This is a transcript of the Gastropod episode, Shatter-Proof: How Glass Took Over the Kitchen—And Ended Child Labor, first released on August 17, 2020. It is provided as a courtesy and may contain errors.
Correction: In an earlier version of the episode, we neglected to mention that American Pyrex is no longer made with borosilicate glass. It’s now made with tempered soda lime glass, which can actually shatter due to a rapid temperature change. You can still cook in it, but there’s a lot of fine print from the company about how to use it. We’ve updated the episode to include this information, but just in case you heard the first version—take note! We apologize for the oversight.
VICTORIA: I am a coloratura, Mr. Labisse, not a mezzo.
MONSIEUR LABISSE: Well, whatever you are, Andre Cassell should never have sent you here.
VICTORIA: He didn’t.
MONSIEUR LABISSE: You told me he was your agent.
VICTORIA: I lied. In spite of what you think, Mr. Labisse, there are some professions where practice DOES make perfect. [Sings sustained high note, his wine glass shatters.]
MONSIEUR LABISSE: What the hell was that?
NICOLA TWILLEY: Ah Julie Andrews. Pretending to be a man pretending to be a woman.
CYNTHIA GRABER: And still managing to shatter a wine glass with her gorgeous and super powerful voice, at least in the movie “Victor/Victoria.”
TWILLEY: But you know you cannot believe everything you see on the big screen. Like breaking a wine glass with just a perfect B flat.
ZOE LAUGHLIN: Yeah, I—it always had been a long held ambition to break wine glasses with sound.
GRABER: Some of you long-time Gastropod listeners might recognize that voice—Zoe Laughlin is none other than the star of our very first episode who said that mango sorbet tastes sublime on gold spoons.
TWILLEY: Hers is the voice that has inspired the purchase of a thousand golden spoons. Or at least a half dozen that we know about!
GRABER: Zoe is not just a spoon aficionado, she’s a materials scientist and director of the Institute of Making at University College London. And this episode we were super excited to talk to her again, not about gold spoons, but about glass.
LAUGHLIN: I mean, even though I sort of understand it on paper, everything about glass is still sort of extraordinary and mysterious, like just the fact that it’s transparent when pretty much everything else isn’t transparent is extraordinary.
GRABER: We have a lot of questions this episode. For one, how did something so seemingly delicate and breakable get to be so ubiquitous in the kitchen?
TWILLEY: And also how come you could never put a drinking glass in the oven, but you can cook in a glass dish?
GRABER: What does the invention of the bottling machine have to do with a beautiful stretch of protected sand dunes along the shores of Lake Michigan?
TWILLEY: Or with the rise of ketchup and Coca-Cola, and the abolition of child labor, for that matter?
GRABER: And more importantly can you actually shatter a wine glass using sound? Did Zoe pull it off?
TWILLEY: By the way, Cynthia, you might not have realized this but this episode is dedicated to your mother, glass maker extraordinaire! I have a piece of Tamah Graber glasswork on display in my house as we speak!
GRABER: And I have at least five pieces of fused and stained Tamah Graber glass. Mom, this one’s for you.
VINCE BEISER: What is glass? All glass everywhere in the world is, is at least 70% made of sand, that’s been melted down.
AINISSA RAMIREZ: And it’s mixed together in a way that the atoms don’t have any kind of order to them. And that’s what makes, gives rise to it being transparent.
TWILLEY: You’ve already heard from Zoe. Now it’s time to meet our other two intrepid glass enthusiasts who will be inducting us into the mysteries of this material this episode—Vince Beiser, journalist and author of a very enjoyable book called The World in a Grain: The Story of Sand and How it Transformed Civilization.
GRABER: And Ainissa Ramirez, materials scientist, and author of another totally delightful book called The Alchemy of Us, How Humans and Matter Transform One Another.
TWILLEY: Zoe, Ainissa, and Vince are all about glass.
BEISER: You cannot overstate how ubiquitous glass is and how important it is to the modern world in which we all live. I’m just looking around the kitchen where I’m standing. I’m seeing there are glass bottles, holding olive oil, there’s glass windows, there are glass fixtures around the glass light bulbs. It’s everything from, you know, salt shakers and eyeglass lenses, to things like 20 ton telescope lenses in the world’s most powerful telescopes. It’s in the fiber optic cables that connect us to the internet. Fiber optic cables are made literally of spun glass. So, really without glass, we wouldn’t have modern civilization.
GRABER: So we’ve established that this miraculous foundation of modern civilization is made of melted down sand with a few other ingredients thrown in. But to go back another step, and this is a strange question, but what is sand? And is all sand the same thing?
BEISER: The word “sand” means it’s just any small pieces: grains, right, of any hard substance. So sand can be anything. You know, it can be flint, it can be quartzite, anything, any kind of stone, but the most common form of sand, most of the sand in the world is quartz, which is silicon dioxide. And to make glass, that’s what you need. You need quartz sand, and you need especially high purity quartz sand.
TWILLEY: This seems very fortunate: you need quartz sand to make glass and that turns out to be what most of the sand is. Primarily because quartz is so hard that it just outlasts all the other rocks as they’re all getting ground down together.
GRABER: You do still have to clean the quartz sand up a bit and get out the last remaining impurities, and you have to add a few other ingredients to lower the melting temperature of quartz. And then you heat it up.
LAUGHLIN: You need a huge amount of heat. So well over 1700 degrees Celsius, which—what’s that in Fahrenheit? I mean, it’s over 3000 degrees Fahrenheit. But it’s bloody hot.
