Mosaics

I

Introduction

Mosaics, works of art of surface decorations, composed of variously colored small pieces of glass, stone, ceramics, or other materials. Although mosaic decoration is most frequently found on floors and wall and ceiling surfaces, closely set colored components, or tesserae, may also be applied to sculptures, panels, and other objects.

II

Materials and Techniques

In ancient times mosaics were a form of floor decoration made of small pebbles and later of cut or shaped pieces of marble, hard stone, glass, terra-cotta, mother-of-pearl, and enamels. The shaped pieces, in the form of small cubes, are called tesserae or tesselae. The tesserae are embedded in plaster, cement, or putty to hold them in place. Techniques for arranging the components in a design include opus tesselatum, simple geometric patterns; opus vermiculatum, small stones arranged in patterns of curved lines, including pictures of objects; opus musivum, mosaic decorations of walls; and opus sectile, a pattern composed of larger stones of varied shapes.

Knowledge of mosaic techniques is mostly derived from direct examination of specific examples; damaged mosaics in İstanbul provide explicit information. Walls to be covered with mosaics received a triple coat of plaster. The first layer, of lime, sand, and brick dust, was applied over the masonry to produce a smooth surface. The intermediate layer—1.25 to 5 cm (0.5 to 2 in) thick—was made of lime, sand, and chopped straw. This surface was scratched or tooled to receive the third coat, called intonaco, of plaster of lime and marble dust, which was applied over a small area, as much as could be completed in one day. It was then painted in detail in true fresco and immediately set with colored cubes to match the painted surface.

To make tesserae, thin slabs of marble or of colored stone were cut into strips, which were then cut or broken into cubes. Molten glass was tinted in a wide range of colors with metal oxides and then poured on a flat surface such as a marble slab to form a disk of colored glass; this was scored with a sharp tool and broken into strips and cubes. Gold and silver cubes were produced by gilding glass slabs of pale shades with gold or silver leaf. The surface was then covered with a frit (thin layer of powdered glass) and reheated in a furnace to secure the gold or silver between the layers of glass; the slab was then scored and broken into small cubes. The cubes were set into the painted intonaco one at a time, with resulting deliberate irregularities of the surface. These variations in surface planes catch the light and impart vitality to the finished wall. In many backgrounds the cubes are angled downward in rows, with space between the rows; when viewed from a distance this gives the appearance of a solid background. The stone and glass tesserae in mosaics are relatively stable materials, so that many ancient mosaics have survived with the same brilliance that was part of their original conception.

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III

Pre-Christian Mosaics

Mesopotamia, in the 4th-3rd millennium bc, developed a type of mosaic composed of slender cones of baked clay with some base ends painted red, black, and white. These were embedded in mud brick walls to create a decorative protective coating in geometric patterns, perhaps derived from textile or matting materials. A large section of a Sumerian wall of half-columns (early 3rd millennium bc) from Erech (Uruk), decorated with these patterns, is preserved in the Staatliche Museen, West Berlin. See Mesopotamian Art and Architecture.

In Crete (Kríti) and on the Greek mainland in the Bronze Age (1600-1000 bc), water-worn pebbles were used to decorate floors. Pebble mosaic floors have been discovered throughout the Hellenic Greek world from the 6th to the 4th century bc, with notable examples in Athens, Corinth, Delphi, Olympia, Olynthus, Pella, Assus, and Tarsus. The polychrome pebble mosaics of about 300 bc at Pella in Macedonia are excellent examples of the use of subtle variations of color in water-polished stones to create beautiful figural compositions, often of light figures against a dark background, with outlines in either lead or ceramic strips.

Before the end of the 3rd century bc, pebbles were in large part replaced with tesserae cut from stone and sometimes from glass. The smooth surfaces of cut cubes proved able to withstand wear and tear and also allowed the artisans to carry out designs in greater detail. The cubes could be cut to small size and packed closely together to create incredible detail, including realistic renditions of naturalistic scenes with human figures, animals, plants, and landscapes. See Greek Art and Architecture.

Mosaics from Pompeii show the introduction of Hellenistic mosaics in Italy. Polychrome scenes of the late 2nd and early 1st centuries bc are among the earliest mosaics at Pompeii. The famous Alexander mosaic from the House of the Faun depicts the Battle of Issus and is thought to be a copy of a lost Hellenistic painting of the 4th century bc; the mosaic, however, was most probably executed in the 1st century bc. The mosaics from Antioch (modern Antakya in Turkey) on the Orontes River date from the late 2nd into the 6th century ad . They show a predilection for polychrome figural mosaics. Mythological scenes are depicted with great realism in brilliant colors, including a Judgment of Paris, Narcissus, and the Labors of Hercules.See Roman Art and Architecture.

IV

Christian and Islamic Mosaics

In Early Christian mosaics of the 4th to the 6th century, decorative borders frame human figures, animals and birds, and frequently hunting scenes. In the Church of Santa Costanza in Rome, built about ad350, the vaults carry mosaics of vine scrolls and geometric designs that enclose figures of pagan origin. See Early Christian Art and Architecture.

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