Speaker 1: Welcome to text Uff, a production from my Heart Radio.
Speaker 1: Hey there, and welcome to text Stuff. I'm your host,
Speaker 1: John than Strickland. I'm an executive producer with I Heart
Speaker 1: Radio and I love all things tech and tech stuff.
Speaker 1: Listener Nick contacted me on Twitter and asked if I
Speaker 1: might do an episode to talk about the different kinds
Speaker 1: of steel, in the different grades of steel, and what
Speaker 1: makes one different from the next. Now. I have talked
Speaker 1: about steel a little bit in previous episodes, but it
Speaker 1: was always in relation to some other topic. For example,
Speaker 1: I did a couple of episodes with my friend Ariel
Speaker 1: about swords, and that included some stuff on steel. But
Speaker 1: I really want to dedicate a couple of episodes to
Speaker 1: this metal and why we have so many different classifications
Speaker 1: of it and what this classifications actually mean. But first
Speaker 1: let's get to some definitions and history. In fact, that's
Speaker 1: what this episode is going to be about, is sort
Speaker 1: of the history of steel making in general, because it's
Speaker 1: complicated stuff. And in the next episode will conclude with
Speaker 1: the history part and move on to the different types
Speaker 1: of steel. Now, if you take a look at the
Speaker 1: periodic table of elements, you'll notice that steel is not
Speaker 1: on it. And that's because steel isn't an element, it's
Speaker 1: an alloy, and alloy is a metal created from the
Speaker 1: combination of at least two metallic elements. And technically steel
Speaker 1: is an alloy of iron and carbon. But here's where
Speaker 1: it gets really confusing. All the iron we work with,
Speaker 1: the iron that's in our stuff like iron nails and stuff,
Speaker 1: all of that is really an alloy of iron and carbon.
Speaker 1: So this means that these episodes are really going to
Speaker 1: be not just about steel, but iron and how we
Speaker 1: learned how to work with iron. Now you might wonder
Speaker 1: why you'd bother making an alloy in the first place.
Speaker 1: Why would you not just use pure iron? Wouldn't that
Speaker 1: be easier? Well, it's because alloys can have different, more
Speaker 1: beneficial properties than the individual elements that combine together to
Speaker 1: make that alloy. So, in general, the reason we make
Speaker 1: alloys at all is to create materials that are stronger
Speaker 1: or lighter, or more resistant to corrosion or some other
Speaker 1: positive quality or combination thereof, compared to the metals we
Speaker 1: use to create the alloy. In the first place. Steel
Speaker 1: is superior to iron in many ways, which we will
Speaker 1: get into. But to really understand the development of steel,
Speaker 1: we have to take a closer look at the history
Speaker 1: of meta allergy in general. So for thousands of years,
Speaker 1: humanity relied primarily upon stone as a material for tools
Speaker 1: and weapons. And we have a name for this age,
Speaker 1: the flint stones. No way, I'm sorry, I just meant
Speaker 1: the Stone Age. But we can further divide the Stone
Speaker 1: Age into the Paleolithic or Old Stone Age, you know
Speaker 1: when everyone was listening to that, you know, real crappy music,
Speaker 1: and Neolithic or New Stone Age, which is what all
Speaker 1: the kids were listening to. Stone is plentiful. It's hard stuff, right,
Speaker 1: It's durable. Depending upon the type of stone, you could
Speaker 1: fashion it into sharp edges, and you could polish it up.
Speaker 1: You could make stuff like axes and spears, and so
Speaker 1: the ancestors of humans were using stone tools as far
Speaker 1: back as three million years ago, not earlier. I mentioned
Speaker 1: for thousands of years. But that wasn't to d emphasize
Speaker 1: how long we relied on stone, but rather just as
Speaker 1: a nod to how tricky it is to apply the
Speaker 1: word humans, because we're talking about you know, ancestors of
Speaker 1: humans as well. While stone could get the job done,
Speaker 1: it wasn't necessarily the best material for most jobs. It
Speaker 1: was brittle and heavy, and you could find yourself with
Speaker 1: a tool that had edges that were not as sharp
Speaker 1: after a few uses, or one that would break in
Speaker 1: a relatively short amount of time. Also, when we talk
Speaker 1: about stuff like the Stone Age and the Bronze Age
Speaker 1: and the Iron Age, we have to remember that these
Speaker 1: terms describe very broad eras that didn't actually have a
Speaker 1: definitive beginning and end. Some regions moved towards metallurgy much
Speaker 1: earlier than others, sometimes by as much as two thousand years.
Speaker 1: So I just don't want any of you thinking that,
Speaker 1: you know, a person went to bed on a Wednesday
Speaker 1: night when it was the Stone Age, and then they
Speaker 1: woke up Thursday morning and it was suddenly the Bronze Age.
Speaker 1: It's a little more subtle than that. Generally speaking, we
Speaker 1: think of the Bronze Age as beginning around three thousand
Speaker 1: b c E, and we think of it as ending
Speaker 1: as well. That depends on where you lived. If you
Speaker 1: lived in Mesopotamia, it ended sometime around twelve hundred b C.
