From bullet-proof glass to fine lead crystal too delicate to put in a dishwasher, from storing jam to spaceship components: glass is a remarkable substance.

Through millennia of research and development, humans have identified and engineered many properties to make it one of the most useful and diverse artificial materials on the planet. Perhaps the most amazing thing about it is, that even though it has been around for such a long time, its future is just as exciting as its past.

The Egyptians are often credited with discovering glass as we know it all the way back in about 3,500BC although contemporaneous evidence has been yielded in northern coastal Syria and Mesopotamia. Makes sense, you could say, seeing as these lands are surrounded by the principle raw material – sand. Most people now know that glass is formed by melting sand. But in some very early R&D the Egyptians found that adding soda ash (an alkaline) reduced the very high temperatures required to melt sand, thus easing production. Since then additives have been a key factor in R&D into glass.

It’s fair to assume that these early civilisations did not appreciate what they had on their hands. Earliest application seems to have been confined to decorative beads and it wasn’t until the Late Bronze Age some 2,000 years later that application started to accelerate (puts the pace of R&D today into context, doesn’t it?!).

OK, fascinating as it is we won’t get too bogged down in history: the Romans were keen glass makers and spread the technology across Northern Europe. And since then there have been expertise hubs that have fiercely defended their intellectual property. You think modern day patent wars can get nasty? The price put on disseminating glass-making knowledge by the Venetians was death!

Glass as a tool in other R&D

One of the most interesting aspects of glass is the role it can play as a tool in facilitating completely unrelated R&D. Here are a couple of examples of how glass has shaped our understanding of the world today in a huge way.

Glass played a major role in our understanding of the solar system. With the Copernican theory of the sun as the centre of the solar system being in direct conflict with the establishment view this was a hot topic in the early Seventeenth Century. Galileo’s experimentation with convex and concave lenses was to have historic impact. Inspired by work being done in Amsterdam, the professor from Padua applied his talents to the subject.  In the true iterative style of R&D he first produced a telescope that magnified by three, then eight and finally thirty three. Using this tool he discovered the satellites of Jupiter, the spots of the Sun, the phases of Venus and the hills and valleys of the Moon. His findings were to land in him in big trouble: heresy, imprisonment and a forced public renouncement of his findings. Nevertheless, glass had made its impact on human understanding of the universe.

Sir Isaac Newton famously used glass prisms to refract light, thus proving it consists of a spectrum of colour. While this is taken as a given now, it was ground-breaking in its time. There was stiff opposition from European philosophers who had subscribed to the Aristotelian view that pure light was colourless. His findings were published in Opticks – book regarded as one of the most significant in the scientific canon.

These two high profile examples are perfect for showing the leading role that glass has played as a tool in major scientific breakthroughs. It has of course played a supporting role in countless other experiments, from being the material of the humble test tube (it is virtually inert), to being a viewing window in hazardous environments (it is transparent and impermeable).

Direct applications of glass today

Today glass is everywhere and something of a paradox. How many materials can claim to be a bog-standard everyday consumer item – used in packaging for drinks and foodstuffs, and available to buy as a drinking vessel from Ikea and supermarkets for just a few pence; yet at the same time be a luxury item in the guise of fine lead crystal champagne flutes at price points far higher? How many materials have the diversity to adorn every building in the developed world as simple windows to let in light, but are also part of our heritage through magnificent stained glass in churches, centuries old? It is one of the building materials of choice in the construction industry as skyscrapers shoot up, particularly in China and the Middle East. On the South Bank in London, Europe’s tallest skyscraper is even called the Shard of Glass.

But we also balance it on the tips of our noses to help correct our vision.

From this diversity of use it is obvious that not all glass is the same and it is from a rich history of R&D that such a spectrum of properties has come about. Here we look at a few of the most interesting areas:

Strength

We do not necessarily associate strength with glass. The stuff we use every day in our homes will smash if knocked on the floor, shatter if exposed to rapid temperature variance and chip if caught on something. Yet through R&D past and present enormous strength can be bestowed upon glass. One technique is to experiment with the speed with which molten glass is cooled – specifically cooling the outside rapidly and inside more slowly. Another is to layer glass with polycarbonate plastic that can absorb shock. And a completely different approach is by manufacturing metallic glass – when molten alloy metals are cooled incredibly quickly leading to their atoms hardening in a glass-like non-crystalline structure. This leads to a tough substance in which cracks find it very difficult to propagate.

What does all this mean in the real world? We have Pyrex glass that can withstand high temperature without cracking. Bullet-proof glass – strong enough to live up to the name, and striking buildings clad in clear but super-tough glass.

glass with bullethole

Conductivity

Most people certainly would not associate glass with conducting electricity. Most glass is an electrical insulator. However it was discovered in the 1950s and 1960s that by using Sulphur (and other chalcogenide elements) in place of oxygen, when producing glass, that it can assume semi-conducting properties through temperature variations. Since then research in this field has led to rewritable CDs, PC Random Access Memory (RAM) and infra-red optical fibres. There are now a whole range of semiconducting glasses – sometimes called technical glass – that have a range of uses in the electronics industry. Continued research will have interesting potential for cognitive computing and reconfigurable logic circuits.

