MOLTEN GLASS VS Prince Rupert's Drop - Smarter Every Day 285

Do you know what this is? If you do, you're going to be, like, super excited about this video. If you don't know what this is, let me bring you up to speed. This is called a Prince Rupert's Drop, and it's created by dripping molten glass down into water. Now, when that happens, this really interesting material science thing happens, where the outside is an extremely high compressive stress. But the inside of this drop is in extremely high tensile stress. What that means is you can hit the tip here with a hammer and it won't break. It's glass, but it doesn't break. You can even hit it with a bullet. And I've done that here on this channel, and it shatters the bullet. But if you even nick the tail, it explodes. I get really excited when I do this. It explodes. Watch this. I now have a mess I have to clean up. So, a prince. Oh, wow. It's everywhere. That little moment where it explodes, I wanted to capture that. And so what I did is I cast a Prince Rupert's drop in epoxy resin, and then I shattered it, and I tried to capture the exact millisecond of the explosion.

Now, a lot of people watch this video and they're like, "Oh, well, you did it wrong. You didn't use the right epoxy, you didn't vacuum off the gases correctly." And these are fair questions. I mean, look, it's yellowing. It's not as great as I wanted it to be. But there was one person that saw this and asked a very different question, and that was Cal Breed, the man who made the original Prince Rupert's drop that I showed here on Smarter Every Day. Cal's question was, "Should you be using epoxy at all? Couldn't you do it with glass?" To which I replied, "What? What? Think about it. A Prince Rupert's drop is glass. Putting glass inside molten glass has to change things, right?" It's a very difficult problem.

So today on Smarter Every Day, we're going to get into the mind of an artist who understands the material properties of glass far more than any engineer I know. And we're going to see if we can put a Prince Rupert's drop in molten glass and shatter it. Let's go get smarter every day. This is Cal. He's the owner here at Orbix Hot Glass. What we're going to do today is we're going to have fun. And I have fun by making weird stuff. And I've got a great team of awesome people that like making weird stuff with me. We've made clear Prince Rupert drops; I want the ice blue one, and so we're going to pick up some ice blue glass. We buy colored glasses, and then we can break off a chunk of it, put it in here, heat it up to a thousand degrees. This is, we park it in the garage. So this is our garage. It's hot enough to keep the glass from cracking, but it's not hot enough that it's going to slump.

We're going to pick that up on the end of a rod here in a minute. Heat it up, pre-heat it a little bit more up in that top corner. What do you mean, "Up in there?" Yeah, up in the top left corner there, that's going to be the hotter area. Yeah. And then we'll bring it out and put it into here, which is closer to 2000 degrees. This is what we use when we're making anything throughout the process, just reheating. You can't just make it in one gather and it's done. We're going to heat up that blue, make it into little pieces, so that we have multiple tries because the colored glass for some reason doesn't want to be made into Prince Rupert drops. The clear ones we can do in a small bucket. They can hit the bottom and they're fine. But with the colored ones, if they hit the bottom, they typically break.

Jill, for some reason, has a knack. We figured out that she has a higher percentage right now. Do you have the magic touch for the color drops? -I guess so, yes. What's the secret? What? I'm not. I'm not sure. She's just lucky. -You just know what's up. I'm just able to do it somehow. Yeah, I have a higher percentage rate of success. That's, that's awesome. Okay, you see what's happening here? We are already learning that these artists have a feel for glass in a way that an engineer doesn't. Like, they understand it in a more intimate way. You heard Jill there, who's an apprentice under Cal, talking about how she's able to do certain things and she can't really articulate it. She just feels it. She knows what she's doing.

