How do fireworks work? From the basics to fully choreographed displays, we take a look at the tech of making stuff go boom.
Welcome to tech Stuff, a production from I Heart Radio. Hey there, and welcome to tech Stuff. I'm your host, Jonathan Strickland. I'm an executive producer with I Heart Radio, and how the tech are you? You know, here in the United States, it's the fourth of July. Technically it's it's fourth of July other places too, but here in the United States that date has historical significance and as such, we observe it as a holiday, which means I am not at work today, and Tari is not at work today, and I don't believe in making people work on holidays, and so we are going to listen to a classic episode of text Stuff. This is a part one of a two partern so tomorrow we'll listen to part two. Because there's just something in me where I can't just let it go, where I just play part one and never play part two. Here we go. This episode originally published on July twenty third, two thousand and fourteen, and it is called tech Stuff. Lights Some Fireworks Enjoy. Here's something I wondered as we were watching the traditional Independence Day festivities. What kind of tech goes into a professional fireworks display? What do they use to sink up the fireworks with music is their fancy tech that goes into the creation of fireworks. Most of the ones I saw tonight were the standard fare starbursts that could change their colors. They burned, uh, though some twinkled like little Christmas lights, flashing on and off in a way I wouldn't expect from just a chemical burn. I also remember years ago seeing some explode into a smiley face, though I haven't seen as many of those recently. I also wondered if there's anything that makes them safer, though I'm not sure how safe you could ever make something that's designed to explode if it hasn't been done already. It might be cool to hear about how fireworks work. And Cyber Knight, we are totally going to meet your expectations. We are going to exceed them actually, because they at there's a lot of science. There is. There's much, many much sciences. In fact, I would say more science than tech when you get down to it. However, it's a technology of chemistry. Yeah, it is applied chemistry, so there is. And we have demonstrated on the show previously that we like fire Yeah. We did a full episode. By the way, sorry, we didn't talk about compression fire starters. I had it in my notes, did not fill it out, and then we were taken to task for it. Rightfully, So I would say, but we're gonna we're gonna be very thorough as it turns out with fireworks, because while I was thinking about it, you know, just covering the basics, the more I got into the chemistry, the more exciting it was, the more interesting it was, and the more I was like, well, I'm in for opinion for a pound. If the government's going to see how I'm looking about, you know, how to make gunpowder, might as well go all in. So we're going to talk all about it. Definitely one of those that were like, okay, what interesting watch lists are we on? At least three or four more? So we should probably define what a firework is is for just just the purposes of framing the discussion, right, sure, Well, you know, at its base, I suppose it's something that explodes for fun. Yes, that's pretty much it. A firework is something that is explosive or combustible, and it's meant for display purposes, to to create an impressive light display or exactly. Yeah, you could get a firecracker, which is really meant to make a lot of noise, or your you might get a Roman candle, which doesn't make a lot of noise, but it is very impressive light show. Uh. And of course then there's all the stuff that also falls into the fireworks category, things like sparklers, that kind of stuff. We're mostly gonna be focusing on your traditional fireworks, the stuff that you would go and look up into the sky and see that plays that are launched from something into the air exactly, So your your common basic ingredients and fireworks are well. It's black powder, also known as gunpowder. You know, pretty pretty simple, relatively simple. Uh. It's traditionally made from sulfur, charcoal, and potassium nitrate, which back in ye old days was called saltpeter. Yeah. And back in the old days, he mostly got it from India, at least if you were in the Western hemisphere, you got it from India. Uh. In fact, I read an interesting article published in eighteen sixty one by the New York Times about the various powder mills, which we'll talk about a little bit, uh in the United States, and essentially it was running down how the South didn't have enough powder mills for this Civil War thing to be a big deal. As it turns out, four more years later, they probably felt like that was maybe a little premature. I think, yeah, that that turned out to be less correct than they had hoped. It was a certainly, you know, I think it was an optimistic take on what ended up being a very trying time in the U. S. History. But we're going to focus on the fireworks. So speaking of history, looking at the history of fireworks, this is stuff of legend. As it turns out, Oh, certainly, because I mean, guess what neither of us were around two to three thousand years ago to observe and we don't have a real way back machine. Yeah, I'm really sorry, guys, we have been lying to you. It's just a special effect. It's a really special effect. It is. It is very special. Unfortunately, if someone has not actually documented it in a way that is verifiable, we cannot, in fact go back and say