Sawdust firing: It is an easy way to fire clay, the pieces are smoked with sawdust.
Using bricks, build up a shaped cube with a removable lid. A clay pot or a metal bucket can also be used, the hole at the top serves for the circulation of smoke, which rises above the clay. Fill it with the pieces which have to be fired and add sawdust. Each piece must be surrounded by sawdust and they must not touch each other. The number of pieces depends on the size of the container. Put a few sheets of newspaper and bits of wood at the top and set light to them, so the sawdust starts burning at the top and the fire moves downwards. Cover it with the lid and leave it firing until the sawdust is consumed, this may take up to 24 hours. Allow it to cool slowly; the clay has been converted into smoked bisque.
Click to see a very good video Sawdust Fired Ceramics