Stuff You Should Know - How Aerosol Cans Work

Episode Date: May 16, 2013

In the 87 years since they were invented aerosol cans have protected soldiers, temporarily fixed flat tires, killed a boy who used too much deodorant and had their contents banned by most countries for wrecking the ozone layer. Tune in to learn more. Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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Hey, everybody, do you ever scream at your printer or hurl empty ink cartridges across the room? We all do, which means that you likely suffer from cartridge conniptions caused by irritating ink cartridges constantly running out of ink. It's the worst, everybody. We can all agree on that. But thankfully, the Epson EcoTank Printer is the perfect cure.

It's cartridge-free, conniption-free, and prescription-free. With big ink tanks and a ridiculous amount of ink, you can finally kiss expensive ink cartridges goodbye. Yeah, so check out the Epson EcoTank. Just fill and chill. Available at participating retailers and at epson.com. Welcome to Stuff You Should Know from HowStuffWorks.com. Hey, and welcome to the podcast.

I'm Josh Clark. There's Charles W. Chuck Bryant, and this is Stuff You Should Know, the podcast. Yeah, are you excited about this one? I'm going to try to be excited for everybody, enough for everybody. Because I imagine there's a lot of people out there who don't listen to every single episode.

Sure. I find that biting and weird. Because I- I do that with my podcast, though. If I'm listening to, like if I look at Mark Maron's, I listen to that one. If it's a guest that I'm not super into, I want to listen to- Sure, sure.

Other podcasts. I'm talking about Stuff You Should Know, man. Gotcha. You must be confused. Yes. I feel like every single one of them is worth listening to. Agreed. I suspect, though, that people are going to skip over this one.

Well, I am going to take the wrap, because I picked this one out. I like it. But as I looked into it, I was like, you know what? I don't know how an aerosol can work. Exactly. And I would like to- And it's not super, you know, complicated.

It's not. And as a matter of fact, now that you read this and researched it, you understand how an aerosol can work. You can go to the hardware store on a Saturday when you're bored and just stand around and explain it to people and get applause. I could do that. Anyone who listens to this episode

will be able to do the same thing. Yeah, but it'd be like Ace Hardware, and there'd be some 75-year-old guy with a red vest next to me. I'll piss off. Yeah. They always have old-timers working there. Yeah. Well, they are big on keeping the economy going

on the backs of aged baby boomers. Isn't that their slogan? Yeah. I think it's Ace is the Place. Yeah. Well, you have to read between the lines. Yeah. Chuck, have you ever seen a movie called Style Wars?

It's a documentary from 1983. No, I haven't. It's pretty cool, man. It basically chronicles the rise of graffiti. I was about to say hip-hop. Clothing and stuff. And break-dancing. OK.

Just that whole culture. Yeah. And it's amazing, the stuff that people were doing even back then, as far as graffiti goes. And break-dancing and hip-hop and all that. Sure. But it's just like the seminal documentary that you just kind of have to see.

It's just so cool. It's like it kind of makes you feel cool watching it. You know what I mean? Well, I need that in my life. But the reason I raise Style Wars is because the graffiti that was being carried out would not have ever been able to be done. Had it not been for a Norwegian engineer named

Eric Rothheim, who in 1926 put in the first patent for an aerosol can in Norway. And then five years later, the first one in the US. Yeah. And they have a little photo of some of his initial drawings. And the author of this article points out that although it has evolved somewhat, he was pretty right on with that first design.

Right, you know? Almost out of the gate. Yeah. Because, as we said, it's kind of simple. Yeah. One of them was simple to me. One of them I didn't quite understand. Well, OK, so Rothheim, he comes up with this patent, files it,

kicks back and waits for the money to come rolling in. But it doesn't. It took many, many years, 15 or so, maybe a little less, before anyone fully understood the value of an aerosol can. And it was insecticides, bug bombs, cans of insect spray that was being used by soldiers in the Pacific in World War II, when people finally said, oh, that is a good idea. Yeah, I wonder if, I mean, they had atomizers and things

at the time. I wonder if that was his initial inspiration, was to take that concept and jam it into a can, basically. Yeah. Because that's what's going on. Yeah. You're atomizing a product. Yeah, and there's a lot of advantages to atomizing.

