Throwing Pottery

Prior to throwing a piece, the clay must be wedged to make it’s texture even throughout the piece. The clay is attached to the wheel head, centered and then thrown into it’s shape. This bowl was thrown using a wood bat. The bat allows me to remove the bowl from the wheel without touching it.

After the pot has been throw, the piece must be allowed to dry to a leather hard state. Leather hard means that the piece is hard enough to handle without marking the surface, but soft enough to carve. Once the pot becomes leather hard, the bottom of the pot can be trimmed. The leather hard drying time takes about 8 to 12 hours.

To trim a foot on a pot, it is placed back on the wheel, centered, and attached. Then trimming tools are used to trim a foot. The function of the foot is it allow a glazed pot to be fired in a kiln without sticking to the kiln shelf. This is true because the foot ring is never glazed. The foot also allows the bowl to slide across a table’s surface with the least amount of friction.

After trimming, the piece must be allow to dry completely. I refer to the pot as being bone dry. Once the pot is bone dry, the piece will be sanded and then placed in the kiln for a bisque fire. The clay I use is Earthenware clay. This is a low fire clay. The kiln must reach a temperature of cone .04 (1,940 degrees F). Once the clay piece reaches this vitrification temperature it turns to stone.

The bisque firing of pottery takes many hours and uses a significant amount of energy. My average kiln firing time is 6 hours. Image running your kitchen oven for 6 hours on high. My kiln (oven) must be run from ambient temperature to 1,940 degrees. After the kiln reached 1,940 degrees, it turns off and is allowed to cool down to below 100 degrees. It takes around 18 hours to cool.

Rule number 1: Never bisque fire a kiln unless it is full. The cost of running your kiln must be spread across as many pots as possible.

Once the piece has been bisque fired, the surfaces are porous. To make the piece functional, it must be glazed. Glaze is made mostly of Silica, Alumina and Flux. But basically it is a liquid substance that turns to a glass like surface when applied to a bisque pot and fired. Glazes can be brushed on, poured on, or the pot can be dipped into the glaze.

This bowl has a red glaze in the center and dark green glaze on the outside. Note: the colors changes during the firing.

After a pot is glazed and allowed to dry completely, it can be placed into the kiln for a glaze fire. I use low fire glazes. Low fire glazes fire at code .06 (1,818 degrees F). Once the kiln temperature reaches code .06, the kiln turns off and is allowed to cool for 18 hours or until the inside temperature is 100 degrees F.

Here is the finished bowl. From start to finish, it takes about two weeks. Rule number 2: Never glaze fire a kiln unless it is full.