Bone dry

Bone dry is the last stage before the kiln, and it earns its name honestly, a piece at this point feels light, cool colored rather than damp gray, and sounds distinctly higher pitched when tapped compared to a leather hard pot's dull thud. All of the water that was physically mixed into the clay has evaporated, leaving only the water locked into the clay's molecular structure, which will only leave during the bisque firing itself.

This stage is also the most fragile point in a pot's entire life. With no moisture left to give the clay any flexibility, bone dry ware chips, cracks, and shatters far more easily than either wet or leather hard clay, and thin areas like rims and handles are especially vulnerable to a careless bump. Uneven drying is the other major risk here, if handles, rims, or thin walls dry faster than thick bases, the resulting stress can produce cracks before the piece ever reaches the kiln.

The practical fix for both problems is slow, even drying, achieved by loosely covering pieces with plastic for the first days so thin and thick sections dry at closer to the same rate, then uncovering fully once the piece is uniformly leather hard. Cold studios in winter slow drying further and can tempt potters to rush pieces near a heater, which usually backfires with cracked rims. Handle bone dry greenware as little as possible, supporting it from underneath rather than by a rim or handle, right up until it goes safely into the kiln for bisque firing.