Number one, if you spray something in a fine mist, it doesn't hit the ground as a bunch of liquid that seeps into the groundwater, usually sticks to whatever you're spraying it to. Sure, and it's delightful if you wear perfume. Or have you ever had the rosewater sprayed on your face, like the face sprays? Oh, I thought you meant like an aerosol can of perfume.

Oh, no, no, no, no. Atomizing, in general. Yes, sure, sure. I'm not, I've had an avion spritz sprayed on my face. You mean I have before. It's very nice. Yeah, I've had the rosewater. Emily will spray me occasionally.

That is very nice. It just feels good. Does she like hide behind it around a corner and it's. Yeah, no, that's the mace. Oh, she maces me occasionally for kicks. So yeah, there's advantages to atomizing things. There's reasons. At the very least, it's lovely.

It is. And the whole premise behind this, though, the delivery method of an aerosol can, like we said, it's very basic. It's very old. And all you have to do is understand a little bit about fluid dynamics to get what's going on. So let's give a brief primer on fluid dynamics, shall we? Yeah, and fluid, period, like, you know, fluid isn't

necessarily liquid, like you might think. Right. It's an actual thing. Fluid is any kind of substance that has free flowing particles that's made up of that, and it could be something liquid, could be something gas. Those are both fluids. It just can't be a solid, basically.

Pretty much, yeah. As long as you've got those free flowing particles, these particles, if it's a liquid, they're loosely bound, but they're still bound. So it means it's going to have a fixed volume if it's a liquid. Yeah, which is why when you put water into a glass, it doesn't just keep going and going and going. That'd be terrifying.

No, it would have a gaseous characteristic, then. That's right. Because gas does expand to fill the volume that you put it in. That's right. And, well, spoiler alert, that's what happens with gas. It expands. If you heat liquid, applying energy to it, basically, it's

going to vibrate, and it's going to break those forces, and they're not going to be bound together anymore, then you're going to have a gas, and that's called boiling. Yeah, and we think of boiling as applying enough heat that you will burn your skin. But boiling points vary for different types of fluids. So any volatile fluid is a fluid that boils or turns from a liquid state to a gaseous state that's boiling at room

temperature, right? Yeah, which that's the part I had a hard time getting my head around, because I associate boiling with heat and hot. Yeah, because you think of boiling, you think of water. Yeah, exactly. And it takes a certain amount of heat energy to break those intermolecular bonds to turn water from a liquid into a gas. That's right.

But it takes less for alcohol or for propane or whatever you want to use, right? And so lastly, there's another fluid dynamic trait that we have to have down, and then we'll have all of the stuff in place to understand an aerosol can. Expansion of gas? Yeah, so we said that when you put gas into something, it expands to fill the volume.

Yeah, and gas will decrease in pressure as it expands, which is why a tiny little CO2 cartridge has tons of pressure in there, and that's why it can shoot your awesome industrial arts model car down the track. Right, because. Did you ever do that? No. Really?

I had a Pinewood Derby racer once. What's that like, the car you sit in? No, that's the Cub Scout car. Oh, OK. It didn't have any CO2, though. You'd be immediately disqualified. Yeah, in high school, we made the little cars that have the CO2 cartridge in the back.

Oh, I know what you're talking about. And we raced each other. Nice. My brother won county, of course. Yeah. And then. And then flashed this winning smile. And three years later, it's so funny, I forgot all about this.

I tried to copy his car design when I took the class, and mine was not nearly as like, it just wasn't quite right. And I didn't win county. I didn't even win my classroom. Somehow, the compressed air decompressing into the atmosphere made a sad trombone sound. It was so cool. And that really just sums it all up with my brother and I.

He was always really great at stuff, and I always tried to do that, and was not nearly as good at it. You're good at other things. Well, yeah, I can run my mouth. If that's how you want to put it. Anyway, so that's compressed gas. And when gas is compressed, it can do some great things, like shoot the car, or in this case, spray paint or something.

