My black surfaces are achieved fairly simply. I take the pieces red hot from the kiln and bury them in dry sawdust leaving them to cool. The white clay draws in the burnt carbon sawdust, to give a jet black finish. Alternatively, I sagger fire. This method is fairly simple. After the initial biscuit firing, the piece is placed in a clay sagger which is packed with sawdust and placed in the kiln, until the sawdust begins to smoke (just before the sawdust ignites). The pieces are then allowed to cool down.