TWILLEY: Eventually the sand melts. And then it recongeals. And a weird thing happens when it turns into a solid again. Quartz is a crystal. But glass is not.
RAMIREZ: Well, it’s a weird structure because it’s not a crystal. Crystals are actually made up of atoms, they’re arranged like soldiers in rows, but glass is sort of like a picture of kindergarteners at recess. Atoms are all over the place. And so that’s what makes it unusual, but it’s that chaos in the arrangement of atoms that actually gives rise to it having the property of transparency.
GRABER: This is why some people have said—and you might have heard this before—glass isn’t actually a solid.
RAMIREZ: You know, that’s a little bit of a rumor within science. Some people think that it is, it’s still actually flowing and then you’ll see other research that says, no, that’s not the case. And some people will say, well, if you look at old windows, you’ll see that it’s thicker at the bottom. And then another set of scientists will say that well, it’s installed with the thicker end at the bottom. So it’s still a very heated debate, to be quite honest.
TWILLEY: But, wait for it … not as heated as you have to get sand to make glass.
GRABER: Thanks, dad.
TWILLEY: OK sorry, but that extreme heating process does beg the question: how did anyone figure out how to make glass in the first place?
BEISER: Yeah, so we didn’t, nobody even knows how glass was invented or, you know, where it first came from. But it has definitely been with us for thousands of years, man, at least four or 5,000 years. And we know that because we’ve found glass beads dating back 4,000, 5,000 years in what’s today, Iraq and Syria and the Caucasus regions.
LAUGHLIN: In many respects, you can imagine this is a society surrounded with lots of the raw material you would need, like plenty of sand, but also a glass in the form of fused sand would have occurred naturally, very, very rarely. When a lightning bolt strikes a desert, you get a structure formed where the sand has fused to form a solid amount of glass. And that would have been a really extraordinary object.
GRABER: So that’s how someone might have come across this wondrous substance in nature. But how did they figure out how to make it themselves from plain old sand?
BEISER: turns out if you mix it with stuff called flux, which is, it comes in a few forms, you can find it in seaweed or certain kinds of plants, that lowers the melting point. So the kind of standard theory is that probably somebody, you know, some folks on a beach somewhere in Phoenicia 5,000 years ago, built up a big old bonfire to keep themselves warm and, and mixed in accidentally some soda ash, some flux from plants or from shells or whatever else is on the beach. And got it hot enough to actually melt the sand into, into glass and into a sort of crude, cloudy glass.
TWILLEY: At first, people didn’t have a lot of control over what shape their recongealed sand ended up taking.
BEISER: And it definitely takes a step up in ancient Egypt. We know that around 1250 BCE that ancient Egypt under Ramses the Great had a pretty sizable glassworks. They were making perfume bottles, decorative items. But this wasn’t the glass like we think of it today. This was a long way from, you know, uniform pieces of neatly cut, transparent glass. This was like really cloudy, milky, weirdly shaped stuff. It was really pretty, but not really all that useful.
GRABER: After the ancient Egyptians come the ancient Romans. So what did they bring to the glass party?
BEISER: Oh, I’m so glad you asked. So the Romans picked up on this, you know, this art of making this, this pretty shiny stuff and really kind of took it to the next level.
LAUGHLIN: So, in fact, I’m going to do a little bit of sound down the microphone. Just TAP TAP. That’s my fingernail TAP against a tiny, I’d say it’s about a six centimeter high glass object. This is a tiny Roman vase made from glass, entirely from glass, that could have contained some sort of medicine, little potion. You couldn’t put more than a shot of liquid in it. It’s very small. It’s beautiful and perfect.
TWILLEY: Zoe’s Roman vase is adorable. It’s slightly skew, and the rim is wobbly, and it is a pale almost iridescent green.
LAUGHLIN: It’s a really lovely thing. And it’s incredible to think it is so old because it looks like it could have been made yesterday.
GRABER: The bottle is greenish, yes, but it’s also kind of transparent. And that was actually a major innovation that was discovered in a part of the Roman Empire that’s now in Egypt.
LAUGHLIN: In Alexandria, again, a particular port in Egypt, around 100 A.D., they learned that if you introduced manganese into the glass mixture, it made for a really clear glass.
BEISER: That gave them glass that was clear enough to have the world’s first glass windows. Again, these weren’t like really, you couldn’t really fully see through them the way that we can now, but you know, they were good enough that you could put one of these in a wall and all of a sudden you could get daylight into, into your house. Very nice. So the Romans got really good at that and they got so good at it that they started producing the world’s first glass tableware. Wine glasses that you could actually see through. And this became a hugely fashionable item for sort of the, you know, upper crust of Romans. All of a sudden, everybody wanted to have a clear glass so you could see the color of the wine you were drinking.
TWILLEY: Before wine might have been red or white, after, it could have been burgundy or more ruby toned, or golden straw colored versus almost perfectly clear.
GRABER: The next stop in our glass tour is also in Italy, in Venice. If only we could be reporting this in person.
BEISER: So basically Roman empire collapses, but glass making continues in Italy and becomes sort of the domain of a few very secretive guilds and families.
GRABER: The nobles of Venice prized the glassmakers’ work so much that they imprisoned them on an island called Murano so that they couldn’t take their glass secrets anywhere else. Murano glass is still really famous today.
