Secretly Incredibly Fascinating - Glow-In-The-Dark Stuff

Episode Date: September 8, 2025

Alex Schmidt and Katie Goldin explore why glow-in-the-dark stuff is secretly incredibly fascinating.Visit http://sifpod.fun/ for research sources and for this week's bonus episode.Come hang out with us on the SIF Discord: https://discord.gg/wbR96nsGg5

Glow in the Dark Stuff, known for being toys, famous for being like a light greenish. Nobody thinks much about it, so let's have some fun. Let's find out why Glow in the Dark Stuff is secretly incredibly fascinating. Hey there folks. Hey there, Ciphalopods. Welcome to a whole new podcast episode. A podcast all about why being alive is more interesting than people think it is. My name is Alex Schmidt and I'm not alone because I'm joined by my co-host Katie Golden. Katie. Yes. Katie, what is your relationship to or opinion of glow in the dark stuff? I always wanted to drink that glow stick, Alex. I know they say don't, but the glow stick seems to. to be saying yes do it right it's like wd40 it's a temptress of chemicals like ooh it's uh the forbidden the forbidden sauce i really want it uh looks really good yeah i like glow in the dark stuff i used to have those little glow in the dark stars in my room did you have those i did not and i don't feel like i missed out but they seem great you did you did you missed out big time just so you know

And I was also like all the way afraid of the dark, probably slightly longer than most kids. So I also just had the lights on for like a while. I see. Yeah. Well. Were you in charge of arranging and rearranging them? I always imagine people's parents just stick them up. I think I put them up.

I think maybe like my dad might have assisted by holding me up so that I could reach the ceiling. But I think I was the one, I was pretty insistent on putting them up. That's very cool. I like that a whole lot. My only other memory of glow-in-the-dark toys is I was not patient enough with dosing them with light. So then I would be like, why isn't this glowing? And I'd be told, like, you have to dose it more. And I'd be like, but why isn't glowing? It was just an irritating child, you know, very peripheral in my childhood.

And also absolutely a thing that's all around us in the modern day. And thank you to Leera 42 on the Discord. Layer of 42 suggests this topic. It ran away in the polls. What a wonderful pick by you folks. It's very siff. Yeah. And the only framing note is that there's an entire episode just in, like, man-made stuff that glows in the dark.

We're also going to include a lot of minerals and other raw materials because that's how you build some of that stuff. But we're going to skip astronomical objects. We're going to skip bioluminescence. That's kind of separate on its own thing. Whole other topic. This is about, like, toys and stickies. Toys. And many other things that glow, it will turn out.

Yeah. Yeah. Because all of us glow in the dark bioluminescence. But let's learn about our friends, the objects. And on every episode, we lead with a quick set of fascinating numbers and statistics. This week, that's in a segment called, I've always read numbers and the numbers that stats put me through. Been busted for stats that I did and didn't compute.

I'm really hoping you get recognized at the Kennedy Center this year, Alex. That name was submitted by Rob. Thank you, Rob. We have a new name for this segment every week. Please make a mycelian way I can be as possible. Submit yours through Discord or to siftpot at gmail.com. And the first number this week is about 600. Yes.

About 600. And that is the number of kinds of minerals on the earth that are recognized as glowing in the dark in some way. Ooh, that's a lot of, that's a lot of glowing, spicy rocks out there. Yeah, going into this, I thought it would be, like, only one or two things. But one key source this week is a feature for popular science by writer Lauren Leffer. And they interviewed experts, including Glenn Wichunis, a mineralogist who studies fluorescence and spectroscopy at Caltech. And Wichunas said there are more than 5,700 kinds of minerals on Earth, and about 600 of

them glow in the dark in some way. Cool. Which is neat. And it varies which light in what way, but like, it's never been hard to find some kind of raw material to make something that will glow in the dark. The trick is the best ways and the most effective ways. Right. So I know that in biology, there's two types of glow in the dark, which we're not talking about

biology, but I just want this as a point of reference. There's bioluminescence and there's biofluorescence. bioluminescence is there's actually a chemical reaction going on that produces light and biofluorescence is when you hit an object with UV light it converts that into visible light and shoots it back out at you so bioluminescence is like deep sea anglerfish right and their little bulb and it glows you don't need to shine a light at it for it to glow it's just a chemical reaction is producing that glow. biofluorescence is like taking a black light and all those recent marsupials that they found actually biofluores like you shine a light. But another famous one is scorpions with a lot of scorpions you shine UV light at them. They glow. It's very pretty. So with the minerals, like with all these rocks they find, because I assume there's not a lot of just rocks out there passively glowing by producing some chemical reaction on their own.

I assume you have to like, they're either fluorescing when you hit them with some type of light or you have to inject some kind of energy into the rock to get it to glow. You're right. And those are great touchdowns for this, yeah. Stones. Yeah, stones, ha. The giant number here is three. There are three broad categories of common ways that things.

glow in the dark. And with the rocks, it's usually two of the ways. It's either photoluminescence, which includes fluorescence, which is where we shoot a light at it and a different light is reflected by a phosphor. Yes. We'll talk about the word phosphor a lot. Phosphors are just stuff that receives energy and responds by producing visible light. That's nice of them.

It's very nice of them. The recent episode about cathode ray tubes, we talked about phosphorus being on the screens of like TVs and stuff. We like to set up phosphors. all the time. Either generate them or they're just naturally ready. I like it. I like stuff that when you like give them light, they're like, here's some cool effect instead of trying to give you cancer or something. Speaking of cancer, because the other big way rocks will, the other big way like rocks and minerals

will generate light is radiation. Radioluminescence is when there's so much energy coming off of something in the form of ionizing radiation that it glows. And one famous example is the element radium. Radium on its own will glow in the dark. Because it's like the reaction of the decay of the atomic decay produces the energy and shoots it out at you. And it's very pretty. But it's also like shooting electrons out at you, which is not usually good. Yeah, yeah. The very high energy of what we call ionizing radiation can damage tissue in living cells. And so that's why we worry about it.

