The first step in making bricks was to find a suitable supply of the main ingredient, clay. Slaves excavated the clay by digging an open clay pit. In Columbia, the clay pit that slaves likely used to make bricks was located on a square plot bounded on the north by Greene Street, the south by Devine Street, and the east by Williams Street. Slaves took the moist mineral clay and packed it into a mold usually made of wood and sometimes lined with copper. The size of these molds could vary based on the type of clay slaves were using. Bricks that were constructed of a stronger clay material would often shrink during the firing process, so slaves would cast the bricks in a mold slightly larger than the desired size of the brick in order to accommodate for this shrinkage. Slaves then left the resulting brick molds on the ground to air dry. After the brick molds were dry, slaves would remove the bricks from their mold and place them into a kiln or fire pit, which would often heat up to 2000 degrees. Since up to 20,000 bricks could be placed into the kiln at once, this process, known as firing, produced bricks of varying quality and composition. The result was that bricks nearest to the fire became very hard, sometimes brittle, while those that were furthest from the fire often maintained a soft core. After firing at this temperature for a few days, slaves would gradually decrease the temperature of the kiln by opening air holes, which allowed the bricks to cool.
Close-up of Brick Yard, 1847 map, SCDAH
1847 Map of Columbia. Note the Brick Yard at the west end of Devine St., SCDAH