exactly what happened. But we can tell you what the legends are. Yes, there's a legend that over two thousand years ago in China, a chef, a chef was mixing together some charcoal, some sulfur, and some saltpeter, and those were all ingredients that were found in field kitchens. Okay, so uh yeah, apparently just accidentally happened to measure these in the or or mix these in the right amounts, because it's not like you have equal parts of each ingredient. It's actually more precise than that. Aren't going to talk about that because I don't want you guys making gunpowder, so don't try that at home. But this chef happened upon this recipe, Yeah, discovered that if you compress it, like if you put it into a container of some sort, and then if it were too I don't know, come into contact with any kind of flame, it blows up. I don't know if that chefs survived this discovery, because I don't even know if the chef's existed, So it's all up in the air really literally possibly depending upon where the gunpowder was. Now, if you look up the history of fireworks online, like if you were to actually go and put into your favorite search engine history of fireworks, you're going to find a particular story told repeatedly throughout numerous links, most of which go to like fireworks manufacturers and as like many other research topics, on the Internet. They all tell basically the same story and basically the same wording without any particular reference anything real. Yeah, there's no citation, right, yeah, so that so what the legend is is that there was a monk in China named le Chian who lived around quote a thousand years ago. That is always the way it's put, by the way, around a thousand years ago. It's never given a date. It just as around a thousand years ago. And so depending upon when this was written, you know, and anyway, so much so many different sources use the exact wording. I expect they all took their information from either the same source or they're just borrowing it from each other. It's just this big circle of people borrowing the same stuff. But the best scholarly source I could find simply said that the first firecracker was made sometime around eleventh century Common era in China, so eleventh century a d if you prefer, in China. And this was the time when Chinese alchemists were searching for something called the elixir of life. And along the way, while trying to find this elixir of life, they they mixed a bunch of different kinds of stuff together and found lots of interesting things, not the elixir life, but as it turns out, they found out about gunpowder. Just kind of like an a lixer of death. When you think about it, it can be certainly with the with the incorrect application. So the first firecracker was probably a parchment tube loosely filled with this mixture of saltpeter, sulfur and willow charcoal. Willow charcoal, by the way, one of the more popular forms. As it turns out, you want to use softer woods to create the charcoal because the harder woulds tend to create too much ash. I learned that while I was doing all this research. Now, once these things were invented, they started to spread throughout the world gradually, usually through trade. Uh. Sometime between twelve thirty five and twelve nine, d Roger Bacon began to experiment with an early form of black powder. This was again stuff that had probably been brought to the Western world through trade, yeah, mostly through Arabic traders. Most likely the story goes that Marco Polo brought some over, but it's much more likely that it was Arabic traders well before Marco Polo's journeys. But at any rate Bacon's work would lead to the development of what we know as gunpowder today. Yes, he would. He would sort of refine this mixture, finding the right proportions of mixing these ingredients together to get something that would work very well if you wanted to, uh, you know, launch something at somebody, like say a cannonball. Sure, because if you mix all of these things together, you get a good bright flash, and if you compress them beforehand, you get a big boom as well. Yep, yep. Otherwise, like if you've ever seen those videos of or films of people taking the old timey photographs with the flash powder, where it just it just lights up, and that was how they created a flash since they didn't have the capacitors to make up a flashing light bulb. That's what gunpowder does. If it's just out in the open. You've probably seen this. It's you know, it's also really popular in like cartoons and stuff. You see the long trail of gunpowder and the exactly so that really is how it just burns really really quickly. Now, the gunpowder industry and fireworks industry are very closely linked together. Improvements in developing gunpowder and the methodology for producing it were ported over to work in fireworks as well, and early fireworks displays were developed in China and India for religious festivals. Uh. There aren't really written accounts of how these fireworks spread throughout the world. But again we think that Arabic traders probably brought this stuff over into Europe and the Europeans said, Wow, that's amazing, that's awesome, let's bloss stuff up here too. Yeah. And in fact, for a long time they were importing this stuff from the East, and in fact would even higher experts from the East to come and do the displays in in Europe. It would only be in the late Middle Ages early Renaissance when you started seeing Europeans try and take on this responsibility themselves. Uh. Now, by the Italian Renaissance, fireworks creators began to