Yeah. But, you know, their fellow rocks are like, I'm another rock, whatever. It's cool. Yeah. And it's interesting because we do use radiation therapy to treat cancer, but you can also get cancer from radiation. In the medical context, it's very targeted to try to destroy the cancer tissue. But when you're getting it from, say, the sun or from radium, it's not targeted.

so your whole body's just getting it. Yeah, also our recent sunscreen episode, we talk a lot about all sorts of life on earth trying to protect itself from the sun attacking it because part of the sun's light is attacking. So that's tough. Tough to be alive. But also, we can do it.

Stay uppeat. Yeah. Keep your chin out. Get your hippo goo and slather it on. And yeah, and so photoluminescence, receiving light, and then producing it or reflecting it. radioluminescence, radioactive decay is giving off the glow of ionizing radiation. And then the third big way is chemoluminescence.

And the big natural example is bioluminescence. This is pretty rare with just a rock that's sitting there. Right. And then the big man-made example is glow sticks. Glostics. It's its own scientific category. Glousticology, yes. Because, yeah, chemoluminescence is just in a different way from atomic decay, a chemical reaction producing energy, and then the energy is a glow.

Yeah. Because the, like, really mind-bending part of this whole topic is that a glow is energy. Mm-hmm. If it's in a particular wavelength that's visible to our eyes, that's visible light. Mm-hmm. Anything that glows in the dark, like, we don't think of the sun is glowing in the dark. we don't think of a fire is glowing in the dark. We're talking about stuff that has a surprising burst of visible energy from something happening.

Yeah, I mean, but in general, I think that's true. Like, light, right, does usually represent there being some energy being put into the system to produce the light, like photons have to get shot at your eyes somehow. Yeah, yeah, photons are being shot all the time. Right. If you're seeing something, photons. Wow. With tiny guns.

On a very small scale, yes, and that's how we see stuff. And glowsticks are a chemoluminescence that we've set up. Apparently, the first work in this happened in the 1960s. According to Chemistry World Magazine, it does feel very 60s of groovy. According to Chemistry World magazine, scientists discovered ways of making hydrogen peroxide glow by combining it with carbon-based compounds. So one of the main things in most closed sticks is hydrogen peroxide. You should not drink it. Really?

Yeah. Well, but you can swish hydrogen peroxide around in your mouth for oral hygiene. And then what do you do? Alex. And then what do you do next? Spit it off. Another brilliant rhetorical trap by me. Can't get out of that one.

I mean, it is cool because, like, when you, when you get a glow stick, it's unlike the glow and the dark stuff that you charge with light comes like, I mean, in stick form and then you got to crack it. Like, and the cracking is there are two compounds in the stick that are separated by something I don't know. And then when you crack it open, you're basically allowing the two substances to start interacting with each other. exactly yeah most closed sticks it's that plastic exterior that you're holding and that is containing a lot of hydrogen peroxide swishing around and maybe a fluorescent dye if they want a specific color but the two key ingredients are the hydrogen peroxide and then a smaller glass tube of something carbon based a common one these days is called diphenyl oxalate and so when you're cracking it you're like snapping open the the tube of the diphenyl oxalate? Yeah. Yeah, that's right. That's the name.

And yeah. All right. Yeah, that has a bunch of carbon atoms in its structure. And then they combine with hydrogen peroxide. And it's a one-time chain of chemical reactions that gives off energy, which lights up the die. And that's why it glows in the dark. Right. And that's also why you don't need to, like, put a glow stick under a lamp first.

You've just introduced the two chemicals. They play out the chemical reaction. And then it runs out of juice. And everyone's sad and goes home. Yes. Yeah, they're like, oh, why was that so slow? And then radio luminescence is a much, much longer one-time reaction. It's just, you know, like a thousand years or so of half-life or something. Yeah. Sounds normal and something I should definitely, like, rub on my skin. But the end of the show, radio and the human body will come up a lot. Oh, boy.

And then that third broad category of photoluminescence, another number here is two. because there are two major kinds of photoluminescence. They are fluorescence and phosphorescence. Tell me the difference. The difference is basically the timeline. With fluorescence, something receives and reflects light immediately and then pretty much stops after the light source goes away. Yes.

And then phosphorescence is when something slowly absorbs that light, slowly begins to glow, and then slowly winds down the glow. There's just more delay in the electrons and the photons going in there and then coming back out. Oh, cool. So fluorescence is like when CSI, Miami, takes the black light to the apartment and finds all the mystery stains, blood stains, and other bodily fluids illuminated by the black light. So that's fluorescence. And then...

Yes. Yeah. And black lights are sort of a special category, too. Right. And then phosphorescence is when I have my pretty stars and I charge it with my flashlight. That's right. Yeah. And so like phosphorescence is almost more our like cultural definition of glow in the dark.

Because fluorescence, you're just like lighting something up right then and glow in the dark. You're expecting sort of a lasting effect. Mm-hmm. And the other quick number here is around 2013. Around the year 2013, the U.S. government implemented redesigns for most paper money from the denominations of $5 up to have a security strip that glows under a black light. Since 2013, most U.S. money has glowed in the dark, especially the bigger bills. Blacklights are sort of a special category because they are almost radioluminescence. It involves shining ultraviolet light, but also even.

either blocking or filtering that so almost all of the dangerous ultraviolet light doesn't get to us. And so you're pointing the ultraviolet light at phosphors and then getting something out of it. They're popular as a thing for looking at stuff in a different way because they just excite a lot of natural phosphors and things. And synthetic phosphorus too, but highlighter ink, neon paint, tonic water, laundry detergents, and then also human teeth, fingernails, blood, urine, semen. A lot of man-made things and natural things just look interesting in the specific section of the ultraviolet spectrum that the black light's putting out. So if you're like trying to counterfeit money, you should pee on it. And then like when they're counting your money at the bank, explain to them,

I'm sorry, I pissed all over my money. Yeah. And so when it's like it shows up all wonky on the black light and they can't tell what's piss and what's the special symbol, then you're not going to be accused. You're not going to be accused as being a counterfeiter, but instead a money pisser. Exactly. Different crime feels good. Right.

