“People who live in glass houses shouldn’t throw stones” is a timeless proverb. Today’s saying?
“People who own foldable smartphones shouldn’t wear long nails, forget phone cases, bend their phones too much or clean their displays with any cloth” is the current advice for those who bought foldable phones.
Really though, this advice will soon be obsolete, as companies are working to make ever thinner, ever stronger glass.
Let’s look at ultra thin glass, the most exciting innovation in the world of smartphones and a material that will change how the future looks.
In this in-depth explanation of ultra-thin glass, we’ll delve into material science, the history of exciting glass and which companies are now racing to make the world’s thinnest glass – and what they plan to do with it.
How thin is ultra thin glass?
Ultra thin glass is any glass that’s under 1 mm thick but most ultra thin glass manufacturers are racing to get the material down to its smallest possible size. Schott, for example, announced they made ultra thin glass that’s just 25 μm. How thin is 25 microns? The company is saying that’s thinner than a human hair but for you to actually visualize it, think of saran wrap and cling film. Indeed, most commercial cling film is just 25 μm thin.
World’s thinnest glass, discovered by accident
Impressive as 25 microns sounds, the world’s thinnest glass is actually much thinner! Discovered by accident by scientists at Cornell University and Germany’s University of Ulm, the world’s thinnest glass is just two atoms thick. It’s so thin that its individual silicon and oxygen atoms are visible only via electron microscopy.
That ultra-thin glass is now recognized by the Guinness Book of World Records.
Is ultra thin glass actually glass or plastic?
Speaking of cling film, many would think UTG is plastic but no, UTG is actually glass. The confusion comes from a few years ago, when YouTuber JerryRigEverything did a durability test on the Samsung Galaxy Z flip phone. Back then, he thought Samsung was using a hybrid plastic polymer with a little bit of glass mixed in their “ultra thin glass” formula.
The company responded and reassured customers that the material is actually glass through and through – just that the screen is, indeed, protected from scratches and damage with a thin layer of plastic.
How do they make ultra thin glass?
Thanks to the famous show How It’s Made, we have a good look into the fabrication process of ultra thin glass. The video below is a great intro and shows how ulta-thin glass was made but scroll on, because we’ll help you down this fascinating rabbit hole.
Did you know that flexible glass is an alleged lost invention from the time of the reign of Tiberius Caesar in AD 14-37?
The history of ultra thin glass
According to a story from Pliny the Elder, the inventor of flexible glass (so-called vitrum flexile) brought a drinking bowl made of the material before Tiberius Caesar.
During a test aimed at breaking the bowl, witnesses saw that instead of shattering, the bowl only suffered a dent. As described by Petronius, the inventor promptly fixed the bowl using a small hammer he had conveniently stored in his toga.
The inventor, claiming to be the sole person knowledgeable about the manufacturing process, made an oath to this effect. What happened? Well, things didn’t really work out for him.
Tiberius, concerned that the presence of such a valuable material as glass might diminish the value of gold and silver, ordered the inventor to be executed.
How ultra-thin glass is made today
Fortunately, we’ve come a long way from that, though indeed, the stuff might be actually more valuable than gold.
Nowaday, most bendable or foldable glass is ultra-thin glass, and the manufacturing processes are fascinating.
A few months ago, Samsung also posted a video showing how UTG (ultra-thin glass) is made in their facilities – but scroll on, because we have plenty of more in depth looks at the manufacturing process.
Just like regular glass panes, ultra-thin glass is usually produced by melting raw materials, pouring the molten glass onto a flat surface where it spreads out and floats to form a thin sheet, cooling it down, and then shaping and finishing it for various applications.
The exact manufacturing process may vary depending on the specific requirements of the glass and the manufacturer. Advanced techniques, such as fusion draw methods, can also be employed to produce ultra-thin glass. However, the fundamental idea is to melt the glass, form it into a thin sheet, cool it down, and then shape and finish it for its intended applications.
To provide ultra-thin glass with extra strength and shatter resistance, each company has a specific process.
In the case of Schott, for example, they explain in a YouTube video that they use both one-step chemical strengthening and a two-stage process for certain glasses that contain lithium. Here is a look at the process to strengthen rigid cover glass, a method similar to strengthening UTG.
As you can see in the video explanation above, the raw glass is placed in a hot salt bath that contains potassium ions. Given that the glass already contains numerous sodium ions, a chemical reaction occurs where the potassium ions replace the sodium ions on the surface of the glass. Due to the larger size of potassium ions, this substitution creates a compressive stress on the surface.
However, as the potassium ions are unable to penetrate deeply into the glass, the compressive stress gradually diminishes with depth. Consequently, an internal tensile stress is generated, opposing the initial compressive stress.
What is ultra thin glass used for?
Several companies have been involved in the development and production of ultra-thin glass. While it is difficult to provide an exhaustive list, some of the major names include Corning, the renowned glass and materials science company you’re probably familiar with from your phone screen, as well as Schott AG, who is also known to consumers thanks to smartphones.
Schott AG was kind enough to send us a sample of their ultra-thin glass, a version of which is used in foldable phones. While it’s not as thin as the ultra-thin glass used in the actual phones and up to 2 to 3 times thicker than that application, the sample we put to the test did show just how strong ultra thin glass is and made us imagine some exciting possibilities.
According to Schott, their latest version of ultra-thin glass (UTG) is capable of bending radii below 1 mm after processing. In this video, they claim that this glass, thinner than a human hair, can withstand up to 300,000 bends before breaking.
As a company with a lot of skin in the foldable phones arena, Samsung is also involved in ultra thin glass production.
Samsung has incorporated UTG technology in their Galaxy Z Fold and Galaxy Z Flip series of smartphones. These devices feature foldable displays that rely on the flexibility and durability of UTG to withstand repeated folding and unfolding without compromising the screen quality. As you might remember, not all of their devices were very durable in the hands of regular users, though the situation has improved rapidly in recent years, as they refined their process.
In 2022, Samsung revealed that their ultra thin glass is now just one third of the thickness of human hair.
What is the thinnest glass you can get?
Are you curious about seeing the thinnest glass possible but don’t want to spend north of a thousand dollars for a foldable phone?
The good news is that ultra-thin glass can be bought even outside of company use.
You can find ultra-thin glass in packs of a few sheets of ultra thin glass as thin as 0.3 milimeters on sites like Alibaba if you want to do experiments.
Where you can buy ultra-thin glass
If you just want to satisfy your curiosity or have a simple project in mind,, MaterialSampleShop sells a single sheet of ultra thin glass that’s just 50 microns thick for about $20. Be careful though, that’s one online store where you’ll want to keep adding cool stuff to your cart!
Also read: How to Get Your Own “Vantablack” Art Piece
We hope this answers all your curiosities about ultra-thin glass but, if you have more questions, do let us know in the comments and we’ll update this guide.