Editing Plaster (section)

==Applications==
===In decorative architecture===
{{Main|Stucco|Plasterwork}}<gallery>
File:John Cranch - Plasterer - Google Art Project.jpg|Early 19th Century plasterer at work – painting by [[John Cranch (English painter)|John Cranch]] (1751–1821)
File:Gachbori kashan.jpg|19th century [[stucco]] plasterwork from [[Borujerdi House|House of Borujerdies]] in [[Kashan]], [[Iran]]
File:Face plaster cast application.jpg|Face plaster casting [[bandage]] application
</gallery>Plaster may also be used to create complex detailing for use in room interiors. These may be geometric (simulating wood or stone) or naturalistic (simulating leaves, vines, and flowers). These are also often used to simulate wood or stone detailing found in more substantial buildings.

In modern days this material is also used for [[dropped ceiling|false ceiling]]. In this, the powder form is converted in a sheet form and the sheet is then attached to the basic ceiling with the help of fasteners. It is done in various designs containing various combinations of lights and colors. The common use of this plaster can be seen in the construction of houses. Post-construction, direct painting is possible (which is commonly seen in French architecture), but elsewhere plaster is used. The walls are painted with the plaster which (in some countries) is nothing but calcium carbonate. After drying the calcium carbonate plaster turns white and then the wall is ready to be painted. Elsewhere in the world, such as the UK, ever finer layers of plaster are added on top of the [[drywall|plasterboard]] (or sometimes the brick wall directly) to give a smooth brown polished texture ready for painting.

===Art===
{{See also|Plaster cast}}
[[File:sch op 8.jpg|thumb|Example of a stenciled plaster design]]

Mural paintings are commonly painted onto a plaster secondary support. Some, like Michelangelo's [[Sistine Chapel ceiling]], are executed in [[fresco]], meaning they are painted on a thin layer of wet plaster, called [[intonaco]]; the pigments sink into this layer so that the plaster itself becomes the medium holding them, which accounts for the excellent durability of fresco. Additional work may be added ''a secco'' on top of the dry plaster, though this is generally less durable.

Plaster (often called [[stucco]] in this context) is a far easier material for making [[relief]]s than stone or wood, and was widely used for large interior wall-reliefs in Egypt and the [[Near East]] from antiquity into Islamic times (latterly for architectural decoration, as at the [[Alhambra]]), Rome, and Europe from at least the Renaissance, as well as probably elsewhere. However, it needs very good conditions to survive long in unmaintained buildings – Roman decorative plasterwork is mainly known from [[Pompeii]] and other sites buried by ash from [[Mount Vesuvius]].

Plaster may be cast directly into a damp clay mold. In creating this ''piece molds'' (molds designed for making multiple copies) or ''waste molds'' (for single use) would be made of plaster. This "negative" image, if properly designed, may be used to produce clay productions, which when fired in a kiln become [[terra cotta]] building decorations, or these may be used to create cast [[concrete]] sculptures. If a plaster positive was desired this would be constructed or cast to form a durable image artwork. As a model for stonecutters this would be sufficient. If intended for producing a bronze casting the plaster positive could be further worked to produce smooth surfaces. An advantage of this plaster image is that it is relatively cheap; should a patron approve of the durable image and be willing to bear further expense, subsequent molds could be made for the creation of a wax image to be used in [[lost wax casting]], a far more expensive process. In lieu of producing a bronze image suitable for outdoor use the plaster image may be painted to resemble a metal image; such sculptures are suitable only for presentation in a weather-protected environment.

Plaster expands while hardening then contracts slightly just before hardening completely. This makes plaster excellent for use in molds, and it is often used as an artistic material for casting. Plaster is also commonly spread over an armature (form), made of wire mesh, cloth, or other materials; a process for adding raised details. For these processes, limestone or acrylic based plaster may be employed, known as stucco. {{Citation needed|date=October 2008}}

Products composed mainly of plaster of Paris and a small amount of [[Portland cement]] are used for casting sculptures and other art objects as well as molds. Considerably harder and stronger than straight plaster of Paris, these products are for indoor use only as they degrade in moist conditions.
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===Funeral processes===
Plaster is used by many morticians and funeral home directors to recreate destroyed tissue, reconnect severed limbs to corpses, and to fill wounds sustained during the incident that caused the death.{{cn|date=June 2022}} -->

===Medicine===
Plaster is widely used as a support for broken bones; a bandage impregnated with plaster is moistened and then wrapped around the damaged limb, setting into a close-fitting yet easily removed tube, known as an [[orthopedic cast]].

