The pot may be further decorated with incised lines or punctuation's made with a fingernail or stick. In addition to decoration, roughening the surface may also have made an otherwise slick pot easier to handle. After the pot had completely dried it was fired in a bonfire of wood and or brush. This firing method, with the fuel in close proximity to the pottery, resulted in a pot with a variety of colors depending on the amount of iron oxides in the clay and how they reacted with the fire. This was fortunate because higher temperatures may cause the calcium carbonate in the bone temper to decompose into calcium oxide.
Calcium oxide absorbs moisture from the air and expands in size creating paIls or cracks.
Preliminary burning of the bone may reduce this effect in that the expansion occurs before tempering material is added to the clay to make the pot. Quick firing and the gases given off by the burning fuel may also slow the decomposition of the calcium carbonate. In any case, spalls are not generally found on Leon Plain sherds. In some cases, this porosity can be advantageous in that drinking water is kept cool due to the evaporation of the moisture on the exterior surface of the pot. There is no evidence that such post-fire sealing was ever used by prehistoric potters in Central Texas.