Friday, 19 November 2021

Ancient Glass

Glass is common today. In ancient times it was reserved for kings and the elite, valued only slightly lower than silver and gold and about the same as precious gemstones. Archaeologists have found glass beads dating to as early as the third millenium BCE. Glazes and technology date earlier still. In the Late Bronze Age, 1600 to 1200 BCE, the use of glass took off. Glass of those times was opaque and saturated with color. The source of the silica was crushed quartz pebbles, not sand. Ancient glass makers used ash of desert plants, which contain high levels of salts such as sodium carbonate or bicarbonates. The plants also contain lime, calcium oxide, that made the glass more stable. They also added materials to color glass, such as cobalt for dark blue, or lead antimonate for yellow.
Egypt is favored as the birth place of glass making. But by the 1980s, thinking changed to the Near East after loads of glass was found at Nuzi, a Late Bronze Age provincial town in modern-day Iraq, thought to date from the 1500s BCE.

The raw glass blocks were Egyptian, based on the concentration of trace metals.
Glass was a cornerstone of international trade. In the early 1980s, divers found off a sunken vessel from the 1300s BCE off the coast of Turkey. The Uluburun shipwreck contained a load of colored glass — 175 unfinished blocks, called ingots, for glassworking. Most of the ingots were cobalt-colored deep blue, but purple and turquoise ingots were also found.