Explaining Black on Black vs Black on Graphite
Black on Black
Black on black pots start with shaping any natural color clay to the desired shape. After drying, sanding and rubbing smooth with a polished stone or bone (Juan likes to use a piece of antler), the piece is painted using a clay slip (very liquid clay) and fired using an oxygen reduction process. This technique results in a matte black design over a shiny deep black surface.
Oxygen Reduction Firing
When setting up the firing area (usually in the back yard of their homes), the space is cleared, and a small amount of fuel is placed within the area, the piece to be fired is placed above the fuel using a stand, wire grid or even rocks, then covered by the bucket. Care is taken so that the bucket (or other cover) is flush to the ground, and the edges sealed with dirt or ashes so that oxygen does not circulate within the firing space where the pot is. The bucket is piled with fuel (either cow chips or cottonwood bark) and set ablaze. The heat from the fire sets alight the fuel under the bucket, burning up the oxygen and causing a chemical reaction that turns the clay black.
Black on Graphite
Several years ago, Suzie Lopez signed the bottom of a pot with a pencil before firing it. The pencil marking not only survived the fire, but took on a permanent silvery finish. TSuzie and her friends liked the finish and were soon buying pencils, grinding the graphite to a powder and making a liquid solution to coat their pots. Later, traders introduced the potters to copier toner to supply the graphite powder for the solution. After drying, the graphite surface was painted with a design using a clay slip (very liquid clay), then firing the pot using the reduction method. This technique results in a matte black design on a shiny silver metallic finish.