I'm Googling. Is it a crime to pee on money? I just feel like it is, yep. It probably is. And yeah, and so this topic is kind of those three different things, photoluminescence, chemoluminescence, and radioluminescence. Receive light or do a chemical reaction or radioactive decay.

And then the subcategory of photoluminescence, which is phosphorescence, is the heart of our next takeaway number one. The look and the pale greenish color of most glow-in-the-dark toys comes from one of two compounds. All right. It turns out that especially a compound called zinc sulfide, it has a glow in that like very pale greenish color that we associate with glow in the dark stuff and that's why we just make a lot of things that color that glow in the dark it's a specific accident of minerals it was not a conscious choice to make everything kind of green yeah the light

that comes out of that compound happens to be kind of on the green spectrum I guess yeah and it was our most handy way to do like modern style glow in the dark toys. And then the second option is a relatively modern, I guess like upgrade. It's a more expensive and longer lasting glow from strontium illuminate. Ooh, it sounds fancy. Strantium is just a cool sounding element. And it also happens to have a color along the lines of zinc sulfide. And so that's part of why people ran with it is they said, yeah, it does the glow in the dark color. So great. Oh. Okay. I would think that innovation would be like we want more glow in the dark colors, not just like stick with the same kind of green one. But maybe is the branding really strong for that green color? Yeah, basically both have happened. Like the brand is strong and, you know, like with glow sticks or something, they do every color. Like we can do every color. It's just that that weird greenish glow, we tend not to have it in other stuff. And so it was sort of a fun.

for glow in the dark products to be in. Key sources are digital resources from the American Chemical Society and from the University of Illinois and also a feature for Chemistry World Magazine by writer Brian Clegg. Because the first big one here is zinc sulfide. It's easy to understand. It's one zinc atom and one sulfur atom bonded together.

Aw, cute. One zinc, one sulfur. Boom. That's what marriage is between. One zinc and one sulfur. Everyone's beautiful. marriage invalid. It's between a zinc and a sulfur. So sayeth the glow sticks. Yeah. And they're bonded together. They're also found in minerals all over the world. And starting

back in the mid-1800s, scientists and also companies started turning this into a phosphor for glowing stuff. This zinc sulfide, again, it's phosphorescence. So it's one of the kinds of photoluminescence. And you need to expose it to light. But then the way the structure of that zinc, and sulfur work together. They basically delay the electrons entry and then exit from that system. Right. So it's kind of like a drippy sponge. Sort of, yeah.

It's like still hanging in there. And the structures of other things just let these things go. So they don't go in the dark. All right on. The other like stuff we could dig into is the energy levels of electron shells. The super basic thing is that when the electrons get excited, they have the energy. to go one level further away from the nucleus and then come back later. And so if that goes slowly, we get a glow.

Yeah, I've had energy shells explain to me many times. It's never quite sunk in for me. I don't know, leveling up away from the nucleus. I keep wanting to have like a self-esteem metaphor or something. Like they're feeling bolder and so they go further away from the nucleus. But then that wears off and they come back. So I don't know. That's kind of, I'm just personifying electronics.

now. Stupid. No, but I think that's good. It's so hard to, like, have a good concept of physics and particle physics. I think doing silly stuff like that makes sense to me. It helps me. Good. It helps me, too. Yeah. And so, yeah, so zinc sulfide, it's not radioactive. It's not just decaying and making light. It needs to receive light and then phosphoresc it back out. Right. Again, lots of minerals can be turned into things that do this or are already things that do this. But zinc sulfide was widely available, easy to mine. And as manufacturers used it, they also got excited about the color.

Because zinc sulfide, it gives off a pale glow. And depending on how pure it is, it can either look whitish or a pale yellowish or a pale greenish color. It's all the colors I associate with the stars on a ceiling. Manufacturers can add any kind of pigment to zinc sulfide to get different colors. They also found that people were excited about this greenish color. color. And that's dominated the entire world of glow in the dark stuff. The only other compound that's come along to compete with it is strontium illuminate. With all these, you don't really need to know the structures, but strontium illuminate is one strontium, two aluminums, and four

oxygens. All right. So now we've got to expand marriage equality to this polycule. Polycule molecule. Yeah. It's seven atoms all getting weird. Getting weird with each other. Having a hard time solving interpersonal conflicts, but somehow doing it. Strontium never communicates. If strontium would just communicate. We could do this. Strontium has given the feelings whiteboard to be able to express itself. This is a compound that's been used for other things before it was used for glow-in-the-dark stuff. Apparently, it can be an ingredient in a cement that is extremely heat-resistance and good for, like, storing radioactive waste and stuff. But then scientists in the late 1900s, they discovered that if you add one impurity to strontium illuminate, you get something that does glow-in-the-dark phosphorescence.

For example, if you add europium. Europeium is an element named after Europe. It is number 63 on the periodic table. Well, was it found in Europe or discovered by Europe? Both. And a long time ago, when I looked things up about it, there's a lot of European Union flag beneath it, but it was the early 1900s.

They were just like Europe's cool and named it after it. Yeah. All right. And if you add Europium, you get not just a global. in the dark effect from strontium illuminate, but a very similar pale greenish color to zinc sulfide. And then also there's a much bigger molecule, this molecule molecule. And so it's very, very good at sort of slowing down that electron coming and going. And so it can hold a glow about 10 times longer than zinc sulfide.

