Plastermold

A plastermold, also called a plaster mold, is a gypsum casting mold made from plaster of Paris used to reproduce a form in ceramics, sculpture, or metalworking. Plaster’s fine grain and porous structure enable high-detail reproduction and rapid setting, making plastermolds well suited for short runs and prototyping. In ceramics, they are commonly built in two halves around a master model to create a removable cavity.

Construction involves preparing the model, applying a release agent, and applying multiple coats of plaster to build a strong shell. The mold may be reinforced with fabric for stability, especially for larger pieces. After curing, the model is removed and the two halves are separated to allow casting or forming.

Applications include slip casting and press molding in ceramic practice; in metal casting, plastermolds are used for plaster-mold casting of low-melting alloys, with the mold sometimes destroyed to retrieve the casting. The technique can reproduce fine detail and smooth surface textures, but the plaster is brittle, susceptible to moisture, and not suitable for high-volume production or high-temperature metals.

History and scope: Plastermold techniques have a long history in decorative arts, sculpture, and early industrial prototyping, and remain in use for art casting, education, and certain crafts. Practitioners must manage shrinkage, drying, and mold wear to maximize life.