Kat Morrell Ceramics
Pit Firing Process
Pots are covered with Terra Sigalata, then bisqued to cone 08.
Pots are nestled in sawdust. Areas buried will be solid black. Charcoal brickettes placed around edges to promote even heat.
Minerals (rock salt, copper carbonate and copper sulfate) are sprinkled around the pots but not touching them. Lately, I have been making sure the minerals are deep in the sawdust so they volatilize later in the burning - when the pots are hot enough to accept the fumes. 
Pots are covered with kindling and wood, then torched. Doing a little dance to the fire Gods seems to help the process. 
I keep adding wood (carefully) for around 1 hour, being careful to have an even cover of wood to cover the pots. The pots are left to cool overnight. The colors emerge as the pots cool and the minerals are trapped inside the clay matrix. 
The pots are dusted off and vacuumed inside. I don't wash the pots in water because they can absorb water and the salt will leach out. The final step is to heat the pots in the oven to 180 degrees, then apply a thin layer of Butcher Wax and buff to a soft sheen. 