Right, right. Exactly. OK, so you have compressed gas. You have all these fluid dynamics, and you've had everyone now, right? Yes. OK, so all in aerosol can is all of these principles kind of put into a very simply, mechanically functioning

state, right? Yeah. So you have a can, and you have two things in there. You have the propellant, which is the stuff you use to force the other thing, the product out. Yeah, and it could be hairspray, bug spray, could be paint, could be that foamy stuff. You ever use that?

The stuff to seal insulation or something? Yeah, or fix the flat, all that. It has myriad, myriad uses. OK, right. So you've got the product in liquid state. Yes. Say it's just kind of floating in the bottom of the can. Sure.

You put it in the can, seal it. So there's no air going in. It's airtight. Yeah, this is part one. There's two ways to do this. This is the first one. Right, this is the simple way. And then you add some sort of compressed air to it.

Call it air. Compressed air. OK. OK. So you have the propellant in there, and it's basically filling up as much as it can until it's reaching the top of the can, the sides of the can, and the top of the water. Yeah, and it pushes all the product down to the bottom.

Right. Which is one reason you got to shake it up. Exactly. So you have a tube going down from the nozzle at the top of the can. Yeah, the valve system. All the way down to the bottom of the can, where the liquid is, right?

Yeah. And that valve has a seal that's being pushed up by a spring. So the head, the nozzle, when it's not being pushed, it's sealed tight. But when you push it down, a channel opens. It goes below the seal. And you now have the outside atmosphere, which is at a much

lower pressure than inside the can, opened up to the inside of the can at that much higher pressure. And it drives it up the tube, out the little tiny, tiny hole which atomizes it. And that's basically the simpler method of the aerosol can. Yeah, the air pushes the liquid down and then up the tube. Yeah.

Because it's like I want to get out too. Exactly. It expands. Done. I mean, that's pretty easy. Yeah. The war on drugs impacts everyone, whether or not you take drugs.

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The war on drugs is the excuse our government uses to get away with absolutely insane stuff. Stuff that'll piss you off. The property is guilty. Exactly. And it starts as guilty. It starts as guilty. The cops, are they just like looting?

Are they just like pillaging? They just have way better names for what they call, like what we would call a jackmove, or being robbed. They call civil acid for it. Be sure to listen to the war on drugs on the iHeart radio app, Apple Podcasts, or wherever you get your podcasts. How's that New Year's resolution coming along?

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That's right. We're two best buds who've been at it for more than five years now, and we want to see you achieve your money goals. And it's our goal to provide the information and encouragement you need to do it. We keep the show fresh by answering lists or questions, interviewing experts, and focusing on the relevant financial news

that you need to know about. Our show is chock full of the personal finance knowledge that you need with guidance three times a week. And we talk about debt payoff. If, let's say, you've had a particularly spend-thrift holiday season, we also talk about building up your savings, intelligent investing, and growing your income.

No matter where you are on your financial journey, How to Money's got your back. Millions of listeners have trusted us to help them achieve their financial goals. Ensure that your resolution turns into ongoing progress. Listen to How to Money on the iHeart radio app, Apple Podcasts, or wherever you get your podcasts. So the second way that this can happen,

and I didn't know this was the more common way, but it is these liquefied gas. So that is the propellant. You've still got the same product. And the product is sitting there at room temperature, just fine as a liquid, so they just pour that in. Then they seal it up. And then the same way with the other way,

they pump in this liquefied gas. And it mixes, though, this time, right? Or does it press it down? This is where I got a little confused. So a liquefied gas, you said, is a gas that goes into a liquid state under a certain amount of pressure, right? Yeah.

Okay, so under high pressure. Yeah. So it does mix, because it's all liquid in there once it gets in there. The whole thing turns liquid. And you keep that pressure up, so it doesn't have any room to expand, so it's just in there mixed together.

