Murals, both historical and contemporary, are a unique form of artistic expression
Considered large pieces of public art created on an interior or exterior wall, some murals are removable, while others are painted directly on architectural structures. There are a variety of techniques artists use to produce murals, including fresco, oil painting and acrylic painting. Murals are often commissioned by building owners; however, some are painted spontaneously or in a community setting.
Fresco
The fresco technique, which has existed since prehistoric times and came to greatest prominence during the Middle Ages, is perhaps the most well-known painting style for murals. It consists of applying paint dissolved in lime water to wet plaster. As the piece dries, the paint becomes absorbed in the plaster, so that the materials are inseparable. According to the Fresco Techniques website, fresco is both the oldest and most environmentally sound style of painting. The secco technique, which consists of painting on plaster that is already dry, is closely related to fresco. However, it uses paint that is mixed with egg. The craft of binding pigments using egg is also called tempera painting. Faux fresco techniques are often used to capture the aesthetic qualities of fresco works without painting on plaster.
Oil
Oil painting, which came to prominence in the 17th century, is often used for the production of interior murals. Although most successfully applied to materials, such as canvas, wood and aluminum, this method can also work on cement surfaces if they are primed, finished, and exposed to a minimal amount of direct sunlight. According to the Golden Paints website, it is helpful to etch the mural design into the material before beginning to paint.
Acrylic
Acrylic paint is ideal for the creation of exterior murals, because it bonds well with masonry surfaces, including concrete and brick---not to mention it's also more impervious to the elements than oil-based paint. Acrylic paints can be applied by brush or by airbrush, depending on the surface and desired artistic effect. Golden Paints recommends using pigments with high ratings of lightfastness and permanency, so as to minimize degradation and fading. The article "Mural Painting," published in the November 2002 issue of "Just Paint" and reproduced on the Golden Paints website, lists the best acrylic pigments for exterior murals.
Trompe L'Oeil
Trompe l'oeil, a mural painting technique that gives the impression of three-dimensionality, can be produced using a variety of paint types. It began in Greece in the 4th century BCE, and was subsequently used in Roman cathedral murals of the Baroque period. The trompe l'oeil effect can be achieved by employing eye-level perspective, increasing sharpness and detail toward the front of the painting while allowing the background to remain blurry or impressionistic.