I see. So it's a chunky molecule and it keeps the electrons from getting out. Yeah, the chunkiness and the lattice structure. The electron is like, wait, where's the exit? It's like when you're leaving the doctor's office exam room and you're like, wait, but how, okay, is that the desk? Do I, yeah. I, like, I was at the doctors and I had, like, it gives you a little ticket and you have to go to, like, a window. And then I was like, great. And then I see, like, there's like windows one through three.

And then my ticket is like, go to window five. And I was like, wait, what? But just wander into an operating room like, does everyone know where window five? is. And yeah, and so this substance is also a little more expensive, but if you ever see a toy brand that has super glow in the dark, that probably specifically means it's made with strontium illuminate instead of zinc sulfide because it will glow longer. I like super stuff.

I'd probably, I'd, I'd buy super glow in the dark over regular stupid poo-poo glow in the dark any day. I was really excited about learning this because, like, it doesn't seem like there's any regulation or laws about it has to have strontium illuminate to be called super. But I would have assumed it's even more of a wild west where just people are calling their stuff super. But that actually means that probably means something chemically and in the actual creation of it.

I guess there's probably, like if they say lasts for eight hours or something, there might be some law against you can't lie. about how long your glow lasts? I think so, yeah. But like calling it super, I think there's no laws about it, and it does actually probably indicate chemistry, which is neat. Right. It's great.

Cool. But both of these are still very common. Zinc sulfide and strontium illuminate, and they're both kind of that same color. And so things can be made to glow every color, but we've, through an accident of minerals and chemistry, picked this color for stuff that glows. Mm-hmm. Oh, so I like it. It's neat.

I'm not complaining. It seems like especially late 1800s and nobody was like really dyeing fabric this color very often, you know, it was just an open lane too and the whole deal of human products. Yeah, very, I mean, it's not got a lot of other applications, like a very bright pale green. I don't see in a lot of other stuff. It's hard. It's kind of hard to like separate though the color from the aspect of it glowing as well, if that makes sense.

Because, yeah, it's really the whole thing. Because when you look at like a dead glow-in-the-dark thing or an uncharged glow-in-the-dark thing, it's just, it's not, it's barely green at all. It's like kind of a pale hint of green-white color. Yeah, it's bordering on white all the time, yeah. Yeah. And it seems to have been really culturally influential, and we'll talk later about radium being the other green source. But we have another takeaway here because zinc sulfide and strontium illuminate are far from our first approach to glow in the dark stuff. Takeaway number two.

The first ever man-made glow-in-the-dark products was a Native American medication for kidney and urinary issues. It was a blue liquid. Oh, that's interesting. Do go on. Yeah. And if folks have heard passive episodes sometimes we talk about the Triple Alliance, that's a little bit more of an accurate name for the Aztecs. And the Triple Alliance, before the Columbian Exchange, came up with a natural remedy for urinary tract infections. Whoa.

And it comes from soaking a specific kind of wood in water. And you end up with a blue liquid that glows in the dark a bit. Hmm. Like, was the glowing in the dark thing where they were like, all right, this has to be science? Because, like, I'm looking at this. It's glowing in the dark. This has to have a science application. Or was that kind of like maybe just a byproduct?

We don't know. And our best guess is they probably were excited at glows in the dark and then tried to check if it has medical properties, which makes sense. That's exactly what I would do. That's what I would do. That's what I would do. Of course. It glows in the dark. Close in the dark.

Let's slap this everywhere. See if it cures acne or fixes your butt. And I like that they drank it too. That's bold. Right. Yeah, the medicine is drinking it, you know, and so. Does it make your pee glow? I don't think so.

No. Dang it. So mad about that. Like, it seems unfair that asparagus can make your pee stinky, but you can't drink this bark tea and have your pee glow. It's like, oh, yeah, the bonus of the copper show we talked about Manhattan Project guys talking about their pee being radioactive and feeling that. Yeah. Yeah, this is an amazing story, and key sources here are digital resources from the University of Texas at El Paso, also a gardening guide from the San Antonio, Texas city water system, and then a wonderful recent episode of SciShow on YouTube hosted by Hank Green. Nice.

But it's all about a North American genus of plants. It's endemic to what's now Mexico and the southwestern U.S. They are small, leguminous trees. Leguminous. Yeah, the Latin scientific name is Eisenhardia, but the more common name is kidney wood. And people in the Triple Alliance turn this plant's wood into a medicine they called Coatley. And it's pretty simple. You just chop up wood chips or leafy branches of the tree and soak that in water for a few hours. That's the whole process. And I assume something leaches out into the water, some chemical that is also glow in the dark.

Yeah, it's pretty much chemoluminescence because what happens here is the water and the plant matter combines in an oxidation process to make a new substance that glows. That's pretty cool. Yeah, like the substance and the energy of the reaction, you get a glow. And quoting UTLPASO here, this interesting phenomenon is due to a novel four-ringed chemical compound known as tetrahydro-Methonobenzoforo-oxocene. Yeah, that. If you're listening at home, that was like the fourth try, me saying that. I cut out the others. He's being modest.

That was the second try. He almost said it. Continuing UTL Paso, that compound is not found in the intact. I see. But rather is the end product of an unusual spontaneous oxidation involving some of the plant's natural compounds known as flavonoids. Flavanoids. On the sunscreen episode, we talk about flavonoids protecting plant leaves from some of the

radiation of the sun. In this kidney would process flavonoids in the wood or in some of the leaves react with the water. And both the energy and the new oxidation creates a blue glow in the water. So it's kind of like how, like, water, when it interacts with, say, iron or something can produce rust. Because that's also an oxidization process. Yeah, exactly. Yeah, and you get something new and energy is transferred.

We don't have an exact inventor. We don't know the exact process. But we think Native Mesoamerican people made glowing blue water. You know, you have some wood and some water sometime. And you're like, wow. And then said, let's figure out what it does. and it has documented antimicrobial properties. This is not just a folk belief or a placebo.