TWILLEY: Just in fairness to the Venetians, yes, the glassmakers were not allowed to leave the city, but the whole being forced to live on this one particular island thing was more to do with the fact that their furnaces kept setting the rest of the city on fire.
GRABER: In the early days of Murano glass fame, the glass makers were particularly known for gorgeous white glass that looked like porcelain and the most perfect mirrors in all of Europe. A Murano mirror framed with silver was said to have been worth more than a painting by Raphael. And Venice really wanted to safeguard the secrets of the trade—in the 1500s a couple of glassmakers were apparently assassinated when they tried to escape to Germany.
TWILLEY: Back in those glorious days, finding a mirror that you could actually see your pores in was an impossibly rare thing—only kings owned such treasures.
GRABER: And it’s among these super famous highly protected glassmakers of Murano that another breakthrough occurred.
BEISER: So let’s talk about Angelo Barovier, a 15th century glass-making artisan. So he’s one of these guys. He comes from a long line of glassmakers and he set himself the task of creating truly transparent glass.
TWILLEY: Angelo brought home the purest of the purest sands, and then he played around in the forge, filtering it even more, and adding dashes of different chemicals. And he invented a truly clear, truly transparent glass called cristallo.
GRABER: The invention of cristallo led to beautiful wine glasses and other glass tableware—you could suddenly see the exact shade of your pale pink rosé in your gorgeous glass goblet even better than before. And glass started to become even more popular.
TWILLEY: And it wasn’t just seeing what you were drinking that would have changed the whole taste experience—
LAUGHLIN: Glass is inert, so it has no taste at all because it forms no reaction with any other material in your—on your tastebuds or with foodstuffs. I’ve had beer from a leather mug, which was quite an experience. Wooden vessels were very popular, leather vessels were popular, metal, pewter vessels were popular. And they all would have had a taste profile. So you would have been very conscious of the type of object you were drinking your drink out of and would have thought, actually, I like my stout from a wooden thing as opposed to a leather thing because I don’t like the taste of the tannins. Or sometimes the taste of the tannins might disguise the taste of the slightly overly ferment-y flavor of the drink or something. And it would add to the experience.
TWILLEY: When you drink beer or wine from a glass, on the other hand, you’re exclusively getting the taste of the beer or wine itself.
GRABER: So just like people could finally see their wine through these beautiful new glasses, they also could taste their wine much more honestly. It made a big difference in the drinking experience!
TWILLEY: But also, it must have really transformed beer and wine-making—the taste and look couldn’t hide behind the container anymore. Your wine and beer were naked!
GRABER: Enjoying beer and wine is definitely important. But some would argue that the even more important and transformational impact of this super clear glass was that it led to the invention of scientific lenses. Suddenly you could see things that were very tiny—cells—and also things that were very far away, like galaxies.
BEISER: So in a very real way, the invention of this transparent glass opened up, you know, powered the Scientific Revolution that has just opened up the world around us and the galaxy that surrounds us.
TWILLEY: So far, this has been a very Mediterranean story. And in fact, Vince says that Europe’s glass-making prowess—especially the lens thing—it really created a technological gap with the rest of the world. He says that places that were super advanced in other ways, like China, didn’t focus as much on glass and it meant they couldn’t see space or, you know, microbes. Drink.
GRABER: In Europe, though, in the centuries after the Venetians figured out how to make beautiful clear glass, glass became increasingly popular, and European glassmakers set up shop everywhere they could find good sand.
BEISER: Colonists in, in Jamestown, the original Jamestown settlement, started up a glassworks. There’s been big deposits of silica sand found in places like Wheeling, West Virginia, which so they started up a big glass making industry there. By the way, this is a lot of the forests that used to cover New England, Massachusetts and Pennsylvania. A lot of those forests were chopped down and burned to create heat to make glass.
TWILLEY: The process for making a glass bottle hadn’t really changed in centuries. American glassmakers did exactly the same thing that had been happening in Europe forever.
BEISER: You literally blow down the pipe, which inflates the glass, it takes a lot of lung strength to do it, but it inflates the glass. And you kind of keep turning the pipe to give it the shape that you want, or sometimes they’d put a cast iron mold around it. It’s a really finicky process. It’s a really dangerous process. You need help shaping it, you know, poking and prodding it to get it the right shape. And a lot of that work, a lot of the most dangerous, close into the glass work was done by children.
GRABER: Kids were small and nimble and frankly they were cheap to hire. The whole process was really labor intensive, and it took a long time to make a glass bottle.
BEISER: In the late 1800s, a standard crew would be five to eight men, men and boys, working 10 hour shifts. And they could produce about one bottle per minute. So pretty fast considering everything that that’s involved, but still you’re not going to make a whole lot of bottles.
GRABER: Bottles were super popular, but they were still kind of a luxury item. So like let’s say you were a brewer, you couldn’t just bottle your beer and sell it anywhere.
BEISER: You would sell it to local bars and taverns in barrels. And then if you are just, you know, Joe, you know, Joe factory worker who wanted to take some beer home, you’d have to take a jug or a bucket or something to your local brewery and then carry it home by yourself.
TWILLEY: Until Michael Owens came along.
BEISER: So Michael Owens is a almost entirely forgotten, but tremendously important historic figure, not only for America, but really for the entire world. He was the son of Irish-Scotch immigrants who came over and just wound up in West Virginia. And like a lot of boys, he went to work in the coal mines at about the age of six alongside his dad. But one day, he was working away in the coal mines and somebody whacked into a coal seam with a pick right next to him and a chunk of coal flew out, smashed him in the head, knocked him unconscious. So his mother thought, well, this is starting to seem a little bit dangerous. But we still need the kid to work. So they send him to work in a glass factory.
