Mosaic
|  | A small part of The Great Pavement, a Roman mosaic laid in AD 325 at Woodchester, Gloucestershire, England. |
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 | Cave canem mosaics ('beware of the dog') were a popular motif for the threshold of Roman villas. |
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| Located in Tustin, California, this contemporary opalescent glass mosaic by David Ascalon depicts events from the Old Testament. |
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Mosaic is the
art of decoration with small pieces of colored glass, stone or other material. It may be a technique of
decorative art, an aspect of
interior decoration or of cultural significance as in a
cathedral. Small
tiles or fragments of pottery (known as
tesserae, diminutive
tessellae) or of colored glass or clear glass backed with metal foils are used to create a pattern or picture.
Mosaic was used across the ancient world for domestic interior decoration. Mosaics of the
4th century BC are found in the Macedonian palace-city of
Aegae, and they enriched the floors of
Hellenistic villas, but mosaic floors are particularly associated with
Roman dwellings from Britain to
Dura-Europas. Splendid mosaic floors distinguished luxurious Roman villas across north Africa. In Rome, Nero and his architects used mosaics to cover the surfaces of walls and ceilings in the
Domus Aurea, built
64 CE.
With the building of Christian
basilicas in the late
4th century, wall and ceiling mosaics were adapted to Christian uses. The greatest development of Christian mosaics unfolded in the
Byzantine empire including its outpost the
Exarchate of Ravenna and its territories in
Sicily, and in its rival
Venice, where mosaic encrusts the exterior and interior of
St Mark's. In Western Europe, the demanding techniques of fresco replaced the even more labor-intensive techniques of mosaic.
Islamic architecture used mosaic technique in intricate geometric designs. The process is known as
zillij in
North Africa and
qashani further east. Some of the best examples of Islamic mosaics were produced in
Moorish Spain and are still visible at the
Alhambra. The craft has also been popular in the
Eastern Orthodox tradition and in Russia.
A modern example of mosaic is the
Museum of Natural History station of the
New York Subway.
Some spectacular modern mosaics are the work of
modernisme style architects
Antoni Gaudí and
Josep Maria Jujol, for example the unique mosaics in the
Park Güell in
Barcelona.
Ravenna (Italy) is known world-wide as the Capital of Mosaic on account of its unique artistic heritage. A few miles from Venice and Florence, Ravenna means a fantastic tour to discover a city rich of artistic treasures such as S. Apollinare Nuovo, Basilica di San Vitale, Mausoleo di Galla Placidia.
There are three main methods - the direct
method, the indirect method and the double indirect method.
Direct method
The direct method of mosaic construction involves directly placing (gluing) the individual
tesserae onto the supporting surface. This method is well suited to surfaces that have a three dimensional quality, such as vases.
The direct method suits small projects that are transportable. Another advantage of the direct method is that the resulting mosaic is progressively visible, allowing for any adjustments to tile colors placement.
The disadvantage of the direct method is that the artist must work directly at the chosen surface, which is often not practical for long periods of time. It is unsuitable for large scale projects. Also, it is difficult to control the evenness of the finished surface. This is of particular importance when creating a functional surface such as a floor or a table top.
A modern version of the direct method, sometimes called "Double Direct," is to work directly onto fiberglass mesh. The mosaic can then be constructed with the design visible on the surface and transported to its final location. Large work can be done in this way, with the mosaic being cut up for shipping and then reassembled for installation. It enables the artist to work in comfort in a studio rather than at the site of installation.
South African mosaic artist Stevie Godson is widely acclaimed for her works using this method.
Indirect method
The indirect method of applying tesserae is often used for very large projects with repetitive elements. Tiles are applied upside-down to an adhesive backing paper, and later transferred onto walls, floors or craft projects. This method is most useful for mosaics with simple or geometric patterns, solid blocks of color, and extremely large projects. Mosaic tabletops are usually made using the indirect method, as it results in a smoother and more even surface.
Double indirect method
The double indirect method is often used when it is important to see the work during the creation process as it will appear when completed. The tesserae are placed face-up on a medium (often adhesive-backed paper or sticky plastic) as it will appear when installed. When the mosaic is complete, a similar medium is placed atop it. The piece is then turned over, the original underlaying material is removed, and the piece is installed as in the indirect method described above.
Both indirect and double-indirect methods are often performed in sections, allowing extremely large projects such as murals to be completed off-site and transported to their destination without large trucks being needed.
The best way to arrange variously shaped tiles on a surface can lead to complicated mathematical problems - see
tessellation for details.
Roger Penrose is a mathematician who has worked with tiling problems - see
Penrose tilings.
The artist
M.C. Escher was influenced by Moorish mosaics to begin his investigations into
tessellation.
A mosaic in
digital imaging is a plurality of non-overlapping images, arranged in some
tessellation. A
photomosaic is a picture made up of various other pictures (pioneered by Joseph Francis), in which each "
pixel" is actually another picture, when examined closely.
A tile mosaic is a
digital image made up of individual
tiles, arranged in a non-overlapping fashion, e.g. to make a static image on a shower room or bathing pool floor, by breaking the image down into square pixels formed from ceramic tiles (a typical size is 1 inch by 1 inch, as for example, on the floor of the
University of Toronto pool, though sometimes larger tiles such as 2 by 2 inch are used). These digital images are coarse in resolution and often simply express text, such as the depth of the pool in various places, but some such digital images are used to show a sunset or other beach theme. Obviously digital images expressed in ceramic tile are of very low resolution.
Thus apart from the artistic value (i.e. the work of Robert Silvers,
Ed Chapman and others who use mosaicing creatively), the mosaicing is usually considered an
artifact to be filtered out, through
interpolation by
demosaicing.