Oh, dang. We do think there was some folk belief around it as a general tonic, but it has specific properties to treat kidney inflammation, urinary tract infections to improve urinary flow, like that one element of how the body works. It's very, very helpful. And around what time period was this? Because I think I always get messed up with Aztec,

timeline because it's a lot more recent than I had thought initially when I was learning about it. Probably less than a thousand years ago, but it's before the arrival of the Spanish in the 1490s. Okay. Because, yeah, and then the peoples who became the Triple Alliance were existing before they formed that governing situation, but really the 12 and 1,300s, they start to form that.

Okay, yeah, that makes sense. And yeah, and then when Spanish military is invaded, they, just copied and borrowed this and brought the Coatley medication to Europe, under various languages, the English name Kidney Wood became common. And Europeans also used this for kidney problems, both because it works and it glows in the dark. Yeah. It's wonderful branding and effective. Yeah. It's like, we must take over from these primitive folks. Also, here's their glowing medicine. Yes. So, yeah, that in its way is to me, the first glow-in-the-dark product in the world.

Yeah, like people putting something together to glow in the dark, and you never hear about it ever. Yeah. And folks, that's two takeaways and a giant number section. We're going to take quick break, then return with a few more takeaways about people making stuff glow in the dark. Hooray! We're back.

And our next takeaway is sort of a follow-up to the previous. one because takeaway number three the second ever man-made glow-in-the-dark product was a rock that an alchemist hoped would make him immortal yes yes and this is something that the guy called bologna stone that's very good it was mine from a dormant volcano near bologna that's what i want when i'm thinking about like a stone that might make me immortal. I want to call it the Bologna Stone. Yeah, I'd say only in the last few years have I learned that it's pronounced differently from Bologna in some situations, but calling it Bologna Stone in an American voice is

pretty accurate to the hope that it'll make you immortal. Oh, you have a Bologna stone for that, sure, yeah. Because the meat, those meat cutlets did sort of originate from Bologna, a variant of them, different from the Oscar Meyer. amalgamation of today. We should do a bologna episode. That'd be so good. We'd be a really good out.

Yeah. We already did spam. We got to do bologna. It's actually true. Oh, now I want to eat lunch meats right now. Okay. I don't. Pulling it together.

I'm glad. I'm happy for you. Thank you. But yeah, the key sources here are a feature for the former website I.09. That's by science journalist Esther Inglis Arkell. And then another feature for Knowable magazine by science writer Kurt Kleiner. Bologna Stone, it's from 1603. So it's after the Kuatli medication and also a totally different thing.

This is people treating a mineral to make it a specific glow-in-the-dark item. So it was not just a glowing rock he found. He actually made it glow-y? Yeah, it's a little of both, but he did stuff. And he did it because he was an alchemist. There's an Italian alchemist named Vincenzo Cascariolo. Yeah, he is. And he discovered a deposit of rock at the base of a dormant volcano near Bologna.

And the mineral was a relatively known mineral. It's called Berrite, which is a combination of barium, sulfur, and oxygen. I know there's been a lot of chemistry and geology, but you don't really need to know what it's made of. The key thing here is that a few hundred years later, scientists figured out why this rock was special. they found out it has specific additional copper in it, and that's why it's different from other Baywright. So the copper would encourage some kind of reaction? Yes, it made it a lot more phosphorescence.

And Cascariolo's goal was, I don't really know any chemistry or geology, but I want to find the philosopher's stone. Perfect. You're hired. Perfect. You're hired. Exactly. Everyone in 1600s Europe is like, me neither, man.

Perfect. I don't know chemistry. You're hired. I also don't know geology. Stop talking. We already hired you. You're a white man. You're in. Come on. Come on, Vicenzo. Kaskariolo wanted to find the philosopher's stone, which it was a dominant mythological idea among alchemists. It's either a rock that turns base metals into gold or turns liquids into a potion that makes you immortal. Right, right. Yeah. And they do. just kind of, they had no evidence for this existing. They just were kind of like, that'd be neat. Yeah, everybody just hoped so hard that it would exist. Yeah. That it became like a common

piece of wisdom that truly it exists. Yeah. It's one of those things. It's like, what's the cool thing or rock could do? It could be your friend if you draw little eyes on it. It could make you immortal. And only one of those ideas lived on. The pet rock, our mightiest idea. The pet rock. Dude, do they have like pet glow on the dark rocks. That would be cool. That'd be really good. That'd be very cool. And because he was in this alchemist mindset,

Cascariolo heated the weird bearite from Bologna, and he didn't get a philosopher's stone situation, but he unknowingly caused a chemical process called calcination, where heat and oxygen and the other gases in air changed the chemical properties of the rock. and after he did that, he could dose his new rock with sunlight or with the heat and light of a flame. And then after that, the rock glowed in the dark for many hours in a phosphorescent way.

Got to be immortality. I'm telling you, Alex, I think the instinct to immediately put glowing things in your mouth to try to become immortal is normal and it's fine that I felt that way. It's deep within all of us. Yeah. Inside us are two wolves, and both of them want to eat glowing stuff. They're both going like, yeah, yeah, yeah, yeah, do it, do it, do it, do it. Fully in agreement, the wolves.

Those were great wolf voices. I really like that. So, yeah, and Kaskarillo named this Bologna stone because he found it near Bologna and didn't know anything else about how he made this happen. It's great. And he also was doing this before we had words for things that glow in the dark and the way we do now. Now. Like the trope of the phrase glow in the dark as a name just wasn't going yet. We hadn't coined that because there wasn't enough stuff that glowed in the dark. And we also didn't have the name fluorescence yet. That got coined about 250 years later. Right. That was after we got Florence. And then we could be like, this is florencense.