Exactly. And then when you press the nozzle down and you break the seal, as it were, the, you form a channel with the outside air and the inside air that change in pressure converts some of that propellant into gas. And it does the same thing as that standard can. The gas presses down, forces the liquid up.

But some of that propellant is still in liquid form mixed with the product. And as it goes out, it evaporates. Right. It turns into gas. And it also kind of, it turns that liquid product into a finer mist. Yeah, but what I don't get is that it actually boils

in the liquid gas system. It's like once you relieve that pressure, it starts to boil and that's what does it. That's what I was a little confused about. Yeah, I have a feeling that this is a different part of fluid dynamics. Okay. That it's not necessarily the boiling point,

although it could be. Because I don't think any average gas turns into a liquid under pressure. There's just certain kinds that do, I think. Okay. So I think, what's your question? Well, it's actually boiling in the liquid gas type of aerosol can.

At the very least, it's converting into a gaseous state because of the release of pressure. Okay. Right? All right, and why did the can sometimes get cold? Did you figure that out? No. Okay.

Boy, there's some people in chemistry lab right now that are just like, oh my God, you guys. I thought we had this one, man. I think we do. I could have done a tap dance doing this earlier. Now it's like, but wait, let me complicate it a little more. No, I think the message got through. In the case of paint, sometimes you need a little help

mixing these things together. So that's why a paint can, a spray paint can, will have the little metal ball bearing on the inside. Right, because you actually do wanna mix the propellant and the product together in a liquefied can, liquefied gas can. Yeah. Right?

Because it helps atomize it, as you said, and that's very pleasant. Exactly. And what about the rounded bottom of this spray can? You know why that's that way? I do. If it was flat, it's so pressurized, it could be a bad scene.

It could actually go the other way. And everyone knows if you studied architecture that a dome is more structurally sound than just a flat surface. So that's basically the same concept at play. So that's one reason it's to protect the integrity of the can. And the second one is, is so you can help get

all of the product out because if it was flat, it's like when you're down at the bottom of your soda cup with your straw, and you're making that terrible little noise and you're tilting the cup and trying to stick the straw on the little corner where it meets the edge. This does it for you. If it's a rounded bottom,

it just puts all the product there at the edge. And that's where the little tube is, and so you're all set. Nice. Yeah. And did you know there's about 19 billion steel and aluminum cans that include aerosols and other products that are recycled every year

and that's equal to enough to build 20 Golden Gate bridges? Really? Yeah. Wow. Isn't that amazing? So we mentioned there's a variety of different products that you can have that you're trying to get out of your can from foam to like whipped cream to bug spray,

stuff like that, hair spray. Although, does anyone still use aerosol hair spray? I think some people do. It's out there. Remember, do you remember the Bizarre Ways to Die episode, the deodorant boy, who used some aerosol deodorant that he died? I totally, man, that was a long time ago. Yeah.

So the way they accomplished this though with a different product is you can have a variety of consistencies and what they do is they just play with the ratio propellant to product maybe, maybe the chemical makeup of the propellant to product have to be just right. Maybe the pressure of the propellant has to be a little different depending on what kind of product you're working

with and then the size and shape of the valve system, like in the case of a fix-a-flat that you put in your tire, it's not the same as a spray can. It's not atomizing. It's got the tube hooked up and it's, if you've ever sprayed that stuff in your house, like the Philly Crack, like a whole can of it, it's amazing how much stuff is packed in there.

Yeah. Like when it gets out, you're just like, wow. It's like the clown car of the industrial engineering scene. Do you want to know a little bit about CFC's chlorofluorocarbons? Yeah, I didn't get a chance to look into this, but I'm glad you did. So prior to the late 20s, there was,

people were using ammonia in refrigerators and dying from ammonia leaks and it was just a bad scene. And so everybody said, well, we've got to figure out some sort of toxic, non-toxic chemical that we can use as a refrigerant. And a General Motors engineer of all people came up with what Dupont later turned into Freon. Right.

