and reacts chemically with the forms to create surface on the pots.
Robin's thesis work at Utah State University was an exploration of how cooling rates affect both texture and colour development in soda kilns.