Additives

One of the strangest things about glass is that you can change its chemical composition, but it is still glass. It has even been likened to a pizza. Pepperoni, ham and pineapple, quattro formaggi – whatever ingredients you put on top, it’s still pizza. And it’s the same with glass – although we don’t think anyone has tried to make glass with prosciutto. The primary ingredient for glass as we know it is silica. However, in scientific terms, glass refers to any solid material that has a non-crystalline atomic structure. Hence the reference to metallic glass earlier. Some polymer thermoplastics and porcelain can also technically be counted as glasses too. Although for the purposes of this R&D exploration, we will stick to silica based glass.

So, silica is the main ingredient. The Egyptians discovered that adding soda ash eased the production process by lowering the temperatures necessary for melting it. And since then experimentation, trial and error and research and development have gone into discovering how the properties of glass can be changed through additives.

We have already touched upon lead crystal which is used to produce fine glassware. Here, lead oxide replaces the calcium additive in normal glass to produce a glass that has more dazzle and brilliance.

Colour is another quality controlled by additives. Bronze Age coloured beads and medieval stained glass are testament to a long tradition. Our home town of Bristol plays a role in the history of glass in this area with the Bristol Blue Glass company. Back in the 18th Century they championed cobalt oxide as an additive to give a brilliant blue colour. The company became renowned across Europe with its distinctive product before the glass industry went into a general long term decline. In the last 25 years there has been a revival and the company is once again making collectable glass.

But it is not just decorative qualities that can be altered through additives. Iron is used to absorb infrared energy which can be employed to produce filters to trap heat in film projectors. Lanthanum Oxide is highly effective at reflecting light making it useful for spectacle lenses. Boron is what is added to produce Pyrex Glass. This is a huge area of R&D.

When is glass not glass?

The name Lead Crystal is technically incorrect as it meets the definition of glass because its atoms bond in a non-crystalline structure – It’s still glass.  Dartington Crystal is a major employer within the South West, and one of the few remaining manufacturers of hand crafted crystal glass tableware in the UK, practicing traditional Swedish glass blowing techniques, as well as continually looking to innovate within their manufacturing processes. Sapphire Crystal on the other hand, although it looks like glass, is truly a crystal and therefore is not glass. Available naturally as a gem stone, it is also artificially manufactured for industrial use. Crystal is typically used in place of glass when its properties are required: the principle one of which is that it is virtually scratchproof. In fact on the Mohs Scale used to measure hardness, only diamond and moissanite are harder, meaning that nothing else can leave a scratch mark on it. For this reason, it has been a feature on high-end watches, high use barcode scanners in supermarkets and high pressure diagnostic scientific equipment. It is also likely to become increasingly prevalent in smartphones – it is significantly harder than the current standard Gorilla Glass (albeit for now it is heavier, more brittle and more expensive).

Green glass

We have talked enough about colour and glass already. Here we refer to glass’s role in environmental causes and sustainability. It is highly recyclable – glass bottles have a recycling rate of between 50% and 80%. It even helps in the production of new glass to include broken down old glass (known as cullets) which melts at a lower temperature than raw materials therefore reducing energy consumption.

Glass helps us save and generate energy. It plays a major part in the insulation of our homes: from double and triple glazing technology in our windows to the fibre glass insulation in our lofts. It is also one of the key materials in solar cell technology and wind turbines (through light-weight reinforcing glass fibres) in the production of renewable energy.

Glass and the future

We’ve examined at length what glass has offered us in the past and the present, but what about the future?

Glass Alliance Europe – a confederation of 19 national glass industries across the continent – imagines the potential application of glass in the coming years. They see it continuing to touch many aspects of our lives:

  • Medical – Augmenter mirrors that can assess the health of the person in front of them; jewellery that monitors heart rate and body temperature.
  • Architecture – Increasingly complex glass shapes to give architects greater license to design.
  • Sustainability – More efficient solar cell technology to boost green energy; better insulating technologies to further reduce heat loss; photovoltaic sunroofs to power electric vehicles.
  • Consumer experience – LED lighting in jewellery; drinking glasses that interact with the user; smart packaging that changes colour based upon temperature.

And beyond this glass is certain to continue being a key material in the future of aerospace, electronics, computing, optics and many other industries.

Want financial support for your glass work?

Glass is a fascinating and somewhat puzzling material. Despite being known about for at least five millennia scientists still cannot precisely explain what happens to sand between its molten and hard transparent phase when it appears to have both solid and liquid properties. So although so much about glass has been discovered there is still a lot of research and development to come.

If you are at the cutting edge of glass (metaphorically speaking), then you should explore how R&D tax credits can help support you in your work. It took the Egyptians 2000 years to work out you could do anything other than make decorative beads with glass. Thankfully things happen a lot quicker nowadays. So if you are experimenting with additives, cooling processes, application, or using glass in other R&D activity call an expert at ForrestBrown to see if you can qualify for R&D tax relief that could recover as much as one third of your qualifying costs.

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