Plaster is also used in preparation for [[radiotherapy]] when fabricating individualized immobilization shells for patients. Plaster bandages are used to construct an impression of a patient's head and neck, and liquid plaster is used to fill the impression and produce a plaster bust. The transparent material [[poly(methyl methacrylate)|polymethyl methacrylate]] (Plexiglas, Perspex) is then vacuum formed over this bust to create a clear face mask which will hold the patient's head steady while radiation is being delivered.{{Citation needed|date=October 2008}}

In dentistry, plaster is used for mounting casts or models of oral tissues. These diagnostic and working models are usually made from dental stone, a stronger, harder and denser derivative of plaster which is manufactured from gypsum under pressure. Plaster is also used to invest and flask wax dentures, the wax being subsequently removed by "burning out," and replaced with flowable denture base material. The typically acrylic denture base then cures in the plaster investment mold. Plaster investments can withstand the high heat and pressure needed to ensure a rigid denture base. Moreover, in dentistry there are 5 types of gypsum products depending on their consistency and uses: 1) impression plaster (type 1), 2) model plaster (type 2), dental stones (types 3, 4 and 5){{Citation needed|date=October 2008}}

In orthotics and prosthetics, plaster bandages traditionally were used to create impressions of the patient's limb (or residuum). This negative impression was then, itself, filled with plaster of Paris, to create a positive model of the limb and used in fabricating the final medical device.

In addition, [[dentures]] (false teeth) are made by first taking a [[dental impression]] using a soft, pliable material that can be removed from around the teeth and gums without loss of fidelity and using the impression to creating a wax model of the teeth and gums. The model is used to create a plaster mold (which is heated so the wax melts and flows out) and the denture materials are injected into the mold. After a curing period, the mold is opened and the dentures are cleaned up and polished.

===Fire protection===
{{Unreferenced section|date=February 2020}}

[[File:Himeji Castle The Keep Towers.jpg|thumb|''[[Himeji Castle]]'', [[Himeji]], [[Hyogo Prefecture]], [[Japan]]]]

Plasters have been in use in [[passive fire protection]], as [[fireproofing]] products, for many decades.

Gypsum plaster releases water vapor when exposed to flame, acting to slow the spread of the fire, for as much as an hour or two depending on thickness. Plaster also provides some [[thermal insulation|insulation]] to retard [[heat]] flow into [[structural steel]] elements, that would otherwise lose their strength and collapse in a fire. Early versions of protective plasters often contain [[asbestos]] fibres, which since have been outlawed in many industrialized nations.

Recent plasters for fire protection either contain cement or gypsum as binding agents as well as mineral wool or glass fiber to add mechanical strength.
[[Vermiculite]], [[polystyrene]] beads or chemical expansion agents are often added to decrease the density of the finished product and increase thermal insulation.

One differentiates between interior and exterior fireproofing. Interior products are typically less substantial, with lower densities and lower cost. Exterior products have to withstand harsher environmental conditions. A rough surface is typically forgiven inside of buildings as dropped ceilings often hide them. Fireproofing plasters are losing ground to more costly [[intumescent]] and [[endothermic]] products, simply on technical merit. Trade jurisdiction on unionized construction sites in North America remains with the plasterers<!-- ?? -->, regardless of whether the plaster is decorative in nature or is used in passive fire protection. Cementitious and gypsum based plasters tend to be endothermic. Fireproofing plasters are closely related to [[firestop]] mortars. Most firestop mortars can be sprayed and tooled very well, due to the fine detail work that is required of firestopping.

===3D printing===
[[Powder bed and inkjet head 3D printing]] is commonly based on the reaction of gypsum plaster with water, where the water is selectively applied by the inkjet head.

===Gallery===
<gallery widths="170px" heights="170px">
File:Plaster - Putz in Pompeji.JPG|Plasterwork in [[Pompeii]] (79 AD)
Figure of a Woman MET DP329926.jpg|Figure of a woman; 5th century; painted plaster; height: {{convert|38.4|cm|in|abbr=on}}, width: {{convert|14.7|cm|in|abbr=on}}, depth: {{convert|9.6|cm|in|abbr=on}}; Metropolitan Museum of Art
Seated Voltaire MET DP105166.jpg|''Seated Voltaire''; by [[Jean-Antoine Houdon]]; 1778; plaster, tinted to imitate terracotta; overall: {{convert|35.6 × 14.6 x 20|cm|in|abbr=on}}; Metropolitan Museum of Art
Young girl identified as Anne Audéoud of Geneva (1776–1840) MET DP370292.jpg|Young girl; first modeled: 1779–1780; plaster; height: {{convert|36.8|cm|in|frac=2|abbr=on}}; Metropolitan Museum of Art
Nymph MET DP214931.jpg|Nymph; 1805–1810; plaster; height: {{convert|155.6|cm|ft|frac=4|abbr=on}}; Metropolitan Museum of Art
Édouard Baldus, Plaster Model of an Ornamental Oeil-de-Boeuf for the New Louvre, ca. 1856.jpg|Photo of a plaster model of an ornamental oeil-de-boeuf for the [[Nouveau Louvre|new Louvre]]; circa 1856; Metropolitan Museum of Art
Jupiter and the Sphinx MET DP242123.jpg|''Jupiter and the Sphinx''; 1868; tinted plaster; {{convert|116.8 × 112.1 × 60.3|cm|ftin|frac=4|abbr=on}}; Metropolitan Museum of Art
The Young Mother by Bessie Potter Vonnoh, c. 1896, plaster - Portland Museum of Art - Portland, Maine - DSC03949.jpg|''The Young Mother''; by [[Bessie Potter Vonnoh]]; circa 1896; plaster; [[Portland Museum of Art]] ([[Portland, Maine|Portland]], US)
</gallery>