TWILLEY: And then one day another Michael comes to town. A man called Michael Libbey.
GRABER: Michael Libbey was a glassmaker from New England. And he had a few problems back at home. One, as Vince mentioned, the forests were disappearing because glassmakers were burning them.
BEISER: And secondly, because his workers, irritatingly enough, had the temerity to start unionizing and asking for higher wages.
TWILLEY: So annoying. Michael Libbey, like many an American before and since, looked West. Specifically to Toledo, in sunny Ohio.
GRABER: Turns out that Toledo has really high quality silica sand, so town leaders headed out to the east coast and invited glass makers to Ohio.
BEISER: So a bunch of those people came out and actually turned Toledo, Ohio into—for many decades, Toledo, Ohio was the world’s number one glass producing region.
GRABER: Michael Libbey set up shop in Toledo, but he needed some workers. So he headed to Wheeling, West Virginia to recruit, and he met Michael Owens. By this point, he was no longer a kid.
TWILLEY: Michael Owens, remember, had not had the benefit of a formal education. He’d never been to school. But he knew everything about the glass making process.
BEISER: So he comes up to, to work for Libbey in Toledo, Ohio in about the 1890s, right as the Industrial Revolution is really getting into gear. And Michael Owens looks around, sees how machines are taking over from human labor in all kinds of ways. And he figures, you know, what, I can figure out how to make a machine that’ll blow bottles for us. And he manages to talk, Mike Libbey, the owner, into backing him in this R & D effort. And the two of them wind up spending years and something like $500,000 on it, which was a lot of money back then. But eventually in 1903, they invent… Michael Owens, really primarily invents, the world’s first bottle blowing machine.
GRABER: There are illustrations of the machine on our website—it was wild looking, a tangle of metal tubes and rotating arms, it looks like a huge metal angular octopus. Or from another vantage point kind of like a carousel. Each of the rotating arms had a pipe on the end and then a mold.
BEISER: And it basically automates the whole process, right? An automatic arm comes out, sticks its blow pipe into the molten glass. Then a pump sucks in, sucks the glass up into the, into a mold then pushes it out to send a burst of air, blows glass into just the right shape.
TWILLEY: It is impossible to overstate how weird and complicated this thing looks—here’s a video that the company made so you can hear it at work.
CLIP: Vintage video of the Owens bottling factory
NARRATOR: Here’s one of the two basic types: An Owens vacuum machine, a spider-like monster with an insatiable appetite for molten glass. Listen to it.
NARRATOR: Spinning round and round, as its many arms dip in the revolving furnace pot, each drawing up a part of the fiery liquid.
GRABER: We’ve got the video on our website, gastropod.com. But the most important thing wasn’t how cool it looked, it was how much more efficient it was. Instead of eight to ten people making one bottle a minute, the machine could make a dozen bottles a minute.
BEISER: The machine sped up the process enormously and cut the cost from something like, where it cost about $1.80 to produce a gross, a dozen dozen of bottles, cuts that price down to 12 cents.
TWILLEY: And the two Michaels, Michael Owens and Michael Libbey, licensed this machine to other companies, and so soon everyone was cranking out millions and millions of bottles.
BEISER: Now there’s two things that are important about these bottles. One is: they’re cheap and there’s lots of them. Which is a huge boon. If you’re trying to sell anything that comes in bottles, right. Any kind of beverage, things like ketchup, mayonnaise, peanut butter, food stuffs. But also just as importantly, all the bottles are exactly the same size. Because they’re made by machines. And that means that you can also put them on an assembly line and have machines cap them and seal them and pack them into standardized crates.
GRABER: This was all happening in the early 1900s. And because of these new cheap, standardized glass bottles, small local food and drink companies could become big national companies.
BEISER: All of a sudden if you’re the Heinz company, and this is a true story. If you’re the Heinz company, you’re a local regional purveyor of tomato-based products, you can put your tomato based product in a cheap glass bottle, put it on a truck, which is another new invention that’s just coming to the fore and you can ship that ketchup all over the country. So almost overnight, you have, you, you have the ability to send your beer, your peanut butter, whatever it is you’re making, you can, you can package that stuff far more cheaply than ever, send it all over the country. So consumers, all of a sudden have access to all kinds of different foods and beverages that they did, that they never had before.
GRABER: Metal cans at the time were kind of heavy, they were also expensive, they were hard to open, and they affected the taste and color of the food. These new glass bottles were revolutionary.
TWILLEY: One of the big beneficiaries of Owen’s invention was Coca-Cola.
BEISER: Coca-Cola was introduced just before Owen’s bottle making machine was. It was doing pretty well. Within two years, sales had exploded into the hundreds of millions, and the Coca-Cola company itself credits the availability of cheap bottles as a big part of that.
GRABER: Toledo had already been a center of glassmaking, and this bottle making machine made it an even more important part of the growing American economy.
BEISER: The problem is, of course, if you’re making all those bottles, if you’re suddenly making millions and millions of bottles, those bottles are made out of glass, which is made out of sand. So all of a sudden you need a lot of sand, of this high purity silica sand. And they start digging it up from all over the place.
TWILLEY: Only ten years after Michael Owens’ machine was introduced, you start seeing newspaper articles complaining about sand sucker boats stealing the bottom of Lake Michigan to sell to glass makers. The entire shore of the lake was vanishing in front of people’s eyes.