experiment with adding extra ingredients to mixtures to use different colors of light, so for example, adding copper to create blue light. We'll talk more about adding color to fireworks a bit later. So the thing is, if you want to learn more about what the displays back in the Middle Ages were like, there are only a few accounts. A lot of them though, come from England, because it turns out the English were bananas over this stuff. The Italians and Germans were working really hard on improving fireworks technology, and the English were enjoying the heck out of it. We'll be back with more in just a moment. So one of the accounts says that during the wedding of Henry the Seventh also known as Henry Tudor and Elizabeth of York in four six, there were fireworks displays. Others talk more about Elizabeth's coronation, so there's a little bit of a argument there. The same is true for Henry the eighth wedding uh and Bleyn, which was a wife number two. I think I think she had a good head on her shoulders. Uh not for long. Spoiler art James Anthony Froud wrote that there were quote wild men casting fire and making a hideous noise end quote, which I think is a fantastic description of fireworks. When I was a kid, I hated them because I didn't like loud noise, and even just seeing the fireworks burst in the sky made me made my anxiety levels go up because I knew a loud noise was coming right right. I remember having one year where I was really upset by them, like I had loved them and then suddenly was like that's loud and I'm against it. Yeah, I've come back around now, but for a long time I was. I was certainly the person who was like, I don't want to be here when the fireworks start UNA for the record, Yeah, yeah, most dogs I've encountered shared my feeling. I think I finally evolved beyond dog stage. So Henry the eighth and Ann BERLEYN had a daughter, Elizabeth, Yeah, somewhat famous. Yes, it became Queen of England and uh sat on her thorn for many years throne throne. Sorry, it was just misreading my notes, but no, Elizabeth obviously one of the most influential um monarchs of all time. Really yeah, and she she loved the sparkles. She did she she she created a position for its Firemaster of England. Um, it would be I think it was after in the ruling of James the First when that position came along with the knighthood. At any rate, you had people who suddenly really wanted to pursue the craft, to become the best at it, in order to land this cushy job of being the fire Master of England, because you would imagine that comes with some sweet you know, bonuses like money. Yeah, and so a lot of people were trying new and different things to kind of impress the queen. Yeah. Yeah. According to some accounts, one of the things you might expect to see at a true, really outrageous display would be a dragon with paper mache scales that was loaded up with fireworks so that it would breathe fire. It would appear to be breathing fire, and sometimes they would have more than one, and then you would have dragon fights, yes, and then maybe one of the women's up catching on fire and the other one is slightly less on fire, and so that's the one that wins. Um. But they would battle one another. And so you read about this kind of stuff, you're like, wow, these these had to be pretty spectacular. And then you also think, remember they had no automated way this. There was probably some poor jerk who had a match stick or some form of torture something that was lighting this stuff manually and then trying to get the heck away from it before he burnt up. Yeah, or possibly a couple of guys on the ground like with sticks holding these things up. I'm a little bit terrified about the entire concept, but but yeah, no, they were very impressive. Shakespeare even wrote wrote about them in some of his plays, Right, Romeo and juliet There is a quote that says, these violent delight have violet ends, and in their triumph die like fire and powder, which as they kiss consume. Now, in that case, of course, he's referring to the lover's Romeo and Juliette, and the passion they have for one another, and he's likening it to a fireworks display, which you know, has been a pretty powerful image that has been repeated at nauseum ever since. The whole thing where the two lovers kiss and then you see the fireworks going off in the background very much. It's interesting that it seems to have originated with Shakespeare, as many so many things have. Also, fireworks were deemed to be an illegal possession for regular citizens right around six five. Uh, yeah, that that's about when a certain persona now publicly known because of a certain movies comic book. Yes, guy Fox got into some trouble with the gunpowder plot. Yes, he was part of a conspiracy to blow up the houses of Parliament by storing something like thirty something casks of gunpowder underneath. They were going to tunnel underneath the Houses of Parliament that stuff in there and then light it and blow it up. And the conspirators were caught before they could execute their plan. And Guy Fox himself, who was not necessarily the ringleader, he was one of the members Um, was really made an example of in some of the most horrifying ways you can imagine. Now, granted he was playing on committing a terrible act, but they did a really terrible act him and drawn quartered And of course they had Guy Fox Day for you know, the early Guy Fox days involved lots of burning of Guy Fox and effigy Um. And then there's a whole story there that's amazing, but stuff he missed in history class would really be the best