So when I think of this, this is just clear glass. When I see this, this is colored glass. They didn't make this, by the way. They make way prettier stuff. So I just see clear glass, colored glass. But these artists see temperatures and gooieness at certain temperatures. And they have an intimate level understanding of how this stuff works, which is fascinating. So today we are going to be working with Jill, who you met there. We've got Eric, Lily, and Bodi. These are people who are all working under Cal, which means they're learning just like Cal did. Cal has apprenticed all over the country under some of the huge names in the glassblowing world. It's cool to see how this knowledge is passed down through exploration. And Cal explains here what he and his wife Kristi were thinking when they started the studio.

"When we built the shop, we wanted to make sure it was like a mad scientist kind of place. So you come up with ideas, and let's try to make it," similar to what we're doing today. It's a process of learning how to explore, how to learn, and then you have your ideas, and you come in here and try it. Alright. We now know that glass behaves differently depending on what color it is. So I asked Cal to explain some of these colors. "Yeah. So this is like an ice blue. You can see how beautiful that blue is. These are very dense bars of colored glass. So if you were to use emerald, it's so dense, it almost looks black." Right. -Okay. Which is why I chose this ice blue. I love this color anyhow, but it's more transparent.

A little later, I explored these colors more with Eric, who explained that the physical properties and the color itself are not only a function of the chemicals inside the glass, but how you heat it and cool it. "Copper Ruby, this is a very interesting color. This will go completely clear when you're working on it. Completely. And then once you put it in the oven, it will turn blood red. And if you get it too hot, sometimes it'll just go clear. It's a very bizarre color." "I've never heard some of these words. -Aubergine. It's like a purple. Uranium is, oh, no way." -Out of? Is it actual uranium? -Yeah. Yeah.

Okay. So to make the individual Prince Rupert's drops, they need to break up that one piece of blue glass they had been warming up in the garage. And to do that, they attach a thin, solid metal rod using already molten glass as glue on the tip. That grabs the blue piece. And then they put that in the glory hole, they heat it up even further, making it malleable. Then they form individual balls that they can break off in a really interesting way. "So you just broke that off with a mechanical vibration. Every time we're making a piece, we have to eventually get it off the blowpipe or off the punty rod. So we're going to create a weakness, you know, that we can shock, typically with temperature. And so putting a little bit of water on it or a cold tool in that weakness." -So and then tapping it, break it off. -So he's making the weakness now.

He's, yeah, well, he's kind of creating a narrow spot to make a good weakness. Yeah. -A stress concentration. So engineers and scientists, they think about materials a certain way, right? They've got aluminum and steel. And if you pull and push these things, they have certain things called a stress-strain diagram. Steel, you're going to pull it and it'll eventually yield and then break. Aluminum does the same thing, but it does it a little bit differently. Glass is different. It doesn't yield and stretch over time. It breaks because it's brittle. Glass artists are always thinking about that point right there, the point at which glass breaks. Sometimes they're trying to avoid that, like in the middle of a big piece. And sometimes they're trying to create that.

There's more to this, though, because they're going from liquid glass to solid glass. You've seen a graph like this before, right? This is the phase diagram for water. We can boil water from liquid and turn it into a gas. We can freeze water and turn it into ice. Right? We can move into the solid part of the graph. This is the way I always understood matter to work. You can just move around on this graph, change from solid, liquid, gas based on the pressures and temperatures. Well, yeah, that's true for water, but that's not true for all materials. Water has what's called a first order transition. Let's make a graph of viscosity versus temperature. If you have solid ice and you heat it up to turn it into liquid water, that phase transition happens very quickly in an extremely small temperature band. This is why water is called a first order transition.

Glass, however, is a second order transition, which means the phase change happens gradually over a wide temperature band. And you would think the graph of that would look like this: linear, but it doesn't. It works like this: cold, solid glass exists up here in the glassy region. But as you heat it up, the glass transition begins and you fall off, and the viscosity starts to change drastically, then suddenly it levels off in a rubbery state. This is known as the rubbery plateau. More heat is added and you drop off the rubbery plateau, and it starts to flow in what's called the rubbery flow region. If you add yet more heat, the glass will start to flow like a liquid. Look at this curve. Glass artists know how to use this curve to make glass do exactly what they want. If you were a glass artist, where would you want to work the glass? For me, it would be on the rubbery plateau. It's a relatively large temperature range that gives me the same physical properties.

