The Process, Continued - Pitfalls
the manufacturers specs, the pot will not be fully vitrified and will be weak and more apt to break. Worse than that, if the clay if fired to a much higher temperature than the manufacturer intends, it can become brittle, or even worse, melt down in the kiln, fusing itself to the kiln shelves and to the other pieces in the kiln.
For a pot to retain its intended shape, it must dry evenly. If the piece dries unevenly it will warp. So, potters usually cover the piece loosely with plastic to allow some air to get in and dry it evenly. Lots of things can make it dry unevenly. For example, if it is exposed to sunlight for a long time on only one side, or if it is only partially covered by the plastic, or if air currents hit different parts of the pot unevenly, it can warp. If it is bumped while still wet, it can be deformed. If the potter throws the piece unevenly (that is, if the walls aren't of a uniform thickness), then the pot can warp as it dries.
A thousand things can go wrong in the glazing process. The glaze can come out the wrong color or “look”. If the glaze is applied too thickly, it can run off the pot during firing (sometimes destroying other pieces that get dripped on, or ruining the kiln shelves) or can crack and crystallize. If applied too thinly, it can look washed out, or not give a glaze effect at all. If it's applied too thickly or unevenly, the glaze can “crawl”—i.e., recede from certain spots on the pot. If the glaze is applied unevenly, the piece will end up looking streaky. Some glazes give off fumes