Yeah, fluorescence came from a British physicist in the 1850s. His name's Sir George Stokes, and he was studying stuff like how fluids and salads and viscosity works, kind of as a side project worked with ultraviolet light and tested UV light on various minerals and saw it either went through or reflected. And he coined the name fluorescence based on how UV light interacts with fluorite, the mineral fluorite. So we didn't have that till the 1850s as a word. Pretty reasonable. Not as cool as baloney stony. But, you know. Yeah. And in the early 1600s, he had no words for what he made, really. He was just like, what am I near? Great. And it doesn't seem like Aztec medication for your

kidney. So that doesn't work as a name. I thought it was going to be something dumber. Like, let's see. I found this on the floor and it has a glowing essence. It's a floor essence. It's not spelled right for that, though. I wouldn't put it past these guys. I found this rock on the floor. Floor right. But yeah, and it took until really the end of the 1800s for us to call anything glow in the dark,

for there to be like enough things that that's a category in our heads. And the most tragic spark for that is takeaway number four. A group of young American women nicknamed the Radium Girls ended a myth that glow in the dark things always have health benefits. Yeah, I watched the world's most depressing documentary on this one, Alex. Yeah, and I... The whole thing is going to make... Like, it's the whole thing just every step of the way makes you cringe,

because you know what's coming and you're just like oh god no they did what no oh no we're both going to cover this and also keep it somewhat quick because the key source here is a book called the radium girls by an award-winning nonfiction writer named kate moore and the other one is digital resources from the new york historical society because this story is around like newark new jersey orange new jersey the the new york city area but yeah also there's documentaries about this there's a Netflix show about this. So I want people who've never heard it to know it. And also it seems to be out there.

Yeah. It's a truly wild medical tragedy. It's fascinating. It's a fascinating story. That's why I watched the documentary. But it just is the whole time. It's like we know radium is not really healthy for you. And then as you go through all the stuff they did with this radio, it's just like, oh, God, no.

Exactly. Like really the first quarter of the. 1900s, a lot of people in, especially the United States, thought that radium is nothing but good for your health. It's glowing. And that you should be, like, receiving and consuming the glow of radium any way you can. I mean, like, stuff that glows just seems like it'd be good to put in your mouth, man. I don't know what to say.

It's not always true, but it feels right, except when it's really, really, really wrong. Yeah, they had the two wolves inside them. I relate completely. Do it, do it, do it, do it, do it. Yeah, and this starts in the 1890s, a few European scientists amaze the world by isolating some new radioactive elements. And the key ones are the married couple, Marie and Pierre Curie, French and Polish scientists, who isolated polonium and then isolated radium in 1898. Kind of their fault for their name being Curie, like, we're going to cure your illness, is he. cure your sickies with our glowy stuff.

The other crucial thing is this led to experiments in what Katie described earlier of radiation can kill tumors and mitigate cancers and it has medical use. But then because of that fact and because radium is fun to look at when it glows in the dark, people in the U.S., especially due to unscrupulous companies decided radium is a magic health substance and you should buy every product. with radium possible. Yeah. And, like, be around it and exposed to it and consuming it. The claim was not just that it's neutral for you. It's that it will, like, pep you up and make you healthier and make you, like, cosmetically more beautiful.

Right. My favorite example is radium water. Oh, yeah. I'm looking at this ad. This is wild. Drink radioactive water. Because it's just a jar lined with radium that's basically, like, a water cooler. And you were supposed to purchase the jar, fill it with water, and then drink five to seven glasses of radium water per day.

Oh, boy. And it was nicknamed Liquid Sunshine. Oh, boy. Did it actually make the water radioactive? Because, like, in this case, if it was just a complete scam, that would be good. Yeah, that's a perfect question because this ending is kind of two takeaways. The other takeaway is takeaway number five. The companies promoting radium scammed their own customers in a way that accidentally protected them and advanced glow-in-the-dark technology.

Oh, that was the plan the whole time, Your Honor. The one huge piece of good news here is that Radium got so popular and so expensive. A lot of companies just used other stuff that glows in the dark and accidentally saved, like, so many lives. Your Honor, we did that. That was on purpose. We call it a... Yes. We call it a salutary scam. It's so, you know, in the business, just trying to help people. I'll make money.

The economics of this are wild because, again, it was discovered 1898. By the first decade of the 1900s, everybody wants it. Radium's being put in everything from jockstrapes and lingerie to butter, milk, toothpaste, cosmetics, bug spray. household cleaners. You can't breeze past that. Alex, why? Why were they putting in? Like, so your jockstrap would glow?

So that the radium would infuse you in a way that makes you healthier. Down there. Even though we know today it might make you infertile or something. But like... Down in that region. All right. But they thought the complete opposite. It would make you amazingly fertile and healthy and great.

It's so interesting because. And I don't want to derail this too much. But there's like, again, please don't take this and run with it, RFK Jr. That we should be irradiating people. But there's like some research into whether extremely low levels of radiation actually help increase antioxidants in your body. So it's like, which again, it's like, please don't RFK Jr. try to radiate Americans because of this because like the the key thing is like radiation

can be wicked bad for you but like there is like some there's like a concept that like actually if you like a low enough dose of it you might actually be able to get some protective benefits from because it might increase the production of antioxidants none of this is like none of this is like ready for people to start dosing themselves with radiation that would be very bad um but it's like there's it's it's really interesting to me when you have these historical events where it's like people are like oh this might have some health benefits and it's like yeah actually once you do go into really specific research about it and learn thoroughly about it you can find what potentially are the health benefits but drinking a bunch of it

is not going to do it. Exactly. And these companies are clearly just grabbing radium as a brand. Right. They're just, we make X, so let's add radium to it. And X could be anything in the whole world. X could be jockstraps, butter, hats, whatever, you know? Pokemon cards.

