Drying and Firing
Once the shaping of the vessel is complete, it must air dry undisturbed on a shelf for two to four days to dry. If it is not completely dry when it is fired, moisture in the clay will cause steam in the kiln and crack the pot.
When thoroughly air-dried, the pot is ready for bisque firing. In this step, the vessel is quite fragile. Although it can be handled for placement in the kiln, it will crumble if hit and dissolve if moistened. During bisque firing, the pot is fired in the kiln to 1845ºF, which hardens it sufficiently to go through the glazing process. At this stage the vessel is still porous enough to absorb the moisture in the glaze, which allows the glaze to adhere to the vessel.
Because of its strong, durable structure when fired, stoneware makes an excellent clay for useful vessels. Mid-range stoneware clay fires to maturity between 2200ºF and 2283ºF (cones 5-7). High-fire stoneware clays fire in the 2300ºF to 2400ºF range (cone 8-11).
Glazing and Finish Firing
After the vase cools from bisque firing, it is taken from the kiln and hand-dipped in a glaze. Special effects might also be added, such as air brushing or hand painting. The color of the glaze at this point is not the color of the finished pot.
Once glazed, we fire the stoneware to temperatures over 2,000ºF. Then the glaze ingredients fuse together in the firing to form a glass-like coating. The vessel is then very durable and can be put to daily use, including in the dishwasher. At The Potter’s House, we fire our pottery in one of our two types of kilns—electric or gas-fired.