Term: Plaster
**History and Types of Plaster:**
– Plaster has a rich history dating back 7,000 years, with early uses in the Middle East, Egypt, and Europe.
– Types of plaster include clay plaster, gypsum plaster (Plaster of Paris), lime plaster, and cement plaster.
– Clay plaster, made of clay, sand, water, and plant fibers, has been used globally since ancient times for interiors and decorative purposes.
**Manufacturing and Applications:**
– Plaster is manufactured as dry powder forms like gypsum, lime, and cement, which are mixed with water before application.
– Plaster is used for wall and ceiling coatings, decorative elements, medical casts, dental models, and fresco painting.
– Lime plaster, for example, is used for frescoes and wall surfaces, setting through a chemical reaction with carbon dioxide.
**Specific Plaster Types and Uses:**
– Gypsum plaster (Plaster of Paris) is used for making casts, statues, and toys due to its hardening properties with water.
– Lime plaster is common for lath and plaster construction and frescoes, providing smooth surfaces for painting.
– Cement plaster is applied to masonry for smooth surfaces and fireproofing, with heavy versions for exterior applications.
**Artistic, Medical, and Fire Protection Applications:**
– Plaster is widely used in art for sculptures, reliefs, molds, and architectural details.
– In medicine, plaster supports broken bones, creates dental models, and aids in radiotherapy immobilization.
– Plaster is crucial for fire protection, releasing water vapor to slow fire spread and providing insulation to structural elements.
**Safety, 3D Printing, and Miscellaneous Uses:**
– Safety concerns include burns from exothermic setting and hazards from silica or asbestos inhaled during work.
– 3D printing utilizes gypsum plaster with water for intricate designs and rapid prototyping in various industries.
– Miscellaneous uses include joint compounds, exterior finishes like stucco, Tadelakt waterproof plaster, and historical plaster work styles like Yeseria.
Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of buildings, while "render" commonly refers to external applications. The term stucco refers to plasterwork that is worked in some way to produce relief decoration, rather than flat surfaces.
The most common types of plaster mainly contain either gypsum, lime, or cement, but all work in a similar way. The plaster is manufactured as a dry powder and is mixed with water to form a stiff but workable paste immediately before it is applied to the surface. The reaction with water liberates heat through crystallization and the hydrated plaster then hardens.
Plaster can be relatively easily worked with metal tools and sandpaper and can be moulded, either on site or in advance, and worked pieces can be put in place with adhesive. Plaster is suitable for finishing rather than load-bearing, and when thickly applied for decoration may require a hidden supporting framework.
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.