[1][2] Parts that are typically made by plaster casting are lock components, gears, valves, fittings, tooling, and ornaments.
For instance, talc or magnesium oxide are added to prevent cracking and reduce setting time; lime and cement limit expansion during baking; glass fibers increase strength; sand can be used as a filler.
For example, if the casting includes reentrant angles or complex angular surfaces then the rubber is flexible enough to be removed, unlike metal.
Discarded plaster can be recycled by grinding but care must be used since silica dust causes permanent lung damage.
[1][2] Plaster mold casting is used when an excellent surface finish and good dimensional accuracy is required.
[3] The major disadvantage of the process is that it can only be used with lower melting temperature non-ferrous materials, such as aluminium, magnesium, zinc and sometimes copper alloys.
If these factors are not closely monitored the mold can be distorted, shrink upon drying, have a poor surface finish, or fail completely.