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Annual Ravenscroft Lecture 2020 : “The Glass Age – from Antiquity to Ubiquity”

​Within the splendour of Middle Temple Hall, this year’s Glass Sellers’ Ravenscroft Lecture speaker, Paul Bingham, Professor of Glasses and Ceramics at Sheffield Hallam University, opened by asking his audience to stand and then sit only if they had an item of glass on their person. No worries, we all did: specs, wrist watch, mobile …!

Professor Paul took us through a most engaging and informative journey of glass – part chemistry (glass is a state of matter, not material, and is dependent on speed of cooling); part history (those Romans knew a thing or two, as recounted for us by Pliny the Elder, and set high standards of consistency of their light-blue bottles and centralised supply chain distribution); part future (under pressure, glass can lock-in CO2).

One of the early accomplishments of our Glass Sellers Company in the 1770s was to support George Ravenscroft in his project to develop clear lead crystal glass – a major milestone of the glass industry (and hence the name of our annual Lecture!). Professor Paul said it was only due to modern technology that we really know why lead crystal glass has such ‘brilliance’, particularly when the crystal is enhanced by cutting. It emits fluorescence, absorbing UV partly to release blue light.

Today’s world is increasingly turning to glass to provide answers to meet the demands of modern  applications: the flexible and toughened Gorilla and Willow glass in smart phones; a means to ‘absorb’ radioactive liquids and thus manage their storage more easily; and, towards the trivial end of the spectrum, the use of tiny glass beads in toothpaste that fill surface cavities that cause tooth sensitivity (don’t worry, the glass dissolves over time – that’s why you need to go on buying the same brand!)

But glass needs to clean up its own act. Glass furnaces need to reach temperatures upwards of 1,400 degC. And today they do that mainly using natural gas, a major cause of CO2. Paul sits on the advisory board of Glass Futures (with which our Master and the Company is closely involved). An initial, Government-funded initiative has recently been announced to find solutions with alternative power sources, eg hydrogen.

Professor Paul captured our attention in a most entertaining talk, following which Glass Sellers and their guests, together with many Masters and Clerks of fellow Livery Companies, enjoyed canapes and the age-old use of glass: to drink wine.

The most bizarre application of glass we heard during the evening? A passenger aircraft constructed in glass …. great views, but not for those challenged by vertigo!

PM William Knocker

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