Arrangement of small fragments of stones, colored glasses, golden pieces, or other materials, fixed on walls or pavements and depicting an image or making an abstract pattern. The technique of mosaic is a decorative art that reached a peak during the Byzantine period of Christian art.
The traditional mosaics consist of marbles and stones in the scale of black and white (sometimes together with red) or other materials which were available in nature. At the beginning, in the Antique age, mosaics were used only as pavements, as stones on the ground, a floor material. During the first centuries of Christianity, during the Byzantine period, the Church took over the mosaic technique. The Byzantine technique with walls done with mosaics was new in the fifth and sixth centuries. In the basilicas of Ravenna, Italy, the Byzantine mosaic masters worked with entire walls of mosaic made up of small pieces of colored glass and gold, tesserae, affixed to mortar. Tesserae, a term derived from a Greek word meaning “four-sided,” is the standard for mosaic pieces. Before being divided, the tesserae are part of a blown flat glass in the form of a “pizza plate” (in today’s terminology). Smalti is the technical term for the brilliant, opaque-colored crystalline material fused with glass.
The new materials that the Byzantine mosaic masters introduced were colored glass and gold. These materials offer a wider and more intense color scale than the marble mosaics. The tesserae-mosaic is a kind of color material that is mixed optically (on the retina of the eye). The material interacts in a special way with vision and light. The surface is shiny, hard, and reflective. Glass pieces are shiny and slightly irregular in pure colors and gold. The gold picks up light and reflects gold light back into the room. The entire composition involved the setting of mosaic pieces at different angles so as to reflect light as effectively as possible. Seen from a distance, the singular mosaic pieces appear to model figurative forms. In the present time, this technique is considered as somewhat comparable to the compositions of the Neoimpressionist painters of the 1880s. Thus, the mosaic masters possessed knowledge of the eye’s ability to apprehend color mixing. They also acquired understanding of the changes colors underwent with distance and also of the interaction of light and material.
The images in the Byzantine basilicas are often constructed from contrasting colors. Red stands against green in costumes and clothing designs. A pair of red shoes usually meets green grass. When two contrasting colors meet, there is an increase in both colors. Another approach in the sixth century, used by the mosaic masters to avoid changes in color, was to apply a contour line between two colors. This contour line prevents the colors from spilling over into each other. Instead, the colors are depicted without visible distortion. The gold mosaic primarily represented the halos of the holy figures but was also placed in the background. The subject of the church mosaics was to serve the spirit, not the body. In the images, all suggestions of movement have been avoided; instead, an “eternal existence” is shown. The combined effect in the milieu of the church is a glittering, multicolored immaterial curtain. The material, the light, and the surface interact.
By studying the mosaics, it is possible to see how the mosaic masters applied the tessera pieces with skill and knowledge of color and what happens optically at a distance. The mosaic masters mixed colors optically for entire large areas of color. For instance, in order to give a lawn its various shades of green and thus get a nuanced and living surface, the mosaic pieces were placed against each other in turquoise, green, and gray-green for the purpose of combining and so forming the greenness of the grass. Gold mosaic was also used – in addition to create areas of gold color and point out important details – to mix the colors in larger fields.
When viewing a mosaic wall, the changes of the material from matte to shiny can be discerned. How the mosaic is reflected depends on its angle against the wall. Two pieces of the same inherent color placed with different tilt angles result in that each one will have a different appearance. This effect results from light projecting and reflecting different information to the eye. Reflection is also dependent on how the light strikes the mosaic pieces, on whether the tesserae are made of glass (shiny) or marble (often matte), on the viewing angle, and on how the viewer moves in the room. No movement of the subjects or the motifs on the walls is discernible. The hues are perceived as stable and unchangeable, and unaffected by nearby colors. But with the movement of the viewer in the room, and the changes in the eye’s view, the mosaic walls are transformed from matte to shiny, and back again. Through the mosaic, the viewer participates in the process of change.
In the present time, it is possible to find the impact of late Antique mosaics in Sweden, for example. In 1919, the Swedish artist Einar Forseth made a study trip to Italy. The architect Ragnar Östberg designed the Stockholm City Hall in 1923, and Einar Forseth was appointed to create the Golden Hall. Forseth chose mosaic for his commission. The Golden Hall is thus covered with more than 18 million glass and gold mosaic pieces. The mosaics depict Swedish historical figures and interpret certain events in the Swedish history, but the technique, the imaging, and the colors are in Byzantine style with its origins in Ravenna. Besides the Stockholm City Hall, the Byzantine technique can be seen in an underground station situated in Rinkeby, a suburb of Stockholm. In his adornment from 1975, the artist Nisse Zetterberg used mosaic in gold, in the tesserae technique, applied with different angles to the background. The mosaics depict patterns, symbols, and runes inspired by the Viking age, once found in the Rinkeby excavations.