That's pretty cool, right? So as a glass artist takes their work out of the furnace, it's a certain temperature, right? And then it starts to cool off. And so they have a certain amount of time to work it until it gets all the way back over to the glass transition region. And then they can't work it anymore, and they have to stick it back in the furnace and they move it back down the rubbery plateau, and then they come back and forth and that's what they're doing. They're controlling the viscosity by managing the temperature of the glass. They don't need to know these graphs to know what they're doing. They know it in their soul. Like engineers, we're thinking about the stress-strain curves and we're like, "Oh, the glass is going to break here."

Well, the glass artist is managing all this with the temperature of the material itself. So they're riding up and down the curves at all times, and they're just doing it. So what I want you to think about is this curve, because this is how I have to understand it. The first step for the team is to make the Prince Rupert's drops. Did it work? Oh, wow. -That's a beauty. Oh, that is so beautiful. -Yup. So now we have this beautiful Prince Rupert's drop. How do we get this thing in molten glass? The obvious answer is we need it to be transparent. Whatever we're going to hold the glass in. So it needs to be a glass. And so Cal has explained to me that he can't just go get a glass off the shelf and pour molten glass into it because the temperature difference will cause it to explode due to thermal stresses.

So what Cal has elected to do is create this glass as he's getting everything else ready. So it's going to be hot, and the temperatures are similar, and it's going to work out beautifully. And just the process of how he makes this is amazing. So what we're about to do, you can't do unless you have multiple artists doing different parts of the process. Is that true? Yeah. You have to have a team for this. There's no way you could do this by yourself. Everyone really has a great understanding of the material already, so this is only helping us learn the material better. I think we should just try it. -Okay. Sounds good. So the first step of making a drinking glass is to gather glass in the liquid flow region onto a blowpipe.

Cal then takes it out of the furnace, gets the blowpipe cool where he can hold it. And then he does this. What?! Did you see that? Back that up. Cal puts a little bit of air inside the glass and then he plugs up the end of the pipe with his finger, and then the heat from the glass makes the gases expand, and it does all the work for him. He used the ideal gas law to blow up the glass. That's amazing. -Just going to gather one more time over it. Blow, please. Good. Stop. So at this point, they have a sphere of glass, and now they're going to straighten the edges and make it a cylinder, and they're going to flatten the end. Watch how they do this. And you're thinking about temperature and thickness and things like that right now. -All of it. Yeah. Stop.

Okay, Eric, feel heat from here down, and we'll drop it out a little bit. So he's only going to heat it shallow. That way we can, ah, stretch it from the shoulder. We made a kind of a wide shoulder. We're going to stretch it down now. So once again, the heat differential plays part of how you shape it. Okay, so see how we had this colder shoulder? I was able to brace the tips of these off of and had her blow it up, and it blew the glass here. You made it a cylinder. -Yeah. So now he's going to heat it even shallower. So he's making it upside down, right? And so this part's cold, and this part's hot. So this part is already solid. So he can take his tongs and he can put them on down there, and he can push down and form the part that's hotter.

So they're in different parts of the flow regime on that curve, which is amazing. Also, he's rotating the thing because this part that's over here that's more droopy wants to droop down. This is incredible. So he's going to heat only the base now, so we can flatten and tighten that up. -Okay. After that more shallow heating, the end of it is more pliable so they can flatten it out. They do a combination of paddling and using the gases inside to make it fill out. After that, they then put another rod on the other side and they break off the cup, turn it around, and then they make the cylinder from the inside out. All the while, while we're doing this, Lily's over there putting some molten glass on a piece of kiln shelf.

