Polished plaster is a term for the finish of some

plaster 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 "re ...

s and for the description of new and updated forms of traditional Italian plaster finishes. The term covers a whole range of decorative plaster finishes, from the very highly polished Venetian plaster and Marmorino to the rugged look of textured polished plasters. Polished plaster itself tends to consist of slaked lime, marble dust, and/or marble chips, which give each plaster its distinctive look. A lime-based polished plaster may contain over 40% of marble powder. Polished plaster is mainly used internally, on walls and ceilings, to give a finish that looks like polished

marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Marble is typically not foliated (layered), although there are exceptions. In geology, the term ''marble'' refers to metamorphose ...

travertine Travertine ( ) is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and even rusty varieties. It is formed by a p ...

, or

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

. Such plasters are usually applied over a primer and

basecoat Automotive paint is paint used on automobiles for both protective and decorative purposes. Water-based acrylic polyurethane enamel paint is currently the most widely used paint for reasons including reducing paint's environmental impact. Mode ...

base, from one to four layers. They are finished (

burnish Burnishing may refer to: * Burnishing (metal), plastic deformation of a surface due to sliding contact with another object * Burnishing (pottery) Burnishing is a form of pottery treatment in which the surface of the pot is polished, using a ...

ed) with a specialised steel

trowel A trowel is a small hand tool used for digging, applying, smoothing, or moving small amounts of viscous or particulate material. Common varieties include the masonry trowel, garden trowel, and float trowel. A power trowel is a much larger gas ...

to a smooth glass-like sheen. Polished plaster is usually sealed with a protective layer of wax.

Venetian plaster

Venetian plaster is a wall and ceiling finish consisting of

mixed with

dust, applied with a

spatula A spatula is a broad, flat, flexible blade used to mix, spread and lift material including foods, drugs, plaster and paints. In medical applications, "spatula" may also be used synonymously with tongue depressor. The word ''spatula'' derives f ...

in thin, multiple layers, which are then burnished to create a smooth surface with the

illusion An illusion is a distortion of the senses, which can reveal how the mind normally organizes and interprets sensory stimulation. Although illusions distort the human perception of reality, they are generally shared by most people. Illusions may oc ...

of depth and texture. Venetian plaster techniques include marmorino,

scagliola Scagliola (from the Italian ''scaglia'', meaning "chips") is a type of fine plaster used in architecture and sculpture. The same term identifies the technique for producing columns, sculptures, and other architectural elements that resemble inla ...

, and

sgraffito ''Sgraffito'' (; plural: ''sgraffiti'') is a technique either of wall decor, produced by applying layers of plaster tinted in contrasting colours to a moistened surface, or in pottery, by applying to an unfired ceramic body two successive laye ...

. When left un-burnished, Venetian plaster has a matte finish that is rough and stone-like to the touch. Un-burnished Venetian plaster is also very brittle and damages rather easily. When applied correctly, Venetian plaster can be used to create a highly polished, rock-hard, marble-like finish. Venetian plaster is especially useful on surfaces where marble panels could not be installed easily, and on surfaces that would be too expensive to have carved from real marble such as columns, corbels, and curved walls. Venetian plaster can be tinted, or colored using natural or synthetic colorants. The ability to tint Venetian plaster is especially helpful when a specific color of "marble" is desired, or when a color that does not exist naturally is wanted. Through the application of a top layer of wax sealant, Venetian plaster can also be rendered waterproof.

References

{{Reflist Building materials

Venetian plaster

See also

References