Modern scholars have theorized that the first clay vessels were created when baskets, waterproofed with a lining of wet clay, were accidentally burned in a fire. The clay was heated to a high temperature, and pots were formed. Whether the theory is true or not, we know that this form of creating pottery eventually developed into the practice of firing with wood in a pit. In many parts of the world pit firing still goes on. Sawdust firing is a similar process. Its typically done in a barrel or an old burnt out kiln.
At first glance it appears to be a completely random technique yielding unpredictable and uncontrollable results. But in fact, the shape of the form, the texture of the clay surface, and the application of glazes can all help to create various effects within a single piece.
Loading the kiln is quite simple.
Sawdust is layered in the bottom of the barrel before the pottery is set in. More sawdust is added around the pots until completely covered. More pots are stacked on top and more sawdust is added until the barrel is full.
A fire is lit on the top and when everything is burning well the kiln is covered and left to burn out. This can take anywhere from twelve hours to three days. As the sawdust and wood shavings smoulder the smoke and fumes burn permanently into the clay surface.
With a little trial and error it is possible to achieve many effects. The potter wants to think about the desired look while making the piece and create the kind of surface to match the desired effect. Various shapes and textures will respond differently to the smoking process. For a smooth finish a number of thin layers of clay particles are applied to a bone dry pot and then burnished to a smooth surface. For a matte finish the clay is left rough, and/or painted with stains.
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Various items may be attached to each piece including foil, banana skins (for the potasium), wire wool and copper, to name but a few. In addition, oxides and salt may be added to the sawdust when loading the kiln to add subtle colour to the pots. The weather will also contribute to the effects. When a sawdust kiln has finsihed burning and the pots are cool they are washed to remove ash, and set aside to dry. At this point waxes and polishes may be used, but often the results stand on their own.