So when we set the glass down, the kiln shelf won't be too cold and thermally shock the glass and break it. Can I briefly look at it? -Yes. Oh yeah. Yeah, that's awesome. Okay, now that the cup is finished, Cal started letting everybody know where they need to be when because he has to manage the temperatures and the timing. He has a big ladle that he's going to get molten glass in, and it's very dangerous. I got out of the way and went and got the high-speed camera ready, and I just sat back to watch. Okay, I think we're ready. Are you all ready? Yeah. -Ready. Oh, dude. I'll tell you when, Jill. I'll tell you when. -Holy moly. Now. Yeah, yeah, yeah, ya'll. We got to be a little faster on that big time. I want. I want to be able to lay that down and be able to pick this up and you be and shove it in there and boom.

I was still making my way back over. I mean, the glass is still, like, super gooey. Like, you could still put it in there, you know? Other than that, look, look, you did the cut perfect. Look, it's like flat in there. Looks like a cup of water, you know? -Yeah, yeah. So let's look at the slo-mo and see what happened. You can see when he triggered the tail of the Prince Rupert's drop, it ran straight to the molten glass and then did not go any further. Let's ask Jill what happened. What is it that you need to do quicker? I didn't quite catch it. So the snapping of the tail has to be done faster because the tail is so skinny. Once Eric shoved the Rupert's drop into the molten glass, they heated up so quickly that it like slumped over. So Cal has to snap it before that tail heats up.

Alright. It's getting complicated. Hang with me here. If you think about where the Prince Rupert's drop is on our curve, it's way up here. It's solid, right? It's cold, but it's not a lot of mass there. If you think about the molten glass, there's a whole lot of it, and it's really hot. So if you think about when the heat transfer starts, that molten glass is going to influence the Prince Rupert's drop a whole lot more than it's going to influence the molten glass, which means the Prince Rupert's drop is going to run down that curve down into the rubbery plateau. It's going to melt quickly, right? So there's a time thing we have to think about here. It has to do with heat capacity and the amount of time it takes one thing to heat up versus the other.

And the colors that we're doing, blues and greens are on the softer side of colors. So those tend to heat even quicker than, say, like a red or something like that. So, having learned the lesson, Cal and his team made another cup and got ready for another go. And now. Whoa, so you use cold water to do it. -Yeah, okay, things are happening and Bodi, you get your shot. Take your time. Take your time. That's still dripping, please. There you go, Jill. Okay, that was pretty. Look at that bubble coming up. Where'd the bubble come from? -I guess we must have trapped an air bubble. It'll probably come to the top. We can pop it with a torch. That should semi disappear. Nice. -Mhmm, cool. Are you happy with that? -Yeah.

Yeah, you know, I'd be great if I was, like, a master caster and I would not trap air around. For some reason we didn't catch all those on other ones. Well those are like when the glass is, like, folding in there like that. It's like, it's trapping air. This time the fracture ran down into the glass and we could see it on high speed. We tried it again with the deep blue one, and just like Jill was talking about, blue being softer, it didn't work. It didn't rupture and go down into the molten glass. So we had a failure on our hands. And at that point, Cal did something interesting. He had always talked about wanting a square one, so he put it on a punty and put it back in the glory hole.

There we go. Focus more on the back because it's colder there. Oh, you're making your square. Yeah. -You're making your square. I never thought about doing it this way. This would be a little bit less grinding. Okay. And it really got weird, didn't it? That looks awesome. Yeah. Typically, if I screw up, I want to screw up as many ways as I can in one go. Hmm, We'll see. I think it can be done substantially better. But this is a start. So you learn on the mess ups too, don't you? Yeah, that's what I was saying. Like, if we're going to mess up, let's mess up as much as possible so we can figure out as much as possible.

