Pottery molds are molds which are designed for use with ceramics. People can use pottery molds to create uniform sets, like matching bowls and plates, and molds can also be custom-created for specific projects. Ceramic and art supply often sell molds which are suitable for use in pottery. Commercial pottery manufacturers also use specialized pottery molds in the mass production of ceramic products. People who do not wish to purchase their own can often find a set for common use in an open ceramics studio or ceramics lab.
For pottery on the wheel, molds known as bats can be used to create standardized shapes. People throw pottery directly on the bat, using the mold to ensure that the pottery shape is even and regular. While it is possible to throw very standardized pottery shapes on the wheel with experience, bats can eliminate some of the guesswork, and be very valuable for people producing high volumes of pottery. Bats are also useful for perfectionists who are struggling with attempts to make a coordinating pottery set for a friend or client.
Drape molds, on the other hand, are pottery molds which are designed for use with flat sheets of clay. To utilize this kind of pottery mold, potters roll out clay very fine, often with a slab roller, creating a sheet of clay which can be draped inside the mold and pressed to conform with the shape of the mold, ensuring that the resulting piece will be even and crisp. When using drape molds, it is important to allow for shrinkage, as the clay will decrease in size significantly as it shrinks.
Both types of pottery molds can be purchased from companies which specialize in the production of molds. It is also possible to order custom pottery molds, such as molds with a stamped design which will transfer to the finished pottery. Some potters like to make their own molds, selecting a particularly fine potted piece and using it as a template for a mold which can be used again and again. Potters can also make variations on a standard mold by inserting things like leaves, coins, or abstract shapes into the mold before the clay, ensuring that these objects will leave distinctive impression in the clay.
Classically, pottery molds are made from plaster, both because plaster is a good material for making molds, and because plaster is highly absorbent. When clay is placed in a plaster mold, the plaster wicks away moisture from the clay, encouraging it to dry very quickly. Once the clay is partially dried, it can be gently teased away from the mold and allow to dry completely before being bisqued, glazed, and fired.