|Monthly Tech-Tip |
Failure is often not something specific. The greater the wall thickness variation across a piece the more difficult it is to dry and fire it evenly. The stronger the rim the better it will withstand the stresses of drying and firing. The finer particled and more porcelaneous the body the more difficult it will be. After throwing, the longer a piece is left drying with the rim up the greater the moisture content difference will be between it and the base. During early stages of firing, the better the air flow and slower the heat-up through water-smoking, the better. The earlier a bowl can be trimmed the better the success. The less a soft or leather hard bowl is handled such that it goes out-of-shape, the better. The slower and more even the drying the better the success. The slower and more even the heating a piece is subjected to the better the success. The more that heat can reach all sides of the piece the more evenly it will heat up during firing. The less the point of contact between the base of the bowl and the kiln shelf, the less the shelf will heat-sink it and increase temperature gradients within it.