So is that why you started squishing it? Yeah. Like this is the one to squish. Let's go. Got it. So we did it one more time, and it's cool to see how the teamwork got better. The choreography of all the elements got smoother and tighter. And so much more calm. Okay. I'm ready, Eric. Push it in there, good. Good. Yeah. That was awesome. Okay. Cal, what's happening? I don't know, that one blew all over my face. Blew in my face too -Keep watching it because it'll heal up. The last one they did, it looks like a little cloud, and the cloud goes away. Really? Do you think that's glass flowing in there? What do you think is happening? No, I think just the heat is healing it, you know. It's just slowly closing up, isn't it?

Yeah. I don't think it'll heal any further. I think the rest of it is just a veil of air bubbles, you know? Let's watch that again at 41,000 frames per second. I love the lighting on it too. Whoa, that's awesome. That's fun. So you remember that Cal wanted to make a square one? Well, Cal told me that sometimes glass artists will use graphite to make molds, so I bought some modular pieces of graphite and started trying to put it together and then took it to Cal, who adapted it to his needs and figured out a really clever way of using it so he didn't have to make a glass cup every time.

"Yeah, cut it, please. We need to practice the cutting." Not quite molten enough. No. I'm still going to pop it. Ya'll watch your eyes. Oh, we didn't close the mold. Cut it. Remember, the shears move. Hold on, one second, one second. See if we can maybe get in whatever. Okay. Yup, push it in there. And that looked good. Yeah, it definitely worked in there. Okay, dude, totally going to admit. I did not think you could do that. Dude, that looks amazing.

So when we pulled these out of the molds, you could see that the inside is still very, very hot and the outside is cold. This ends up creating stress inside the glass. And glass artists have a way of dealing with this. It's called an annealer. Basically, it's an oven that gradually heats up and cools down the glass to relieve the internal stresses in the pieces. Now that the mold was working, the team could work even faster, and they can figure out what worked and what didn't. Okay, that looks. Yeah, I think we got something -Absolutely awesome. Yeah, I think we got it. Yeah. -You like it? Yeah, yeah, yeah, yeah, yeah. It was good that time. That one before that is still pretty rad. That looks so cool. That looks awesome. Sweet. I love it.

Yeah. It's good. I think. I think you got it. Yeah. Boom. Nice. Yeah. Yeah. Good teamwork right? There ended up being a ton of failures, but a select few were chosen by Cal after they came out of the annealer to be worked in the cold shop. The cold shop is where Cal uses an assortment of tools to cut, grind, and polish his art pieces to their final form. The cold shop is all about patience. He uses a variety of grit and diamond tools like this lapidary wheel to make flat surfaces. He uses an interesting wobbling tool called a reciprolap to passively polish surfaces using silicon carbide grit. He also uses this diamond wheel to fine tune surfaces and shape them to exactly how he wants.

Glass is an amazing material. There are trade-offs for how you make a piece. When something is blown, the surface finish is perfect immediately, but when it's cast, sometimes you see what Cal calls the elephant skin on the outside, which Cal often spends hours and hours smoothing. A quick flick of the wrist or nip with a tool in the hot shop can easily translate to dozens of hours of work in the cold shop, where Cal carefully refines every surface of the art piece until it catches the light just right, revealing the final piece as he imagined it.

Eleven years ago, I wrote an email to a guy named Cal Breed. I was an engineer and he's an artist. And the engineer needed a little thing called a Prince Rupert's drop. I think it's fitting that my deepest understanding of this topic came when I went back to the guy that created it and tried to get into the mind of the creator and see what he did and how he was thinking. And once I did that, I started to understand this material at a much deeper level than I initially even hoped to understand things. And so now I would like to show you the piece of art that Cal made out of this. I think it's beautiful. It's like the bottom is folded on there.

I think it's pretty, man. I mean, I think you're able to see really like the folds of the glass and then those skins piled upon each other as it was pushed in. But the fact that it shattered, it shattered, but it's, you know, it doesn't have much room to go. The glass has got such a thickness to it. Right? It's like this weird moment of fracture and then reassembly. Yeah. -I don't know, man. It just makes me feel things. I just don't know what they are or what it makes me feel. It's like a weird science, art, mechanics, materials. -Right? These things ended up being gorgeous. I can see now what Cal was drawn to when he was imagining this before I could imagine it.