place to cover that. And I'm sure they have actually mean, I feel like it's likely. Yeah, these these days we have the charming anonymous masks based off exactly. So at that point it was made illegal for the common citizen to possess fireworks. The only people who are allowed were specifically given that that responsibility by the crown. So that's kind of the early early history. But let's talk about what's actually going on inside of firework. What is what is making it work? Well, this is mostly chemistry, but let's let's talk about black powder, since that is that is the basic what is going on here. So we talked about sulfur, charcoal, and saltpeter or potassium nitrate. Uh, you might wonder what are these things actually doing within gunpowders. So sulfur and charcoal are acting as fuel, right, and the potassium nitrate is acting as an oxidizer. So oxidizers in this sense are the chemicals that fuel requires in order to burn. If you remember the great triangle of what is required to make fire, you have to have fuel, you have to have oxygen, and you have to have heat. Those are the three things that together will allow you to have fire. And if you're lacking any of those, you're not going to get it. If you have just oxygen and fal and but not heat, it's not gonna happen. Same thing with just oxygen and fire. You've got to have some fuel there. So oxydizers are chemicals that are really good at getting oxygen into the mix. Yes, And in fact, potassium nitrate is incredibly good at this. So let's look at these ingredients each on their own. If you look at just charcoal, which is essentially carbon and you want to try and burn it, if you were to light a match and just hold it to charcoal, it doesn't really ignite very well, yeah, kind of. It kind of smolders and smokes, and and if you get it hot enough, like it will start to burn. Certainly they'll start to glow, blow, doesn't. You don't get a lot of flame out of it. You've probably done this at home, perhaps on a charcoal grill, or when you have burned a log down to the coals. Yeah, you've got those those coals are that's charcoal that's just glowing because of the heat that's coming through. We'll talk about the actual mechanism of glowing a little bit later too. So again, you don't get a lot of ignition, not not in a lot of flame. It's certainly not explosive ignition yet, probably unless you've done something very strange, right, unless unless your charcoal has got some other funky ingredients in it, or I guess you've compressed it a lot. Maybe I'm yeah, that would be incredible. Eventually you would get a diamond. So, but sulfur it burns at a lower temperature than charcoal does that carbon does. It ignites more easily, but not really at room temperature. So if you had a little crucible, let's say, a little ceramic crucible filled with some some sulfur, and you put a match to it, it wouldn't really light up. But again, if you were to heat it, it will start to melt, and then it will burn if exposed to even higher temperatures, and that gives off sulfur dioxide, which, by the way, not good to breathe in. It could irritate your lung. One of the many reasons why you shouldn't melt sulfur at home. Yeah. Yeah, these these things like charcoal that's fairly fairly benign as things go. Sulfur a little bit less so, uh, potassium nitrate less so than either of the other two. Yeah, this is what increases that rate of combustion significantly when it's added to a mixture of carbon and sulfur, again in the correct amounts. So when it's mixed properly, that combination willing nite and burn really really quickly. Um. And it is it is the of course the traditional oxidizer in this combination of stuff that goes into black powder, but lots of other things can be used, for example, potassium chlorate, potassium perchlorate, or barium nitrate and UH. As of twenty eleven, organizations from like Walt Disney Company to the U. S. Department of Defense have started looking at green alternatives to all of these oxidizers. UH and I say green, and you go, like, what you're making stuff explode? How green does it need to be? But the thing is is that um okay. So it turns out the dangerous chemicals can present health and environmental hazards. UM and potassium nitrate specifically is a really common ingredient in herbsides, Potassium chlorate is a hearsh ingredient in disinfectants. Potassium perchlorate can disrupt the production of hormones and the thyroid and harmon born babies, and a barium nitrate can interfere with heart and breathing functions. So none of that is good fun times and and so a lot of research has been put in recent years into trying to figure out better ways of burning stuff, yet that isn't releasing these chemicals into the environment and showering them over crowds of fawning onlookers, or you know, into your water supply, or for example, potassium chlorate is a great example. Potassium chlorate is this stuff a great example of a bad, bad ingredients as opposed to one that's green. Potassium chlorate ends up creating a more explosive burn than say, potassium nitrate does. Potassium nitrates already pretty impressive, but if you ever watch someone create potassium chlorate a mixture of sulfur, charcoal and potassium chlorate in the right amounts and then light it, it lights even, It burns even faster than the regular black powder mixture, and so it's often used in something called a burst charge, which we'll talk about later. But like you said, it leaves some pretty nasty stuff behind chlorate. If you look at that word chlorate, you realize that chlorine