I recently bought a new chair mat for my office, and upon putting the chair mat in place, I found myself scared to use it. My brain said, mm-mm, nope, not gonna happen. Danger. Danger, Will Robinson. I couldn't overcome the fear of this mat, because the mat is made of glass. And experience has taught humans for hundreds of years that stepping on glass is dangerous. And that leads us to today's topic: tempered glass, and how I can roll my now fancy office chair over my very fancy tempered glass mat and not fear for my life. I'm Mimi Fotz, and this is Hello from the Van. So let's talk about this tempered glass. Tempered glass, sometimes called toughened or safety glass, is glass that is quickly cooled during production and is then four to five times stronger than annealed glass. Now, if that was all a lot that didn't make a lot of sense, I totally get it. Let's break down those big words. To anneal something means to cool it slowly. So annealed glass, like the vases in your cupboard, is glass that has been cooled slowly, normally in a box appropriately called an annealer. Now we need to talk about the word temper. Temper is one of those silly words in English that has multiple meanings. It has one definition as a noun and a completely opposite definition as a verb. The first definition is a state of emotion. That's the noun. If someone has a temper, they're easy to anger or to experience heightened emotion. That is not the definition that we're working with today. The glass is not angry, okay? The second definition of the word is the verb, and it means to strengthen by adding to, or to soften by adding to. I know those seem like opposite words. Let me explain. If we tell someone to temper their expectations, we're telling them to soften them. If we tell someone to temper their glass, we're telling them to strengthen it. English is inherently confusing. When we talk about tempering glass, we are talking about strengthening it through adding an extra stress to quickly cool the glass from its molten or liquid state to its solid state. Let's go back. Glass, and thus windows in one form or another, have been around that we know of since at least the first century. Glass is made by heating quartz or sand until it's molten, then cooling it slowly or annealing it, there's that word again, into whatever shape you want or can. This glass tends to break into sharp angled pieces due to its slow annealing process and can be inherently dangerous. It wasn't until around the year 1660 that a man named Prinz Rupert of Rhine brought a discovery to a group of artists and scientists. This group of artists and scientists wasn't just your ragtag run-of-the-mill group. They were a group called the Royal Society, and they had tasked themselves with finding and discovering new inventions and science and art and things that just needed to be discussed and researched. The item that Prince Rupert, sorry, mm-hmm, Prince Rupert of Rhine brought was a small drop of glass with a tail. We accordingly, to this day, call this invention Prince Rupert's Drop. But then it was just a new thing that he brought. It didn't have a name. Prince Rupert brought, sorry, Prince Rupert brought this glass teardrop to the Royal Society to show them its incredible strength. Because at its thickest part, it is incredibly strong. You can hit it with a hammer or press it with hydraulic press and it won't break. But if you tap the very thin, fragile tail, the entire thing will explode. This was fascinating to this group of scientists. They were fascinated by it and they wanted to research it. But how was it made? Well, this was the first iteration of tempered glass that we know of. These drops of glass were made by dropping molten glass into a bucket of cold water. There's that quick cooling. This quick cooling is essential for tempered glass. We know this now, but they didn't know it then. So it was very exciting. Now, well, we call it Prince Rupert's drop. He didn't actually invent it. We discovered later on that he's just responsible for bringing it to this group of scientists and saying, hey guys, look at this cool thing I found. He didn't invent it. But he is the one that brought attention to it. And that attention was critical to getting it to the rest of the world. In 1874, a Frenchman named Francois Barthelemy Alfred Royer de la Bestie was granted a patent for a process that involved tempering glass to increase its durability. Three years later, Frederick Siemens was credited with developing a compressed glass process. By the 1900s, different processes for tempering glass and laminating glass had spread throughout the world, and it all goes back to Prince Rupert of Rhine taking Prince Rupert's drops to the Royal Society in 1660. And this led to one of the coolest discoveries. It was done by a French chemist in 1903. His name was Edward Benedictus, and he was working in a lab when he accidentally dropped a beaker that had previously contained a liquid nitrate solution. The solution had created a layer of plastic on the inside of the beaker that prevented it from shattering. Instead, it just cracked in several spots without breaking. Benedictus had a eureka moment and discovered that he now could contain things in beakers and not worry about them shattering and breaking and going everywhere. Six years later, in 1909, he patented this discovery. This was known as laminated safety glass. It was used in World War I to construct windshields for airplanes, aviation glasses, and coverings for the eye holes and gas masks. By 1920, laminated glass was being used in the banking industry to provide an added layer of protection between bank tellers and their customers. So when you go to the bank and there's that glass between you and the teller, yeah, that's been a thing for over a hundred years. And then in 1948, an American named Harold McMaster founded a company called Permaglass, where he commercialized the glass tempering technology. You see, he'd been working for Ford as a physicist and had come up with this process of tempering glass. And rather than hand it over to Ford, he chose to start his own company. It's not just that his glass is tempered, it's that it breaks into small pieces and could be shaped. A very big plus for the automotive industry. And that brings us to today. What is the current strongest glass in the world? Would you be surprised to know that after all of these hundreds of years, the strongest form of glass is still Prince Rupert's drop? That's still the strongest form of natural-tempered glass that we have. It's strong enough to break a hydraulic press. But again, if you crack its fragile tail, it will burst into pieces. But hey, much like Achilles and Prince Rupert, we all have our weaknesses. If you're looking for synthetic or man-made glass, the strongest glass in the world is a product developed in China in 2025 called AM3. And it's basically sheets of synthetic diamond. It's relatively new and has been shown in research to be incredibly strong and also has the ability to conduct electricity. This makes it a huge potential option for solar panels. The craziest part about the synthetic carbon material? It has been shown in testing to be able to scratch diamonds. This is a big deal, as diamonds are the hardest naturally occurring substance in the world. Let's circle back to that glass office mat that started this whole thing. How tough is that? I did some reading, and the mat that I have that I'm currently sitting on can support at least a thousand pounds of weight without bowing or cracking. And if all of this talk of tempered glass has you suddenly worried about your car windows, you can do a quick experiment to see the tempering on the windows. It's pretty simple. If you have a pair of polarized sunglasses, now they can't just be any sunglasses, they must be polarized. With a pair of polarized glasses, look at the back window and you will discover what looks like a waffle pattern. This is how you can tell that it's tempered glass. Pretty neat, huh? Now before we go, you might have a couple more questions, and one of those is probably why does annealed glass shatter into deadly sharp shards and tempered glass fall into small, dull pebbles? Well, it has to do with the transfer of energy. Remember that first law of thermodynamics from last week where energy can't be created or destroyed, only transferred? Annealed glass doesn't have a lot of energy or tension, and tempered glass has a lot of tension. Basically, in tempered glass, the reason it's so strong is because it has potential energy. And when that energy is released, it does it in a fantastic way, resulting in a break across the entire surface of the piece of glass. If you've ever cracked a vase and it hasn't shattered, that's because there's just not as much potential energy or tension in an annealed piece of glass. So to wrap up today's episode, why can I sit on this very cool piece of glass and not worry about it breaking? Well, it's because a lot of very smart people and a man named Prince Uru Petabraim figured out that if you cool some glass fast enough, it becomes incredibly strong. And with that, I'm Mimi Fat, and this has been Hello from the Van.