The art of plastering is divided into two major fields of employ. Rendering is fundamental. A plaster apprentice first learns to tend, to prepare various binders such as gypsum, lime or cement into a workable plaster mix. As he progresses, he then learns how to “square” a room, establishing centerlines, benchmarks and grounds. His education culminates in mastering the art of rendering plaster; applying plaster in successive coats until he achieves a smooth and planar surface.
Many plasterers make a good living with rendering skills alone. However, once mastery of rendering has been achieved, a plasterer may progress on to run molding work. As is the case with all molding mediums, plaster molding is an art strongly allied to the field of architecture. A number of treatises, books and papers have been published from the Renaissance through the 20th century on the theory of molding design.