is one of those things that's involved in this, and that's one of the byproducts as you get this chlorine released as as one of the the remnants after the chemical reaction that happens when you ignite this stuff. Chlorine is not good stuff, folks. You don't don't want just pure chlorine all over the place it's it's toxic. So you know, that's one of those things where uh a lot more research needs to be done in order to make the stuff really safe. Right now, two things, sodium parietate and potassium parietate are starting to move into use as substitutes, more clean substitute for the traditional one, because the trick is that you have to find something that's going to facilitate this rapid burning. If you don't have that, then obviously you can't do the fireworks at least not the way we're accustomed to. Um. So we'll we'll, you know, hope that that kind of stuff gets further distributed throughout the entire industry so that we have a less uh you know, negative impact on the environment and potentially on on the viewers of fireworks displays or just the people who happen to live around those areas. Oh yeah, this this also goes into I mean, the Department of Defense wasn't involved in that because of the fireworks displays necessarily, so much as this is useful also for anything else that you're using gunpowder for for the Department of Defense as many things, and you know, trying to protect the lives of our munitions workers and also our our soldiers and troops and everyone else. Absolutely, I interrupt this episode of tech stuff to let you know there's going to be some messages followed by some more tech stuff. So how is it made? Don't try this at home, yes, do not. This is one of those things that if you are if you're part of a lab and the lab has the facilities to do it, and you can make it in small amounts. It's a very interesting process. But this is not something for you to ever try on your own because if you got the mixture either just right or just wrong, bad things can happen. But generally speaking, here's what the processes, and I'm not again going to explain the specific amounts. First, you would have to reduce each ingredient to find grains of powder, and you would want to do this separately. Right this, You don't mix them together first, So you get your charcoal and you mash it up so you've got charcoal powder. You get your sulfur. You make sure you you pound out any any clumps so that you just get a fine powder. Same thing with your saltpeter. You want to make sure all of that stuff is as fine as you possibly can make it. Then you mix those ingredients together with a little water or some other liquid. For example, and I'm not making this up, one of the liquids I saw was stale urine. Stale urine stale urine specifically stale Yes, I am not joking, because it allows for a more consistent burn. Um. Yeah, all right, So anyway, you mix it in with this liquid to help these different ingredients bind together, Usually you have some sort of binding agent. What's some something that's going to help them stick together in the right in the right amounts. Saltpeter, as it turns out, was really soluble and it will fill in all those nice little spaces, and charcoal pretty easily. Charcoal has a lot of surface areas, so it's it's a good mix. Then you let the mixture dries, becomes kind of like a cake like mass. It's solidifying like a hard biscuit. Yeah, it's like a red velvet cake, right, Yeah, so it's it's much more dense also much more likely to explode than your traditional red velvet uses. You then crush this dry matt mass with something that will totally not cause sparks. Please, Yeah, you don't use any nothing that's gonna potentially create spark, so usually it's ceramic or non sparking metals or something along those lines of stone, just regular stone, not like Flynn steel, would be a terrible idea to turn it into a powder. Um. This is one of the reasons why it's challenging to make this stuff in huge amounts, particularly for someone who doesn't have like a powder mill at their disposal. They the accounts I read were especially for people who are like, uh, military recreationist people, people who create, uh they recreate like the famous battles, and they want to have black powder muskets. They're not firing musket balls, but they want to be able to have that big loud bang smoke um they talk about making us say, it's a little hard if you want to make more than say, ten pounds of the stuff at a time, and like, you know, keeping in mind that ten pounds of gunpowder, especially if it's in a compact container, it could be incredibly dangerous. I just had a very mild panic attack thinking about any of the people that I personally know who dress up in costumes and run around the woods firing fake guns at each They're having ten pounds of gunpowder at your disposal. Yeah, it's uh, it certainly is one of those things where you do need to know the best practices to safely handle this stuff because it really is incredibly dangerous. But at that point in this process, you're done. You've got your gunpowder. If you do want to make large quantities. How did those powder mills work that you were mentioning earlier? So, yeah, you usually you would have some sort of of bowl like surface, and then you'd have a grinding wheel that would be powered either by horsepower, manpower, or water wheel, that kind of thing. So it's a mill, you know, the kind of mill that you would see for any other sort of thing, grinding grain, for example. And what you would do is you would you would mix all these ingredients together