Nick,
Like a wood fire kiln, soda or "salt" fire kilns are heavily atmospheric. Salt (or cleaner burning soda) minerals are added to the firing which is, as I understand, otherwise essentially a reduction firing. These kilns are similar to wood fire kilns because the soda fluxes at high temperatures and creates a natural glaze that covers everything in the kiln as wood ash does in a wood kiln. The natural glaze in soda firings tends to be less viscous than an average wood firing, but both can vary quite a bit depending on the kiln, or fuel used.
While wood firing anagama kilns are actually derivatives of ancient Korea, Salt fire/soda fire kilns were developed in ancient germanic nations. Both create very interesting natural surface textures that are dependent upon the position in the kiln a given piece is fired.
I am an expert of electric firings and automatic kiln programing, I studied under a professional sculptor for years who specialized in this area and since those days I've expounded apon that knowledge. Firing in a soda or wood kiln is more of a treat for me.
-Sol Zimmerdahl