A chlorofluorocarbons, which supposedly was non-toxic. It basically changed everything. Yeah. It was much less harmful compared to ammonia. It allowed us to make cheaper refrigerators, car AC, AC window units, like all those things came from the advent of chlorofluorocarbons, right? Yeah.

And it was also very ubiquitous as a propellant in aerosol can sprays. Sure. Okay. Well, I think that's why everyone quit using Aquanet. Right, because everybody was going to spraying these things and they were going up in the atmosphere and everyone was like, look at them go, it's cool.

They're like, you know, inner non-toxic chemicals going up in the atmosphere. But we're all getting cancer. The problem is when a CFC enters the atmosphere and gets high enough and it's exposed to UV radiation, it breaks down and into its constituent components, one of which is chlorine. Chlorine wreaks havoc on the ozone layer.

One atom of chlorine can destroy about 100,000 ozone molecules. And we need those molecules. The ozone layer protects us from UVB rays from the sun, which are the kind that give you skin cancer and destroy crops. So in 1974, some scientists realized that CFCs were doing this thing in the ozone layer

and it's going to be big trouble. 74, huh? And then in the 80s, we figured out that there's a hole in the ozone layer over the Arctic. So a bunch of countries, I think 70 signed on to basically outlaw CFC production. In the 80s? Yeah, and then later on, another like 120,

I think signed another treaty. So it's very, very difficult to find CFCs these days, but they're still around. Are they? Yeah, they still use them in some nasal sprays. And they're also used in Halon, which is a fire extinguisher for airplanes. Did they not still use freon?

No, I don't believe so. Oh, okay. Yeah, it's basically like we did away with those. It's going to take a while to repair, but they found that the ozone layer is no longer growing. The hole in the ozone layer is no longer growing. It's just holding steady and hopefully patching itself back up.

They just forced people to go out and be innovative and find different ways to do these things. Exactly, and if you compare your aerosol can, propellant today to one that had CFCs before, you're not going to notice the least bit difference. So that can of aquanet that looks exactly the same as it did in 1957 is no longer dangerous. Not to the ozone layer.

Right. It is to spiders though, if you have a lighter. Yeah, don't ever do that, kids. No. That's it for aerosol cans unless you have like another 10 minutes on it. No, that's all I got. I mean, cool.

What else is there? I genuinely looked and there is nothing else. Yeah, go out and do some graffiti. That's what I say. Artful graffiti though. Don't go around tagging stuff. You should probably practice at home first. I hate that just stupid.

Yeah. Like educate yourself on different types of nozzles, like practice, don't be a punk. Agreed. Be an artist. If you want to learn more about aerosols, or at the very least you want to see the article where we told you everything there is to know about aerosols,

you can type that word, A-E-R-O-S-O-L-S into the search bar at HowStuffWorks.com. And that will bring it up. And I said search bar, which means it's time for a message break. Stuff you should know. The war on drugs impacts everyone, whether or not you take drugs. America's public enemy number one is drug abuse.

This podcast is going to show you the truth behind the war on drugs. They told me that I would be charged for conspiracy to distribute 2,200 pounds of marijuana. Yeah, and they can do that without any drugs on the table. Without any drugs, of course, yes, they can do that. And I'm the prime example of that. The war on drugs is the excuse our government uses

to get away with absolutely insane stuff. Stuff that'll piss you off. The property is guilty, exactly. And it starts as guilty. It starts as guilty. Cops, are they just like looting? Are they just like pillaging? They just have way better names for what they call,

like what we would call a jackmove or being robbed. They call civil acid for it. Be sure to listen to the war on drugs on the iHeart radio app, Apple Podcast, or wherever you get your podcasts. How's that New Year's resolution coming along? You know, the one you made about paying off your pesky credit card debt

and finally starting to save a retirement. Well, you're not alone if you haven't made progress yet. Roughly four in five New Year's resolutions fail within the first month or two. But that doesn't have to be the case for you and your goals, our podcast, How to Money can help. That's right, we're two best buds who've been at it for more than five years now,

and we want to see you achieve your money goals. And it's our goal to provide the information and encouragement you need to do it. We keep the show fresh by answering list of questions, interviewing experts, and focusing on the relevant financial news that you need to know about. Our show is chock full of the personal

finance knowledge that you need with guidance three times a week. And we talk about debt payoff. If, let's say you've had a particularly spend-thrift holiday season, we also talk about building up your savings, intelligent investing, and growing your income. No matter where you are on your financial journey,

How to Money's got your back. Millions of listeners have trusted us to help them achieve their financial goals. Ensure that your resolution turns into ongoing progress. Listen to How to Money on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts. And now it's time for Listener Mail. I thought you might say that.

