Gypsum plaster, gypsum powder, or plaster of Paris, is produced by heating gypsum to about 120–180 °C (248–356 °F) in a kiln: [18] [13] CaSO 4 ⋅ 2 H 2 O ⟶ heat CaSO 4 ⋅ 1 2 H 2 O + 1 1 2 H 2 O ↑ {\displaystyle {\ce {CaSO4.2H2O {\overset {heat}{{}->{}}}{CaSO4.1/2H2O}+ 1\!1/2 H2O

Glossary of sculpting - Wikipedia

Gypsum plaster, [12] also known as plaster of Paris, [13] is a white powder consisting of calcium sulfate hemihydrate. The natural form of the compound is the mineral bassanite. [14] [15] Etymology [ edit ]

This article is about the type of building material and "Plaster of Paris". For other uses, see Plaster (disambiguation). Stucco plaster reliefs, such as this work at the Chateau de Fontainebleau, were hugely influential in Northern Mannerism. A plaster low-relief decorative frieze is above it. Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. [1] In English, "plaster" usually means a material used for the interiors of buildings, while "render" commonly refers to external applications. [2] The term stucco refers to plasterwork that is worked in some way to produce relief decoration, rather than flat surfaces. The surrounding forests of the new village of Economy provided straight grain, old- growth oak trees for lath. [10] Hand split lath starts with a log of straight grained wood of the required length. The log is split into quarters and then smaller and smaller bolts with wedges and a sledge. When small enough, a froe and mallet were used to split away narrow strips of lath. Farm animals provided hair and manure for the float coat of plaster. Fields of wheat and grains provided straw and hay to reinforce the clay plaster. But there was no uniformity in clay plaster recipes. Clay plaster is a mixture of clay, sand and water often with the addition of plant fibers for tensile strength over wood lath. Forms of plaster have several other uses. In medicine, plaster orthopedic casts are still often used for supporting set broken bones. In dentistry, plaster is used to make dental models by pouring the material into dental impressions. Various types of models and moulds are made with plaster. In art, lime plaster is the traditional matrix for fresco painting; the pigments are applied to a thin wet top layer of plaster and fuse with it so that the painting is actually in coloured plaster. In the ancient world, as well as the sort of ornamental designs in plaster relief that are still used, plaster was also widely used to create large figurative reliefs for walls, though few of these have survived.