and then you would put that in the mill for it to grind up into the proper um fine powder that you would need to use as black powder. Again, you would have to make sure that all the equipment you had was not likely to cause a spark alright, wood or stone or something non spark making. Yeah, it's it's hard, non sparkworthy. It's kind of hard to to put it into words. Properly it is incombustible. Yes, that's good. One other interesting feature that a lot of these powder mills had was that at least one wall, sometimes more than one, was specifically built weaker than the other walls. The other walls would support more of the structure's weight. H so that if everything in the factory exploded, it would be easier for people to get out well, or easier for firefighters to get in. Uh yeah, because I mean if you are caught inside that building when there's an explosion, there's probably parts of you got out. Um yeah, it's it was meant so that it could open up an easy pathway for any uh, reactionary measures measures, whether that's putting out fires or you know, dealing with the aftermath. I mean, you didn't necessarily have people inside these things all the time while they're grinding with any but it was meant as this way. It's like, let's say, if you have it as a water wheel, you know it means you're near a source of water, running water, you might have the wall that is closest to the running water blowout, So that way, if there is a fire, you can you've got the water right there, so you can start a bucket brigade type thing. Now that's why I kind of had a face upall moment thinking about that one. But now that you mentioned it, really that's I sort of want all of my buildings to be structurally weaker on one side. I mean, nothing else that I could just man right out of anything that would be fair. Yeah, there are so many times where I just think that I need to have the Jonathan shaped dust cloud and then the wall like the Jonathan shaped hole in the wall where I've made my escape. So these days, we don't have so many water wheels kicking around in large factory facilities. We do have some machine versions that will do the crushing, but again it's really tricky because you have to make sure that that machinery is not going to have any kind of sparking element to it. So, in other word, the motors can't be sparking, not just the rollers or whatever. So you have to make sure that the materials you're using the surface and the rollers that are doing the crushing are not going to create any sparks, and furthermore, that they're going to be cool enough to not risk igniting it. Yeah, yeah, exactly. So it's It's one of those things that really took a lot of of effort to get it right so that it could be created safely, or at least as safely as possible. Accidents still happen. I mean, you've probably heard of accidents, whether they were in facilities that were processing black powder or a fireworks warehouse, These things do happen. So it really drives home the fact that you've got to treat it with respect. Sure, sure, Okay, So once you've got your black powder, how do you assemble the fireworks themselves? Okay, so basically, and we'll talk more about this in in our part two about fireworks, but basically what you need to do is do it by hand because automated versions again tend to have equipment that could create a spark. And so you've most fireworks are are handmade, hand packed. So if you if you were to take a typical firework, like a big one one that's used in a professional display, these things tend to weigh several pounds, They can be in lots of different shapes. It all depends upon the effect you want. We'll talk about that in the next episode two. But if you were to cut it in half, you would see that you would have a core of this black powder, whether it was made with potassium nitrate or potassium chlorate or some other oxidizer involved, but the black powder would be at the core, and you would have these other little elements inside the firework that are meant to be projected outward after the core explode, all right, probably suspended in clay or something staple like that, right right, And then you would also have another at the base of your projectile. Uh, if you have in fact a two stage firework. We'll talk about the different options in the next episode. But in the base of your firework, you would also have a lift charge which would be ignited another little gunpowder puck. Yeah, so you would have that at the base of it, and that's what would provide it the energy to lift out of the mortar. The basically the tube you have to fire it off into the sky. So it's it's really a two chamber at least a minimum of two chamber approaches if you're using the traditional method of launching, although the mouse House has come up with a totally different way of launching fireworks that doesn't require that separate blast chamber. The lift chamber and that was part one of our two part episodes on fireworks. We will have part two tomorrow. Hope you enjoyed it. If you have suggestions for future episodes of tech Stuff, you can let me know on on Twitter the handle that we use as tech Stuff hs W, or you can download the I Heart Radio app, which is free to use. You can navigate over to the tech Stuff podcast page and use little microphone icon to leave a voice message up to thirty seconds in length let me know what you would like to cover and again we'll have part two tomorrow and I'll talk to you again really soon. Y text Stuff is an I heart Radio production. 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