GRABER: Including a popular tourist attraction, a 300-foot giant sand dune called the Hoosier Slide. A lot of the sand from the Hoosier Slide went to the Ball corporation—this is the company that still makes Mason jars today, the jars that are famous both for preserving food in and also for drinking beer in Brooklyn.
TWILLEY: And other hipster neighborhoods, let’s be fair.
BEISER: There was a pair of brothers named Ball who started up a glass making operation, in Ohio in the same region as Libbey. And they loved this Hoosier slide sand, because it gave the glass a special blue tint. Very pretty blue tint.
GRABER: Those blue-tinted mason jars are now collectors items because… every last grain of the Hoosier Slide was turned into glass.
TWILLEY: An entire 300 foot sand dune vanished in just a few years. And then the glass makers moved onto the rest of the Indiana dunes.
BEISER: And they were literally mined out of existence. All of the sand that makes them up was hauled away and melted down into glass until the 1970s, when finally conservationists stepped in and managed to preserve the very last few sand dunes. So it’s now a state park, the very last few sand dunes. All the rest of it? Gone. Turned into bottles.
GRABER: And the other thing that disappeared because of Michael Owens’ bottle-making machine? Child labor.
BEISER: Yes, it’s funny because so Michael Owens, one of the things that he is remembered for when he’s remembered at all, is he is really credited for helping to end child labor in America.
TWILLEY: Vince is laughing because actually Michael Owens was all in favor of child labor.
BEISER: He kept insisting, you know, right up until he was a very old man, he said, you know, it didn’t do me any harm. I think young men, you know, kids, it teaches them toughness, toughens them up and really, what’s the big deal.
GRABER: When he was a kid working with glass, about a quarter of the glass industry was made up of children.
BEISER: Along comes Michael Owens bottle making machine, all of a sudden it puts the livelihoods, it puts the jobs of practically everyone in the glass making industry in jeopardy.
TWILLEY: There were fewer jobs available for glass makers in general, and kids were obviously undercutting the adults because you could pay them less—so now glassmakers saw these kids as competition.
BEISER: So the glass makers’ unions all of a sudden became big advocates for the elimination of child labor. And sure enough, by 1919, fewer than 2% of all people working in the glass making industry were children. So it dropped from 25% to 2% just in a couple of decades and people really credited Michael Owens’s invention with that, quite rightly.
GRABER: So we have Michael Owens to thank for Heinz ketchup, Coca-Cola, vanishing sand dunes, and the abolition of child labor. Quite a legacy.
TWILLEY: I think it’s time to go back to Europe. Because while Michael Owens might have moved glass making forward in a commercial way, back in Europe, glass making was getting another scientific boost—a boost that would end up creating more evenly browned pie crusts for everyone!
GRABER: Remember those lenses that were so critical to the scientific revolution, the ones that were made possible by the Venetian invention of truly clear glass? The lenses were amazing, but they weren’t yet perfect. The glass was a little streaky sometimes, and sometimes the colors in the glass separated out into blue and red as if you were looking through 3-D glasses.
RAMIREZ: So in Germany, there was a gentleman named Otto Schott. He developed a new type of glass. What he did is he added a little bit of boron to it. And what it did is it improved those optical properties so that it no longer had the separation of the blue and the red as it had in the past.
TWILLEY: Ainissa has a whole chapter in her book about this glass with boron added to it. It’s called borosilicate glass. And Zoe says it’s not just better for looking at stuff through.
LAUGHLIN: So the boron really is the thing that stabilizes the glass and makes it heat resistant.
GRABER: In normal glass, the kind you might be drinking out of, it expands when it’s hot and contracts when it’s cold, and that’s why you don’t put a drinking glass on the stovetop or take it out of the freezer and pour super hot boiling water into it.
TWILLEY: Because if it expands or contracts too much, too quickly, it shatters. This is called thermal shock.
LAUGHLIN: When you add boron to that mixture, the boron spreads itself out kind of into the structure of the glass and stabilizes it and prevents such extreme amounts of expansion and contraction. It doesn’t mean there isn’t some, but there’s just much, much less. So it makes much less movement. And then that creates—well, it enables it to withstand what we describe as thermal shock. Basically it means that a borosilicate glass can withstand much, much higher temperatures than your regular soda lime glass. You can suddenly make glass beakers for chemistry, that you stand on top of Bunsen burners and boil up liquids and look at how chemicals change during the application of heat.
GRABER: Schott discovered one other thing—not only was this borosilicate glass clearer and more heat resistant, it was also much stronger and much less likely to break, and so borosilicate glass became super important to the advancement of science.
RAMIREZ: And so he then designed a whole range of different glasses and created a huge business. And people loved this German glass. They wanted Schott glass. And so, that was a monopoly that Germany had in terms of scientific glassware.
TWILLEY: Schott moved to a town called Jena, in Germany, so sometimes people called this borosilicate glass Jena glass, He went into partnership with a man called Carl Zeiss—and you still find Zeiss lenses today, on cameras and telescopes. Together they made the best lenses, and the best test tubes…
GRABER: America had some great glassmakers, like Corning Glass—but they didn’t know how to make this awesome borosilicate glass that all the scientists wanted.
RAMIREZ: And then when the German glass became very popular, they’re like, well, look, we need to try and find an equivalent to that. So then they started hiring chemists and physicists to try and figure out what Otto Schott had done.
