Precious but with a Heart of Dung?
We take for granted the clear glass of our windows, as well as the many bottles and jars we use and toss. However, ancient glass held a much higher value. The first glass appears in the Late Bronze Age around 1500 BCE in the Near East and Egypt.
Glass was intentionally given dark, rich colors, especially blue. People treated it like a precious stone such as lapis lazuli. Artisans made beads, amulets, and inlays of glass. In Near Eastern culture, they attributed magical powers to glass, such as healing and warding off the evil eye. Blowing glass wasn’t invented until around the first century CE. That meant Bronze Age glassworkers used a laborious technique to form vessels. They dipped a clay and dung base into molten glass and then trailed rods of different colors over it. Later they chipped the core away–very carefully! The Corning Museum has a fascinating video demonstrating this technique.
Mixing up Ancient Glass
Like modern glass, silica was the primary ingredient of ancient glass. For color, ancient people added compounds containing elements such as cobalt and copper (for blues), antimony and lead (for white and yellow) and manganese (purple and black). As with modern processes, soda provided the flux to lower melt temperature. Bronze Age workers derived their soda from the ash of salt tolerant plants that grew beside the desert or sea.
In Egypt, stone reliefs depict the Pharaoh making offerings of glass to the gods. Royal letters mention it as one of the precious gifts traded between the powerful rulers in the Mediterranean and Near Eastern kingdoms.
Analysis of glass by spectrometry reveals different “fingerprints” for Egyptian and Near Eastern glass, so, despite the lack of clear archaeological remains of a production center in the Near East, we know at least one existed. Ancient glass decays in wet environments, so only finding archaeological evidence in dry areas of Egypt doesn’t surprise archaeologists. Glass pieces found in Greece, the Levant, and the Ulu Burun shipwreck reveal one or other of these Egyptian and Near Eastern “fingerprints.” We do not know how many actual sites existed, but they seem to have stuck to one school of technique or the other.
For a more detailed discussion, photographs and videos, click here to read “Glass: Lapis Lazuli from the Kiln” in Ancient Near East Today.
For a post about the excavation of an Egyptian city where archaeologists found glass slag.