The Value of Transparency

Once you start looking for it, it can be quite staggering to realise just how much of our modern world is, quite literally, built on glass. The stuff is manufactured in vast quantities, coating our windows, lights, screens, skyscrapers and countless other uses. Some argue that it is even responsible for the entire development of the world, particularly in the west, as we know it; it’s almost a wonder we take it for granted so.

Technically, out commonplace use of the word ‘glass’ rather oversimplifies the term; glasses are in fact a family of materials that all exhibit the same amorphous structure and behaviour under heating whilst not actually all being made from the same stuff. The member of this family that we are most familiar with and will commonly refer to as simply ‘glass’ is soda-lime glass, made predominantly from silica dioxide with a few other additives to make it easier to produce. But I’m getting ahead of myself; let me tell the story from the beginning.

Like all the best human inventions, glass was probably discovered by accident. Archaeological evidence suggests glassworking was probably an Egyptian invention in around the third millennia BC, Egypt (or somewhere nearby) being just about the only place on earth at the time where the three key ingredients needed for glass production occured naturally and in the same place: silica dioxide (aka sand), sodium carbonate (aka soda, frequently found as a mineral or from plant ashes) and a relatively civilised group of people capable of building a massive great fire. When Egyptian metalworkers got sand and soda in their furnaces by accident, when removed they discovered the two had fused to form a hard, semi-transparent, almost alien substance; the first time glass had been produced anywhere on earth.

This type of glass was far from perfect; for one thing, adding soda has the unfortunate side-effect of making silica glass water-soluble, and for another they couldn’t yet work out how to make the glass clear. Then there were the problems that came with trying to actually make anything from the stuff. The only glass forming technique at the time was called core forming, a moderately effective but rather labour-intensive process illustrated well in this video. Whilst good for small, decorative pieces, it became exponentially more difficult to produce an item by this method the larger it needed to be, not to mention the fact that it couldn’t produce flat sheets of glass for use as windows or whatever.

Still, onwards and upwards and all that, and developments were soon being made in the field of glass technology. Experimentation with various additives soon yielded the discovery that adding lime (calcium oxide) plus a little aluminium and magnesium oxide made soda glass insoluble, and thus modern soda-lime glass was discovered. In the first century BC, an even more significant development came along with the discovery of glass blowing as a production method. Glass blowing was infinitely more flexible than core forming, opening up an entirely new avenue for glass as a material, but crucially it allowed glass products to be produced faster and thus be cheaper than pottery equivalents . By this time, the Eastern Mediterranean coast where these discoveries took place was part of the Roman Empire, and the Romans took to glass like a dieter to chocolate; glass containers and drinking vessels spread across the Empire from the glassworks of Alexandria, and that was before they discovered manganese dioxide could produce clear glass and that it was suddenly suitable for architectural work.

Exactly why glass took off on quite such a massive scale in Europe yet remained little more than a crude afterthought in the east and China (the other great superpower of the age) is somewhat unclear. Pottery remained the material of choice throughout the far east, and they got very skilled at making it too; there’s a reason we in the west today call exceptionally fine, high-quality pottery ‘china’. I’ve only heard one explanation for why this should be so, and it centres around alcohol.

Both the Chinese and Roman empires loved wine, but did so in different ways. To the Chinese, alcohol was a deeply spiritual thing, and played an important role in their religious procedures. This attitude was not unheard of in the west (the Egyptians, for example, believed the god Osiris invented beer, and both Greeks and Romans worshipped a god of wine), but the Roman Empire thought of wine in a secular as well as religious sense; in an age where water was often unsafe to drink, wine became the drink of choice for high society in all situations. One of the key features of wine to the Roman’s was its appearance, hence why the introduction of clear vessels allowing them to admire this colour was so attractive to them. By contrast, the Chinese day-to-day drink of choice was tea. whose appearance was of far less importance than the ability of its container to dissipate heat (as fine china is very good at). The introduction of clear drinking vessels would, therefore, have met with only a limited market in the east, and hence it never really took off. I’m not entirely sure that this argument holds up under scrutiny, but it’s quite a nice idea.

Whatever the reason, the result was unequivocal; only in Europe was glassmaking technology used and advanced over the years. Stained glass was one major discovery, and crown glass (a method for producing large, flat sheets) another. However, the crucial developments would be made in the early 14th century, not long after the Republic of Venice (already a centre for glassmaking) ordered all its glassmakers to move out to the island of Murano to reduce the risk of fire (which does seem ever so slightly strange for a city founded, quite literally, on water).  On Murano, the local quartz pebbles offered glassmakers silica of hitherto unprecedented purity which, combined with exclusive access to a source of soda ash, allowed for the production of exceptionally high-quality glassware. The Murano glassmakers became masters of the art, producing glass products of astounding quality, and from here onwards the technological revolution of glass could begin. The Venetians worked out how to make lenses, in turn allowing for the discovery of the telescope (forming the basis of the work of both Copernicus and Galileo) and spectacles (extending the working lifespan of scribes and monks across the western world). The widespread introduction of windows (as opposed to fabric-covered holes in the wall) to many houses, particularly in the big cities, dramatically improved the health of their occupants by both keeping the house warmer and helping keep out disease. Perhaps most crucially, the production of high-quality glass vessels was not only to revolutionise biology, and in turn medicine, as a discipline, but to almost single-handedly create the modern science of chemistry, itself the foundation stone upon which most of modern physics is based. These discoveries would all, given enough time and quite a lot of social upheaval, pave the way for the massive technological advancements that would characterise the western world in the centuries to come, and which would finally allow the west to take over from the Chinese and Arabs and become the world’s leading technological superpowers.* Nowadays, of course, glass has been taken even further, being widely used as a building material (its strength-to-weight ratio far exceeds that of concrete, particularly when it is made to ‘building grade’ standard), in televisions, and fibre optic cables (which may yet revolutionise our communications infrastructure).

Glass is, of course, not the only thing to have catalysed the technological breakthroughs that were to come; similar arguments have been made regarding gunpowder and the great social and political changes that were to grip Europe between roughly 1500 and 1750. History is never something that one can place a single cause on (the Big Bang excepted), but glass was undoubtedly significant in the western world’s rise to prominence during the second half of the last millennia, and the Venetians probably deserve a lot more credit than they get for creating our modern world.

*It is probably worth mentioning that China is nowadays the world’s largest producer of glass.

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