GRABER: Corning Glassworks of Corning, New York—actually, to go back to my mom here, she took my brother and me there on a family vacation when I was in high school, of course she did—
RAMIREZ: Corning was in the business of selling glass and they first made the shields for light bulbs for Edison. And that was a good business and that was a steady business, but they wanted to increase their business.
TWILLEY: So the scientists at Corning read Otto Schott’s papers and they played around a little in the lab and through trial and error they made their own borosilicate glass. They called it Nonex for non-expanding glass.
GRABER: Nonex worked—you could use it in scientific experiments, just like the German glass, but the German glass already had the market cornered. People were familiar with it, and it was pretty cheap. So Corning decided to get into the booming railroad business, in particular the lanterns along the tracks.
RAMIREZ: The railroad used these lanterns to tell trains whether they could go or not. And if a red signal was there, the train would move. And if it wasn’t there, well, they knew that they could proceed.
TWILLEY: That system worked perfectly on nice days. On cold, rainy, or snowy days, not so much. The arc light inside the lantern was super hot, and so the glass shield would get hot on the inside and expand. But it was cold on the outside, and that would make the glass shrink.
GRABER: And like we just explained, the dramatic difference in temperature and the expanding and shrinking at the same time made the lanterns shatter any time it was cold outside. And that meant conductors couldn’t see the red light and they’d keep going and maybe crash. This was a perfect market for this new Nonex glass, and soon the nonshattering Nonex was on all those lanterns, making everyone a lot safer.
TWILLEY: But as soon as it was on all the lanterns, sales really dried up. Because the new Nonex glass didn’t break so it didn’t need to be replaced. Crap.
GRABER: And then someone new showed up at Corning in 1913, his name was Jesse Talbot Littleton, he went by JT.
RAMIREZ: JT was a glass man. He was pretty dedicated with this. But when JT would come home for dinner, his wife would make Jell-o. He would break the Jell-o apart. And he would talk to his kids and say, okay, well, this is how glass breaks. And he also told his children later on in life that he wanted to be buried in a glass coffin. He was very dedicated to, to glass.
TWILLEY: JT had just finished his PhD dissertation at the University of Wisconsin. Surprise surprise, it was on glass. Specifically, it was on the heating properties of glass. And his findings really were a surprise to his Corning colleagues. They had all assumed that heat would not spread through glass the way it did through metal. JT knew otherwise.
GRABER: The other important person in this story is JT’s wife Bessie Littleton, she loved to bake. But her favorite pottery casserole dish had shattered. At a dinner party, she heard all the men bragging about how unbreakable their Nonex glassware was. So she said, well, why don’t you make me some indestructible cookware?
TWILLEY: The Corning scientists didn’t think Nonex would work as a baking dish.
RAMIREZ: They didn’t think that cooking with glass was a good idea because their thinking was that glass wouldn’t cook very well because it has a very thick wall.
TWILLEY: But JT decided to listen to his wife, which is always a good idea.
RAMIREZ: Back then they had these things, they were called battery jars. And he got one of those, those battery jars that was quite wide, about 12 inches in diameter. And then he cut it so that it was about three inches high and that’s what he snuck home to share with his wife Bessie. And she cleaned it up and then she poured some batter in and baked a cake inside of it.
GRABER: JT brought that cake to work the next morning.
RAMIREZ: And people said, okay, it’s nice to have cake. It’s kind of early, it’s in the morning, but okay. We’ll have cake. And then he said, Oh, by the way, this cake was made with glass. Now you can imagine the scene where everyone is sitting there and then the food falls out of their mouth. And they were like, no way, you made this with glass? And so when he said, you know, I cooked, this was cooked in an oven. They were just like, All right, you got to prove it to me. So they actually had him go back and tell Bessie to make another cake. Let’s make sure that this is not a one-off, let’s make sure this is actually how this cake pan actually operates.
GRABER: So she made another cake. And just like the first cake, it was a gorgeous even brown color, even better than the cakes she baked in her metal or pottery pans, and it came out of the pan more easily, too.
TWILLEY: Bessie kept going. She made steak and cornbread and French fries and collard greens in her new Nonex glass pan. The food didn’t stick, everything cooked perfectly, and the glass pan didn’t hold onto any flavors the way her cast iron skillet sometimes did.
GRABER: The Corning scientists wanted to figure out why the glass was so perfect, particularly for the browning of the food, why it cooked everything so evenly and beautifully.
RAMIREZ: So the first thing they did is they got two glass pieces and they dip one into plating solutions so that it had a mirror finish on the outside. Then they put cake batter in both and put them in the oven and had them bake. They found that the one without the mirror finish baked okay. But the one with the mirror finish did not. This informed them that the cake was being cooked was by those invisible rays inside of the oven.
GRABER: Food cooks in metal pans because the food and the pan heat up from the air in the oven, that’s called convection, and the pan also heats up from touching the rack beneath them, that’s called conduction. But glass pans also work through the third form of heat transfer—radiation. These are invisible waves of energy that transmit heat. Glass pans let that radiant heat through, and metal pans block it. So glass is actually better in the oven than metal is.
TWILLEY: Time to come up with an exciting name and start selling these glass pans!
RAMIREZ: Well, they wanted to make sure that the customers, particularly women, knew what the product was all about. So they called it PIE-rite.
TWILLEY: Like a pie, but spelled PY to seem cooler and more futuristic.
