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 or not the theory is true we know this method of creating pottery eventually developed into firing with wood in a pit. This ancient technique is still practiced in many parts of the world today.
Sawdust firing is a modern take, though its typically done in a barrel, or an old burnt out kiln. At first glance it appears to be completely random 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 a variety effects within a single piece.
Loading the kiln is quite simple.
First, sawdust is layered in the bottom of the barrel before the pottery is set in. Next, more sawdust is added around the pots until they’re 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 smoulder. As the sawdust and wood shavings slowly burn down the smoke and fumes sear into the clay surface. This can take anywhere from twelve hours to three days.
With a little trial and error it’s possible to achieve many effects. The potter wants to think about a specific 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 slurries are applied to a bone dry pot, then burnished until smooth. For a matte finish the clay is left rough, and/or painted with stains.
Various items may be attached to each piece including foil, banana skins (for the potassium), wire wool and strands of copper, to name a few. In addition, oxides and salt may be added to the sawdust when loading the kiln to give some subtle colour to the pots.
When a sawdust kiln has finished 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.