And it really was a fad. Everyone talked about radium being like the secret to all health and psychological joy. in the world. In 1904, there was a Broadway musical where their smash hit song was called the radium dance. It was about how lively radium makes people. Okay. I mean, like, so we know that radium can destroy you on the cellular level. Does it actually make people, like, energized in any way? Like, what was the base? Okay, so there's no, like, caffeine element to it that actually made, it's all psychological. Yeah, it's all psychological, and it's partly the glow.

People were like, if it glows, it's got to be magic. Like, if it glows and one doctor is talking about it for tumors, it's probably magic. That was the thinking. Yeah, I would have fallen for that. So many people did, Eds. The stats that we have are from 1917. In 1917, radium was the most expensive substance on Earth by weight. Oh, wow.

commercially. One gram of radium cost $120,000 of old-timey U.S. money. That's a lot of money. Millions today. Because, yeah, yeah, that's a huge amount of money. And one gram goes a long way for a lot of products, but that meant that all the products started costing more and more money. Like the radium water jar costs $200 of old-timey money. That's several thousand dollars today. Good God, yeah.

And so there became a massive commercial incentive to not actually use radium. Right. That you can charge the radium price for something with zinc sulfide in it. Yeah. Yeah. Because that doesn't glow quite like radium does, but nobody really knows anything about radium. So you can just sell them something with zinc sulfide. And if it hasn't been in the sun for a while, they'll just think, oh, I guess my radium's not that bright or something.

Yeah. We didn't have Wikipedia at this time. Yeah, we don't know. So, you know, we don't know anything. Yeah. Then the other thing we tragically did know pretty much right away is that radium is bad for you. Oh, okay. So, but then, Alex, hang on.

I don't understand. Why would companies continue to sell radium if we knew pretty immediately that it could be really bad for you? I don't understand. Katie's doing her sincere voice and face. Very sincere. The Curies, apparently after they discovered radium, gave a few of their scientific friends gifts of little vials of it. And in 1901, their friends, a physicist named Henri Beccarell, he left the vial of radium in his jacket pocket and forgot about it. And he realized he still had it when he started having a big growing burn on that part of his body.

Oh, boy. And then also, a guy whose reputation is not great these days was on the right side of this. In New Jersey, the scientist Thomas Edison made sure to handle radium with tongs. He wore like protective lead clothing. And he told people that, quote, there may be a condition into which radium has not yet entered that would produce dire results. Everybody handling it should have a care. Like you electrocute one elephant. And everyone's like, there goes Mr. Elephant electrocutor, but you warn people of the risks of radium.

And it's not like, oh, look, it's Mr. warns people about radium. Yeah, it's cancel culture plus elephants. Run amok. Run amok. Special interest elephant groups. But then, like, down the street from Edison, there's a U.S. corporation in Orange, New Jersey, that hired armies of young women to paint radium onto the faces of watchdiles. This is the worst. This is like the worst element of this.

Yeah, element. Ha-ha. Oh, I wasn't trying to be funny, Alex. I know, I know. And this is where the nickname of the Radium Girls comes from. They were young women, mostly Italian immigrants or daughters of immigrants. And they were supposed to paint Radium onto watchtile faces, also the gun sights and markings on various military equipment. Right. Because you get a glowing interface without.

out any need for photo luminescence. It's radioactive, so it glows. And actually, if I remember correctly, the amount of radium that would go on to the watch face was so small that the actual customer was not necessarily in that much danger. It was the girls in the factory exposed to this day and day out in ways that were so spectacularly irresponsible, not on their part because they're told it's safe. One detail is they were told specifically to like wet the brushes with their lips to get a fine point on the brush so they could use it to draw on those lines on like the watch face

and it's like oh but if you get a little bit of the radium in your mouth it's fine because it's good for you exactly yeah it was a very terrible combination of all those things because everybody believed radium is neutral or positive for your health and the ladies were taught to lip dip paint Oh, boy. Use your lips to narrow your brush into a perfect little point and then dip it in radium paints and then paint it on the watch.

And don't wash it between these. Just keep going. It's funny because for me, lip and dip means something very different. It's like when I give someone lip where I'm like, where do you get off, buddy? And then I dip before the consequences. And then paint a beautiful watercolor. Unrelated. It's just a third step.

That's just how I process my emotions. And yeah, and there were also, like, competing European companies where they didn't quite do it this way. There was a Swiss facility where the people used solid glass rods to put radium on watches. There was a French facility where they used small sticks with cotton wadding on the ends. Other facilities used a sharpened wooden stylus or a metal needle. It was this one business where it was paintbrushes that you put in your mouth. Yeah. That's not going to be good.

And also, like Katie said, the customers were okay because in order to have radium-based paint, only a truly tiny amount was radium. A lot of the rest was phosphors that reflect its light. And then the most acute problem for them was they were putting it in their mouth all day constantly. And also human bones and teeth absorb radium easily. Oh, boy. In a process similar to the absorption of calcium, which is good. Yeah.

And so as waves of these girls died of an uncurable poisoning, the press began calling them the radium girls. There were lawsuits. There were studies. It went to the Supreme Court in 1939. And then also there was another similar factory in Illinois where the staff were told, just don't consume it. Radium's still totally safe. And then in the later 1900s, that whole group of employees got sick in their own way. Oh, no.

Yeah. And so it's taken a lot of. time for people to understand that a glow in the dark from radio luminescence is dangerous unless you really shield it and handle it well. It was also just very gruesome because it wasn't just, I mean, of course, dying is gruesome, but a lot of the girls would get basically like they would, because of what you said, where it would get absorbed into the teeth and the bones. Yeah.

Their jaws would, the bones of their jaws would start to decay, essentially. Yeah, it was the first spot for a lot of them, yeah. Yeah, and so you would get, they would start to just need to have chunks of their jaw removed because their jaws were decaying from being exposed to this radium paint. Exactly. And newspapers could print photos in the 1900s, like this horrified the country. Everyone was like, oh, the radiative. Fad needs to end.