GRABER: But Pyrite didn’t quite hit the mark. They thought about their other product, Nonex, and Latex, and how sciency those sounded…
RAMIREZ: So instead of Pyrite, why don’t we call it Py-rex?
GRABER: Pyrite was renamed Pyrex in 1915. For a couple of years sales were kind of slow.
RAMIREZ: They had to learn a couple of things. They would give the product out, have people test it. They actually had what they call domestic scientists, people cook in it. They had to show women how to cook in it because people had been cooking in metal pans and they see glass. And so they had to, they had to be educated that this is another way that they could cook. Also they had to make some modifications. Sometimes the handle was too thick. Sometimes they made the object too heavy, so they had to make some modifications that way. And then they also learned that people like colors and people want to have pans for specific things. Well, I want something for a pie and I want something for bread and I want something for cupcakes or what have you. And then it took off. Millions were sold every year.
GRABER: Since then, bakers have discovered even more benefits to cooking with Pyrex. You can see your pie crust through the glass to check how well it’s browning. Acidic dishes like a lemon sponge pudding, a kind of British cake, the lemon could react with the metal pan and get a kind of metallic flavor, doesn’t happen with Pyrex.
TWILLEY: This is confusing to me. I actually own a Pyrex dish, but I don’t reach for it when I’m baking. It’s 2020, this magical Pyrex stuff has been around for a hundred years, so why do I still use metal tins to make cakes?
RAMIREZ: Well, I don’t know why you’re doing that. I’m just teasing. Well, I mean, Pyrex is a specialty item. It’s a little expensive. You know, metal pans are easy to get, Pyrex is actually passed on from one generation to the next. So, you know, it’s just a matter of, it’s something that you were accustomed to, or if someone had it in your household. But metal pans are perfectly fine for making cakes and metal pans actually have other features. If you’re making a cake and you want to remove it easily. My brother is a chef. He has a special metal pan where the sides, you can flip a clip and this thing opens up. And so the sides will come off and you don’t have to worry about scraping the side and you can make a beautiful cake. You can’t do that with Pyrex. So Pyrex is a, is just a preference that some people have. It doesn’t, it’s not necessarily better than the other. Some people like it for some things and some people don’t.
TWILLEY: Now I want to try baking a cake in my Pyrex dish.
GRABER: So here’s a question, though, do you have European Pyrex or American Pyrex?
TWILLEY: Well, when I bought it was European. Now it’s British. Curses.
GRABER: Okay, but it’s still better than American Pyrex—which unfortunately is no longer borosilicate glass, it’s now tempered soda lime glass, which is like your drinking glasses but made to be much harder and also heat resistant. BUT it’s not quite as shatterproof as borosilicate glass. So Americans can cook in Pyrex, but there’s a lot of fine print from the company about how to use it. It can actually shatter.
TWILLEY: Materials scientists say that the new American soda-lime Pyrex can withstand about a hundred degrees of rapid temperature change, whereas the borosilicate kind is good for more than three hundred degrees. So actually, we’re back to where we started where the Europeans have the lock on shatterproof glass. Plus ça change.
GRABER: Most of the glass in our kitchen is this cheaper, more breakable variety.
LAUGHLIN: Well, the glass that we sort of know and love today is a sodium lime glass. So sodium carbonate, calcium carbonate and sand. And those reduce the melting point and they help with the transparency. And it makes for the sort of pretty, cheap and easy to make object because of that lower melting point. So the majority of vessels are made out of it and it’s pretty easy to break, but also pretty easy to mold and shape when it’s liquid. So you get a huge variety of forms. But the glass stuff doesn’t really change from a wine glass to a water glass to a jam jar glass. Like that’s all sodium lime glass.
TWILLEY: It may all just be glass, but like Zoe says, you really do get a huge variety of forms. In my cabinet I have some champagne flutes, and wine glasses, and pint glasses, and some whiskey tumblers and even a couple of glasses that are just for one particular type of beer.
GRABER: I have to admit that I love the shape of different glasses from an aesthetic point of view, but I have always been a little skeptical about whether or not all these different glasses make a difference in terms of how something actually tastes. Is there any science to putting, say, burgundy wine in that huge bowl shaped wine glass?
LAUGHLIN: I mean, I’m not aware of any really formal, rigorous studies, but there’s definitely a perceptual effect and there’s definitely an experiential difference. That’s for sure. Which means therefore there is a difference.
TWILLEY: So… sort of? We’ve actually tracked down some of the studies that do exist on the topic how glass shape and flavor interact, and we’ll be sharing that research in our special supporters newsletter. Which you can receive! As long as you support us by giving at least $5 an episode on Patreon or $9 a month on our website Gastropod dot com slash support.
GRABER: Whatever the shape, we all still drink wine and beer from glasses today, just like people loved to do hundreds of years ago.
TWILLEY: But these days, glass has a lot of competition.
BEISER: Yes, we still use a lot of glass for packaging beverages, especially especially alcoholic beverages. It’s still a multibillion dollar industry, but beverages across the board, plastic bottles and metal cans now make up about 80% of the beverage packaging market.
TWILLEY: Glass is great, better than plastic or metal in lots of ways. But not in one really important way. Glass just weighs a lot, and that matters when you’re shipping stuff all over.
GRABER: But even though glass isn’t what most food is packaged in today, there are still glass innovations to be made. For one, Zoe’s working on even tougher glass.
