It started with…

…one of the most intriguing terms I’ve ever heard. ‘Supercooled liquid’ (OK, call me a geek, but I really think its a ‘cool’ term – see what I did there?). Anyway. Supercooled liquid is a scientific term for one of the most common materials now used by humankind – what you and I call ‘glass’.

In basic science we learnt that if you take a solid piece of any material and heat it enough, it’ll liquefy. If you heat it further, it’ll eventually turn into a gas. For example, imagine an ice block (solid) that melts into a puddle of water (liquid). If you heat the water, eventually it’ll convert to steam (gas). Reverse this process by cooling stuff, and gas converts to liquid, which then converts to solid on further cooling. These processes are true for most materials in our universe.

But not glass.

Frozen in time…

Transparent-Glass-Hourglass-Timer-10-Minutes-Time-Gift-Sandglass-Sand-Clock-Timers-Sand-Timer-Home-Decoration.jpg_960x960It’s as if the hot molten glass was sloshing around and when it was cooled suddenly, it solidified into whatever shape the liquid was in. And this is, in fact, exactly how glass is made.

You start with sand, ordinary sand. Yes, the same stuff on our beaches. Heat the sand until it turn into a really thick liquid. And when it cools, it doesn’t turn back into gritty grains – it changes its form and becomes something between a solid and a liquid. Glass is schizophrenic – its exhibits some behaviours of a solid and others of a liquid. Hence ‘supercooled liquid’.

So by just heating and then cooling, we turn opaque grainy sand into smooth transparent stuff that we use everywhere. Quite the makeover. Hot molten glass can be poured into moulds to make bottles, glasses, dishes, etc. Sheet glass, also called ‘float glass’, is made by pouring the molten glass onto molten tin metal. The molten glass floats on the molten tin and when cooled forms the perfectly flat sheets that are used in windows and on table-tops.

Murano 2
Glass art from Murano

Special glasses are achieved by the addition of specific chemicals or meterials. For borosilicate glass, used to make those useful Pyrex® oven-proof dishes, add boron oxide. Bulletproof glass is made up of thin layers plastic sandwiched between thin sheets of glass.

For coloured glass (aka ‘stained’ glass), add different metallic compounds to achieve different colours. Used to make the windows in old European churches. Also used in the lovely art form of glass-blowing in which a blob of molten glass is taken onto one end of a blow-pipe, and the glass-blower can then blow it into all kinds of weird and strange and beautiful and colourful shapes. Think Murano near Venice, one of the most famous venues of this art form.

Violently natural…

Obsidian arrow-head

Glass is also formed by nature using some of her most violent tools – volcanoes, meteorites, lightning. When molten lava is suddenly cooled, like when it flows into water, it forms a type of glass called obsidian. Also known as Dragonglass, obsidian is very useful for killing White Walkers (Haven’t seen “Game of Thrones”? Really?).

Meteor strikes, with insanely high pressures and temperatures of impact, created one of the oldest types of natural glass. Not recently, thankfully. Scientists have named this type of glass ‘impactite’. Creative name.

FulguriteThen there’s lightning, which sometimes strikes sand, and melts it into fragile glassy tubes also known as ‘petrified lightning’. Doesn’t it look like a piece of coral? Beautiful.

A million uses…

Our technologically modern world wouldn’t be what it is without glass. Extremely hard and one of the most durable materials known to us – it is said that glass takes a million years to decompose. And yet, peculiarly, so brittle. Its uses are innumerable, often invisible and sometimes surprising.

We drink out of glasses – even if made of plastic or metal. Glasses made of ‘glass’ were earlier called tumblers but the term is now more about the function than the material. My personal favourite is probably the wine glass made of crystal, which is made by adding lead to glass, sometimes as much as 40%. Ever wonder why crystal glasses are so heavy? Now you know.

Global interner
Optical fiber network around the world

You’re reading this article on your smartphone, tablet or computer which connects you to the Internet. As of today over 1,200,000 kilometers of optical fiber cables, most of it on sea beds, are the ‘data pipes’ that transfer digital data all across the world. In comparison the circumference of the earth is 40,000 kilometers. These cables are made of bundles of glass fiber, each fiber strand as thin as a hair, carrying data at close to the speed of light. They can carry much more data, for longer distances, than old-fashioned copper cables, and are much lighter. They also last much longer. 

After traversing the world on optical fibers this digital data lands wirelessly on your smartphone, which has a magical touchscreen so sensitive to your touch and yet rugged enough to withstand many drops. Corning Inc. (the same guys who invented Pyrex®) had been experimenting with a special chemically-strengthened glass since 1960. In 2005, a consumer electronics company named Apple came knocking at their door looking for a thin toughened glass to use as the screen for a new device they were launching. Yup – the iPhone. The rest is history, and Gorilla Glass is now used in over 5 billion devices around the world.

Let’s go back a few centuries. It was the invention of the optical telescope by Galileo Galilei in 1609 that gave birth to modern astronomy. He made his own glass lenses to assemble his first telescope with a 3x (!) magnifying power and started a journey of scientific discoveries that has revealed to us so many wonders of our universe. 

Dark Side of the Moon
(You know this music album, right?)

Later that same century, in 1666, Sir Isaac Newton founded modern opticsby using a glass prism to split a beam of white light into its constituent seven colours, the famous VIBGYOR colours of the rainbow. About 300 years later this experiment would inspire one of the most iconic music album covers ever…

Environment friendly and safe…

Glass has many, many uses, practical as well as aesthetic. Throughtout history it has enabled many discoveries and innovations. And today it is one of the  bedrocks of our modern, technology-driven world.

Bottle Sweating

But for me the wonder of glass is much more mundane. Since it is chemically inert, you can use glass to store almost anything without the risk of chemical reactions or heat deformation. More importantly, humble glass is one of the most environmentally friendly of materials. Use it to make containers which can be used and re-used forever. Even if it breaks the broken glass is recyclable without any loss of clarity or purity.

Unfortunately in the past 50 years plastic has replaced glass for most purposes as it cheaper, lighter and unbreakable. We are the ‘plastic generation‘. It’s economics, plain and simple! Plastic means less breakage and losses during transportation. Lesser weight means more product can be transported, with lower fuel costs. Single-use plastics in our homes cause way too much pollution.

We have now begun seeing the damage that plastic is causing our planet and our bodies. Plastics don’t truly degrade, they break down into microscopic particles that contaminate our water, soil and air. Worse, as plastics break down, they also leech toxic chemicals  into the environment.

Glass is supercool…

We already have the solution to plastic pollution. A material that is 100% recyclable, completely non-toxic and multi-use. Something that needs a little more care but holds tremendous rewards for our planet. Its time for us to do a rewind.


Supercool. But coolest when its a chilled bottle of beer!







One thought on “Glass

  1. Loved it Geet!!
    Not just because it took me back to Engineering Materials 101 back in College, but because you just made glass ‘super-cooler’ by adding the Geet quotient!
    Looking forward to clinking some super-cooled liquid with some chilled liquid in it , with you guys soon!
    Looking forward to your next one soon!


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