Blue

EGYPTIAN Vessel (aryballos) in the Form of a Hedgehog, 664–525 BC

Vessel with Relief Decoration, AD 1–99

Eye of Horus (Wedjat) Amulet, 1550–332 BC

ALTHOUGH THE TERM faience has, since the Middle Ages, been associated with colorful tin-glazed earthenware from Europe, the rich blues of Egyptian faience constitute a far more ancient, unique ceramic production. Faience is perhaps the earliest engineered material. Crushed quartz or sand, lime, and alkali were combined to create a whitish core with a fine white ground layer, to which was then applied a soda-lime-silica glaze tinted with copper to form a brilliant blue (see pages 22, 27, 34, 38, 43, and 125). In one variation of this technique, called efflorescence, the glazing materials are incorporated into the body itself. As water evaporated during firing, the copper components migrated to the surface, fusing to form the blue glaze. Shapes were often formed in molds made by casting the shapes of objects such as vessels (see pages 33, 43, 92, 97, and 110), metal finger rings (see page 6), or amulets (see pages 46, 112, 137, 157, and 164). Blue-glazed quartz objects dating from as early as 3100 BC have been found in ancient Nubia. Egyptian techniques for the production of faience (see pages 23, 45, 64, 82, and 107) and glazed steatite (soapstone) (see page 137) were evidently adapted to produce a brilliant, translucent blue over white quartz, perhaps intended to simulate the appearance of precious gemstones. The early-nineteenth-century Harvard University–Boston Museum of Fine Arts expedition to Kerma in the Sudan excavated hundreds of small glazed stone artifacts such as beads (see page 21) but also several extraordinary objects of unparalleled scale and execution (see pages 45, 46, and 154). Kerma was apparently a center for the production of faience and glazed stone. Sculptural objects such as a magnificent, nearly half-life-size lion body (see page 19) and a large scorpion appeared at this site in ancient Egypt (see page 45). These objects were carved from white quartzite and glazed with a brilliant, translucent blue that, when fired, fused to the stone in heat intense enough to temporarily slightly soften the stone itself.

Another blue pigment, Egyptian blue, first produced around 4500 BC, is considered the earliest synthetic pigment (see pages 52 and 54). Like Egyptian faience, it contains silica, an alkali, and copper as a colorant, but with the addition of calcium, often from limestone. Small, intricately shaped objects of similar composition have been excavated in both ancient Mesopotamia and Egypt (see pages 11 and 120). These objects were fashioned from pâte de verre (also known as copper frit or molded lapis lazuli) and called uknû merku in Mesopotamia, or hsbd iryt in ancient Egyptian (see pages 46 and 138). Already exported to Minoan Crete by 2500 BC, this ubiquitous pigment, known for its beauty and immutability, has been found in Luxor, in Pompeii, at the Parthenon, and as far away as Libya, Uzbekistan, London, and Norway.

In composition, Egyptian blue mimics the rare mineral cuprorivaite, which is seldom found in nature and was only identified in 1938. The synthetic form was widely used in antiquity, but its use diminished precipitously after the fall of the Roman Empire until interest in it revived in the twentieth century. Today, it is valued by artists for its rich cerulean color, but it is also appreciated by both art historians and scientists for its highly unusual characteristics. Under certain infrared wavelengths of light, it emits a characteristic luminescence (see page 48 detail under normal light [l], and showing traces of Egyptian blue pigment fluorescing bright white under infrared light [r]). This characteristic allows its presence to be identified even when only traces are present—a technique used to reconstruct original color schemes on ancient art. Researchers have recently discovered that it can be broken into nanosheets—sheets so thin that thousands would fit across the width of a human hair. In addition, the distinctive visible radiation emitted by Egyptian blue under certain lighting conditions provides researchers with opportunities to use it in fields as diverse as laser technology, biomedical imaging, telecommunications, and security systems.