LAUGHLIN: I’ve had a go at trying to make an unbreakable glass for an airline where you’re trying to think, where you want the experience of glass, you want the cold, hard, very smooth, delicate object that makes drinking liquid from it, that bit more refined than, like a paper cup or something or plastic beaker.
TWILLEY: Airlines are serving expensive wines to their customers in first class and business, and those just don’t taste the same in plastic, so they use glass—but then it breaks all the time.
LAUGHLIN: So we just had a go at making an unbreakable wine glass. And it’s—it is possible to make something that is very, very difficult to break. But it doesn’t necessarily lend itself to the most elegant object. You know, so there is a tradeoff in shape that you have to enable if you want it to be very robust.
GRABER: Zoe said she had to go back to the drawing board to solve this problem.
LAUGHLIN: Changing the shape. Tweaking the material. Going back to borosilicate glass. So the kind of ultra strong Pyrex type things, but then trying to hone and refine so it doesn’t have to be this chubby, lumpy slightly—well, actually, I mean, when we made a thick one, it was rather lovely and it was pretty charming. But you want that thinner rim. So it’s about how thin can you taper it to the mouth area so that it feels—when it goes into your mouth that it cuts the liquid nicely.
LAUGHLIN: It worked—it worked pretty well. I mean, I probably can’t say much more than that with the NDA. But it did work pretty well.
TWILLEY: So given how much glass we use these days—I mean, it’s not just my kitchen cabinet, it’s the entire Internet—are we going to run out of sand? I can’t help thinking about the vanished Hoosier Slide and worrying that one day there will be no beaches.
GRABER: Vince’s book is all about sand, and he spends quite a bit of time in the book on this very question. Sand is running out—there are sand pirates stealing sand from beaches, yes, but it’s a different kind of sand.
BEISER: We use about 10 times more sand for concrete than we do for all glass put together. Eventually of course we will run out if we keep consuming it the way that we are, but there doesn’t seem to be the same pressure on glass sand resources that there is on, on concrete sand. So you don’t have organized crime getting into the silica sand business, you don’t have massive environmental damage being done to get at silica sand, the way that you do for concrete sand.
TWILLEY: OK, so that’s a different problem to worry about another day. But the fact that there isn’t a glass sand shortage does make me feel better about all the glasses that Zoe has sacrificed in her quest to shatter a glass by playing a musical note.
GRABER: So you can just shatter glass by playing a really loud sound—any really loud sound.
TWILLEY: But the trick behind shattering a glass by singing is pretty simple. You just have to find the right frequency.
LAUGHLIN: It’s basically hitting the same note the glass makes if you were to flick it with your finger, it will go “ping.” Well, you just got to hit that same “ping,” that note, fire that note back at it. If you hit another glass, it might go “paaang.” Like, you just got to hit the sound, whatever sound that glass makes, you got to play it back at it.
RECORDED SOUND OF HITTING GLASS
GRABER: When you sing or play the note that the glass makes, you’re vibrating the air around the glass at that frequency, and it then makes the glass vibrate at that frequency, too. And the louder the sound, the more energy, the more the molecules vibrate. With enough energy, the molecules will vibrate so much that they’ll shatter.
LAUGHLIN: But the tricky bit wasn’t so much the energy as tuning into the frequency really. Because its own resonant frequency was so specific.
GRABER: Zoe figured out the right frequency for the right glass, and the right loudness to play, and she put on headphones. And she filmed herself aiming a soundgun right at that glass.
TWILLEY: One twentieth of a second of sound was enough to do the job. But when Zoe watched her footage in slow motion, she noticed something amazing.
LAUGHLIN: It cracked in a repeatable way, which was from the stem all the way up the bowl. This vertical line shot up and half the glass sort of split away. And then the other half had sort of crumble and split away. And over and over again, these wine glasses would break in, in this way.
TWILLEY: All the glasses broke the same way—at the weakest point, where the stem joined the bowl—but they all shattered at different frequencies. Which made us wonder: could you write a piece of music that would shatter an entire bar’s worth of glasses, by hitting all the right frequencies?
LAUGHLIN: So on paper, you could definitely write music that had all those frequencies in it, but it would it wouldn’t just go around breaking glass left, right and center. Because yeah, because of the practicalities of how you have to actually do it. But I’ve always wanted to make a piece of music or like, do a collaboration with an orchestra where I made a series of glass cymbals and you’d score into the music, the smashing of the cymbal in the way that was actually to break the cymbals.
TWILLEY: Do we have any composers in the audience? Maybe this is Gastropod’s first opera? I mean, everyone knows my musical talents. You heard me sing Vindaloo in our curry episode!
GRABER: I sang along to the theme to iZombie in our cannibalism episode, I thought I did a pretty decent job.
TWILLEY: Well now it’s a competition. Who can shatter the most glasses?
GRABER: Hey, if that’s what it takes to get us on stage again for a live event, some day in the future, I’ll drink to that!
GRABER: Thanks this episode to Zoe Laughlin, materials scientist extraordinaire of the Institute of Making, and to Vince Beiser, author of the fascinating The World in a Grain: The Story of Sand and How it Transformed Civilization. And to Ainissa Ramirez, who has a great new book out called The Alchemy of Us: How Humans and Matter Transformed One Another. Links on our website, gastropod.com.
TWILLEY: Thanks also to Gastropod’s summer fellow extraordinaire, Sonja Swanson, who helped produce this episode.
GRABER: We will be back in two weeks with, wait for it, lobster sex!
TWILLEY: Trust us, it is hot! Really surprisingly kinky.