We also looked at them under the polariscope. This reveals the stresses inside the glass and you could see the folds as the glass was ladled in. And you could also see how the nose of the Prince Rupert's drop pushed aside that. And it ended up like in this amazing rainbow pattern. This is almost my favorite part. It looks like something in space, but it's got supersonic shock waves coming off of it. Like, it looks, I don't know. That's how my engineer brain interprets this.

There are two main things I learned in this video. The first thing was about the second order phase transition of glass. I didn't know that. And it's fascinating. And the second thing was about failure. Now, sometimes people will celebrate failure, and there's a place for that. But Cal has a unique perspective. When he's doing something really, really hard. The moment of failure means something different to Cal, and it was informative to me. A great piece is basically balanced right on the edge of failure and success. It's just, it's just balanced right there. But you don't really know how or where that line is. So you're very excited about that idea, it's spectacular to you. And you go and do it even though you don't seem like it.

You're going into it with a little bit of fear and trepidation to get too close to that line because you don't want to fail and lose it. But once you do fail it... all that's gone. Now it's game on. It's all about just learning, right? So if it's a piece that you know is going to take four and a half hours and at three hours, it's kind of screwed up. And you just say, okay, let's stop and start over. Well, you really don't know what happens in hour three to five. You have no idea. So when you get to three again, now, you have no idea what's coming. So my idea is usually if I screw up, screw it up all the way that I can to find out exactly what's hiding, what my intuition doesn't, what vocabulary of intuition has not been developed, what part of that language.

So now I've screwed it up, screwed it up, screwed it up all the way until the finish. We know where things might happen. So now, when I go back into it, I've got the intuition more developed. I mean, failure ends up being a good space for discovery, right? But it's like, if I'm going to fail, let's, let's keep failing, let's keep screwing up. Let's see what's there. Let's go find out. You know, like, but if you just stop and put it away and start over, you're kind of missing out on a lot. The fact that Cal and the team were able to figure out how to make a blue Prince Rupert's drop and how to cast it without melting it, I think that's amazing.

So if you actually want this thing, I've asked Cal if he'd be willing to sell it. He said, absolutely not. I can understand why. Because he loves it and I love it too. It's special to me. But I just asked him to put it up on his website, priced not to sell. This is one of the most fascinating objects I've ever seen in my entire life. It's this blend of fine arts and science and research and learning, and I just love to stare at it. I've had it for a few days, and if you'd like to buy it, you can do so at calbreed.com. You see, he signed it there. I think it's, I just think it's amazing.

So if you're interested in this, go check out calbreed.com. So it will be interesting to see what price he chooses. He also has other ones that he's going to put up there as well, some clear ones. And they have this ghost, I don't know how to describe it, like a veil. It's beautiful. So if you'd like to check that out. calbreed.com. And he also has figured out a way to cut some polarizing filters and to send those as well, which I think is really cool, and that makes it look neat.

I'm going to close with this 11-year-old email I wrote to Cal. I said, I would love the opportunity just to work on your crew for an afternoon or something. I would like to tell people about your website and where you're at so they can contact you to commission your work. I don't make anything from telling you to go to calbreed.com or orbixhotglass.com. This is just me trying to make good on an 11-year-old offer I made to a buddy, and I think it's awesome. And thank you to the patrons for allowing me to make videos like this. If you want to support Smarter Every Day, you can do that at patreon.com/smartereveryday. That's it. I hope you enjoyed this. Go check out Cal's website calbreed.com. It's absolutely phenomenal. This thing is beautiful. If you want to see maybe he has a few more he can make and put on his website. That's it. I'm Destin, you're getting smarter every day. Have a good one.