leatherhard

Leatherhard is a term used in ceramics to describe a stage in drying clay. At this point the clay is stiff enough to hold its form but still contains moisture and is somewhat plastic. It has passed the fully plastic greenware stage, yet is not completely dry. The exact timing varies with clay body, thickness, and environmental conditions, but leatherhard pieces feel firm and can be handled without deforming, while still offering enough moisture for carving, incising, or joining.

Common uses at the leatherhard stage include trimming rims, refining surfaces, attaching handles, and adding surface decoration with slip or carving. Because the clay is still damp, surfaces can be worked with tools, and joints can be reinforced. However, leatherhard clay is more fragile than plastic greenware, so careful handling is important to avoid cracking or distortion as shrinkage continues.

Managing drying is important to prevent defects. Pieces are often partially wrapped or covered to slow moisture loss, then gradually exposed to promote even drying. Uneven drying can lead to warping, cracking, or distortion.

Leatherhard is followed by bone-dry, when the piece is completely dry and ready for bisque firing. Properly timed leatherhard work helps ensure dimensional stability during firing and reduces common defects in the final piece. Related terms include greenware (the plastic stage), and bone-dry (the fully dry stage before firing).