Meanwhile… Glass

Following on from last week’s article about Diomo Glass, it seems fitting to focus on glass as an art medium.

Glass in its natural state is formed when a felsic lava (one that contains a lot of silica) cools too rapidly for crystals to grow – the result is a material such as obsidian. It is hard, brittle, and breaks to leave sharp edges that were used by prehistoric people as cutting tools. Other forms of natural glass can be formed by lightning hitting a quartz-sand beach.

Man-made glass is said to have originated in Mesopotamia around 3,500 BC, with Syria and Egypt being other dominant sites of manufacture for thousands of years. These early manufacturers kept their techniques strictly secret, although in the resign of Assyria’s King Ashurbanipal (c.650 BC), methods were written down on cuneiform tablets. By 70 AD, however, Pliny the Elder was suggesting contemporary sources in France, Spain, and Italy too (an idea borne out by a 2002 study of roman glassware isotopes!1).

Many cultures subsequently developed glass, including those in China, India, and arly techniques including: core forming (where molten glass is wound around a solid core, and allowed to cool before the core is removed); casting (pouring molten glass into a mould); and mosaic (fusing glass of different colours to form a swirl pattern). More advanced methods, such as glass blowing weren’t developed until 50 BC, when makers near Jerusalem discovered they could blow bubbles with glass.

There are now many many methods of glass production and decoration, both for utility and artistic purposes, but the rather humbling thing to remember is, if you visit the beach this summer, the sand you’re sitting on – containing the hard grains of quartz that don’t get broken down on their way to the sea – is the core material for glass.

Check out my Glass board on Pinterest:

1 “Pliny the Elder and Sr–Nd isotopes: tracing the provenance of raw materials for Roman glass production”. Degryse, P., & Schneider, J. 2008. Journal of Archaeological Science.

1,150-year-old glass flask found in China, but originally from Iran.

1,150-year-old glass flask found as part of a Tang dynasty burial in central China, but originally from Iran.
Part of Bristol Museum’s Chinese glass collection.

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