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.
Use
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 wall 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.
Mosaic technique
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 which have
a three dimensional quality such as vases.
The direct method suits small projects which are transportable.
Another advantage of the direct method is that the resulting
mosaic is progressively visible allowing for any adjustments
to tile placing or colors to.
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 direct onto fiberglass mesh. The mosaic
can then be constructed the right way up and then transported
to its final place. Large work can be done in this way, with
the mosaic being cut up for shipping and then put back together
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.
Mathematics
The best way to arrange various 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.
Digital imaging
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.
