Bisque - The blank white ceramic pieces that you see in the front of our shop, ready for your creative endeavors.
Bisque firing - The state at which all moisture is removed from the pottery through the firing process. After this process is complete, the piece is ready for painting.
Ceramic paint - color pigments combined with glass frit and other raw materials.
Crawling: A bare spot (from the shrinking of a glaze) on a finished piece where oil or grease prevents the glaze from adhering to pottery.
Crazing: Crazing is a network of fine hairline cracks that appear on the glaze surface. If the glaze, during the cooling process, shrinks more than the clay body you get crazing. There are two types of crazing, immediate and delayed. If you get delayed crazing, weeks or months later, it is probably caused by moisture getting into the ware.
Glaze - the clear coating that we apply to your piece after it is dry. Glaze seals the piece from moisture and makes all the colors glossy and bright.
Kiln - A furnace or oven for burning, baking, or drying, especially one for firing pottery. To glaze- fire to Cone 06, which is approximately 1830 degrees. It takes the kiln about 7 to 8 hours to get up to temperature and about twice that to cool down.
Pinholes & Craters - Pinholes and craters are two of the most common glaze surface defects. After firing, you may see small "pin sized" holes on the surface of the ware (pinholes) or you may see larger "crater like" impressions like the surface of the moon (craters).
While there are many things that can cause pinholes and craters, the causes are related to gases coming from either the clay body or the glazes that have not smoothed over after firing.
The clay body, and even the glaze, contains clays and other minerals mined from the earth. These contain some organic matter (i.e. plants, etc.), carbon and more. These materials form gases during the firing process and can result in pinholes and craters.
Shivering - When you fire bisque in the glaze firing, the bisque will basically expand during the firing and contract during the cooling phase. Shivering is typically defined as occurring when the bisque and glaze shrink at different rates. If the bisque shrinks more than the glaze, the glaze has nowhere to go but "shiver" off or "flake" off the bisque.