The parrot takeaways here, the other one is basically companies that did an evil thing and cut corners on the safety of their workers. Some of those companies did another evil thing to their customers of scamming them and not actually giving them radium. Yeah. And if they did that second kind of fraud and malfeasance, it accidentally protected everyone. Yeah. It's so weird.

That's so incredible. I mean, that's got a, that must happen all the time now, right, where gammy health influencers sell you their like colloidal silver, but it's actually not colloidal silver, so you're fine, but only because it's a scam. I'll bet, right. Like, silver seems expensive, so probably, yeah. Right, yeah. It's also not something you should drink. Yeah, don't do that. But, like, yeah, if someone's already scamming you with fake health products, they'll probably give you a cheaper version, too. Like, like, sure. That's just a second scam. It's scam on scam. Right. Yeah.

The scams cancel each other out and become neutral. And so then fake radium uses became one way we developed better glow-in-the-dark products. And initially, zinc sulfide was kind of a king of these. And then also in parallel, just the entire electronics industry happens. And so then we get products that light up in an electronic way. And that decreased the need and interest in glow-in-the-dark stuff, too. Yeah, some of our best innovation comes from war and scams. Which are kind of the same thing, am I right?

Take that, the generals. Hey, yo. Take that. Hey, what if there was a war? But we all just hung up on the scammers, eh? Huh? Yeah? And I think like they no longer use radium for watch faces, right?

Because I think like they did for, after this, they did use it for a while without the trying to mitigate the workplace dangers of getting it in your mouth or on your person. But yeah, I think now I don't believe it's used anymore. We're basically depending on regulations and safety. And this Radium Girl's story was so nasty. And then it's a town called Ottawa, Illinois that Kate Moore writes about had like the next horrible factory where they didn't eat it. it as they made it, but it was still not safe and still harmed people. Right. So those Paris scandals kind of ended this.

At least it did. And there weren't a bunch of radium truthers who were like, it's actually still really good for you. It does absolutely feel like our FK stuff, like that and tobacco and whatever else. It's going to just roar back, yeah. Yeah. But not for me. I don't need it.

I, yeah. Inside of me is a third wolf who's making sure I don't do that thing. But like, so Alex. You did say that the glow in the dark stuff was safe. And that the scammers by giving their customers glow in the dark stuff versus radium protected them. So what you're saying, what you're saying is I should be drinking this glowing gogurt. There's just like a little ticker of evil money going up as we say these things. Your own words, Alex.

Folks, that's the main episode for this week. Welcome to the outro with fun features for you such as help remembering this episode with a run back through the big takeaways. Takeaway number one, the look and the pale greenish color of most glow-in-the-dark toys comes from one of two compounds, zinc sulfide or a more recent longer-lasting thing called strontium illuminate. Takeaway number two, the first ever man-made glow-in-the-dark product was a Native American medication for kidney and urinary issues. Takeaway number three, the second ever man-made glow-in-the-dark product was Bologna Stone, a rock that an alchemist hoped would make him immortal. Takeaway number four, a group of young American women nicknamed the Radium Girls, were a tragedy that ended the myth that glow-in-the-dark things have health benefits no matter what.

Interlocking with that, takeaway number five, a lot of companies selling and promoting Radium also scammed their own customers in a way that accidentally protected them from radium and advanced glow-in-the-dark technology. And then a ton of numbers before and during those five takeaways, especially about three broad categories of common ways of making things glow in the dark. Chemiluminescence, photo-luminescence, and radioluminescence. Those are the takeaways. Also, I said that's the main episode because there is more secretly incredibly fascinating stuff available to you right now if you support this show at maximum fun.org. Members are the reason this podcast exists, so members get a bonus show every week where we

explore one obviously incredibly fascinating story related to the main episode. This week's bonus topic is two stories of teenagers teaming up with a very specific parent to do something amazing with glow-in-the-dark stuff. Visit sifpod.fodd fund for that bonus show. for a library of more than 21 dozen other secretly incredibly fascinating bonus shows and a catalog of all sorts of Max Fun bonus shows. It's special audio. It's just for members.

Thank you to everybody who backs this podcast operation. Additional fun things, check out our research sources on this episode's page at maximum fun.org. Key sources this week include a book called The Radium Girls by award-winning nonfiction writer Kate Moore. Also tons of digital scientific resources from the American Chemical Society, the University of Illinois, the University of Texas at El Paso, the New York Historical Society, and then tons of excellent science writing from I-09, Knowable Magazine, Popular Science, and more. That page also features resources such as native-lashland.ca. I'm using those to acknowledge that I recorded this in Lenape Hoking, the traditional land of the Muncie Lanoppe people and the Wapinger people, as well as the Mohican people, Skategoke people, and others. Also, Katie taped this in the country of Italy, and I want to acknowledge that in my location and in many other locations in the Americas and elsewhere, native people are very much still here. That feels worth doing on each episode and join the free SIF Discord, where we're sharing stories and resources about native people in life.

There is a link in this episode's description to join that Discord. We're also talking about this episode on the Discord, and hey, would you like a tip on another episode? because each week I'm finding is something randomly incredibly fascinating by running all the past episode numbers through a random number generator. This week's pick is episode 194. That's about the topic of the euro, the currency. And fun fact there, Lithuanian college students celebrated the beginning of the euro in Lithuania and also the end of their previous currency by building a giant memorial pyramid out of the penny coin

and the old Lithuanian currency. So I recommend that episode. I also recommend my co-host Katie Golden's weekly podcast Creature Feature about animals, science, and more. Our theme music is Unbroken Unshaven by the Budo's Band. Our show logo is by artist Burton Durand. Special thanks to Chris Sousa for audio mastering on this episode. Special thanks to the Beacon Music Factory for taping support.

Extra, extra special thanks go to our members. And thank you to all our listeners. I am thrilled to say we will be back next week with more secretly incredibly fascinating. So how about that? Talk to you then. Maximum Fun. A worker-owned network.

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