OK, Josh, Listener Mail time. I'm going to call this Police Sketch. I witness stuff. Good stuff. This is from Terry Bennett. Hey, guys. Listen to the Police Sketch episode and wanted to share my story.

It was robbed when I was a teller of a bank in 1977. And at that time, bank robbery was a federal crime, probably still is. I was immediately taken into the back room of the vault and the FBI was called in. When they arrived, a sketch artist brought a large binder, not full of women, but full of pictures, faces, and eyes, and noses, and mouths, et cetera.

Transparencies of face shapes were the base, and the rest of the face was built on the base, one eye and nose at a time. I was not allowed to talk to anyone, including the staff of my bank, until I talked to the FBI. I was instructed to write everything I could remember about the robber and the robbery before talking to anybody else.

In those days, of course, we did not have digital cameras, and the film had to be sent out for processing. I love it in those days. I mean, like, it was the same, like, seven or eight years ago. Right, yeah. Actually, when did digital come around? The early 2000s, it seems like it became... I guess it's more than seven or eight years now.

I know. We're getting old, man. So the pictures took a couple of days to get back, and my composite drawing was posted in the paper, and my robber was actually caught a couple of days afterward at a methadone clinic in town. When the film was developed, the side-by-side pictures were incredibly close, so she did a pretty good job, sounds like.

Nice. By the way, he was caught using my composite and not the true picture. Huh. That's pretty cool. Yeah, it's very cool. We were trained to observe all these details and also to watch for the six-foot mark as the robber left the building,

like you talked about, they called it stores. Yeah. Guess they have those at banks. Luckily, even though I was only 20 years old, the training had taken a hold. It gave me great resources to catch this guy. To this day, I always observe shady or odd things

in everyday life, including license plates, like you talked about. By the way, my robber had robbed eight other banks up and down the coast in California, and I got to be a hero for a minute. Wow. And that is Terry Bennett, and that's a cool story. Yeah, that's very cool, Terry.

Thanks for sharing. I bet she just eyeballs everybody. Right, yeah. She's saying that weird lady now. She just takes out methadone clinics. Yeah. What are you doing? Just getting my methadone.

If you want to give us a story, we love our stories, you can tweet a very, very, very short story to us at S-Y-S-K Podcast, that's our Twitter handle. You can post one on facebook.com slash stuff you should know. You can send it in an email to stuffpodcast.discovery.com, and you can't really tell us a story, but you can hang out with us at our home on the web, stuffyoushouldknow.com.

For more on this and thousands of other topics, visit HowStuffWorks.com. This episode of Stuff You Should Know was brought to you by Audible.com. The war on drugs is the excuse our government uses to get away with absolutely insane stuff. Stuff that'll piss you off. Cops, are they just, like, looting?

Are they just, like, pillaging? They just have way better names for what they call, like, what we would call a jackmove, or being robbed. They call civil acid for it. Be sure to listen to the War on Drugs on the iHeart Radio app, Apple Podcast, or wherever you get your podcasts. Hola, qué tal, mi gente.

It's Chiquis from Chiquis and Chill Podcast. Welcome to the show. I talk about anything and everything. I did have a miscarriage when I was 19 years old. And that's why I'm a firm believer and an advocate of therapy and counseling. The person that you saw on stage, the person that you saw in interviews,

that was my mother, offstage. Apobanyame every Monday on my podcast, Chiquis and Chill, available on the iHeart Radio app, Apple Podcast, or wherever you get your podcasts.