Speaker 1: But if you were in Northern Europe you had to
Speaker 1: wait a little longer. It was closer to six hundred
Speaker 1: b c. E. Generally, the onset of the Bronze Age
Speaker 1: was brought about by trade, so the knowledge of how
Speaker 1: to produce bronze spread outward from the Mesopotamian area for
Speaker 1: the most part, so cultures first began to learn how
Speaker 1: to work with copper, and at first copper was fairly scarce.
Speaker 1: It just wasn't as readily available as different types of stone.
Speaker 1: But ancient people's developed mining and metallergy and created all
Speaker 1: sorts of stuff out of copper. But copper is not
Speaker 1: that great for tools. It's not terribly durable, it doesn't
Speaker 1: hold an edge very well. But by adding some tin
Speaker 1: to the copper t I N tin, mellergists could create
Speaker 1: a much stronger alloy bronze. This material made much better
Speaker 1: tools and weapons. Iron is even stronger, but the high
Speaker 1: melting point of iron meant that the tools humans had
Speaker 1: for me allergy weren't sufficient to make iron. The pods
Speaker 1: used to melt copper and tin couldn't withstand the temperatures
Speaker 1: you would need in order to smelt iron from iron.
Speaker 1: Ore the word smelt means to extract metal from ore,
Speaker 1: and or is a solid rock or sediment that contains
Speaker 1: one or more metals or minerals in it, So smelting
Speaker 1: is really about separating the metal from all the other
Speaker 1: stuff that's in that rock so that you can work
Speaker 1: with the metal. One of the things you had to
Speaker 1: deal with was iron oxide, which forms on the surface
Speaker 1: of iron exposed to air. Also, I should mention that
Speaker 1: iron oxide is actually an imprecise term, or rather it's
Speaker 1: a term for a bunch of different chemical compounds made
Speaker 1: up of iron and oxygen, and the iron oxide we
Speaker 1: know of as rust is just one form of that. Gradually,
Speaker 1: humans figured out how to build more robust forges and
Speaker 1: they could heat up or enough so that they could
Speaker 1: actually smelt iron, but it took some more time for
Speaker 1: anyone to really be able to reliably create steel. An
Speaker 1: exception was meteoric iron as an iron from space. Some
Speaker 1: meteorites contained alloys of iron and nickel, and the process
Speaker 1: of entering the Earth's atmosphere created enough heat to do
Speaker 1: essentially the smelting work for us. But this wasn't exactly
Speaker 1: plentiful stuff, so it's mostly used in small ornaments and
Speaker 1: things like that until we got more up to speed,
Speaker 1: like you might be say an Egyptian pharaoh with a
Speaker 1: meteoric iron dagger buried with you next to a gold dagger,
Speaker 1: because that's how valuable these things were. One of the
Speaker 1: things about iron that made it harder to work with
Speaker 1: is that it does oxidize rapidly upon contact with the air.
Speaker 1: Oxidization is a process in which a substance like an atom,
Speaker 1: an ion, or a molecule loses electrons in a chemical reaction.
Speaker 1: Now this does not necessarily involve oxygen, but oxygen is
Speaker 1: a pretty effective electron thief. Iron oxidizes pretty quickly. Oxidation
Speaker 1: is an exothermic reaction. Now that means that as a
Speaker 1: byproduct of this reaction there is a release of heat.
Speaker 1: So you can actually see the effects of oxidation on iron.
Speaker 1: It is what causes iron to rust. So iron in
Speaker 1: the presence of oxygen and water is going to rust.
Speaker 1: But even iron that's not actively rusting will have a
Speaker 1: layer of iron oxide on the surface of the iron itself.
Speaker 1: The process of oxidation is also pretty darn fast. If
Speaker 1: you were to expose a very small speck of iron
Speaker 1: to the air, it would oxidize and heat up and
Speaker 1: you would see a spark. So if you've got a
Speaker 1: lot of iron that's in a lump, you're gonna have
Speaker 1: more volume compared to surface area. Right, You've got more
Speaker 1: iron in the lump than is exposed on the surface,
Speaker 1: just because of the size. This is all about volume,
Speaker 1: and only the surface of the iron is oxidizing with
Speaker 1: the air because you know, the rest of the iron
Speaker 1: is shielded from the it's inside the lump. The heat
Speaker 1: from that oxidizing reaction, the oxidation will be able to
Speaker 1: dissipate into the rest of the lump of iron. Again,
Speaker 1: you've got that big volume of iron, so the heat
Speaker 1: from that process doesn't really amount too much in the
Speaker 1: grand scheme of the lump. But if you have a tiny,
Speaker 1: tiny speck of iron, well, now the ratio of surface
Speaker 1: area to volume has totally changed. There's very little volume
Speaker 1: in a tiny piece of iron. The surface will still
Speaker 1: react to oxygen, and there isn't so much iron inside
Speaker 1: the spec for the heat to dissipate so effectively. So
Speaker 1: the spec gets really hot, hot enough to glow. When
Speaker 1: someone uses a power grinder on iron and you see
Speaker 1: sparks fly, or they're using flint and steel, those sparks
Speaker 1: are tiny specks of iron oxidizing at a super fast rate.
Speaker 1: Iron oxide isn't the stuff we want, right, we want iron,
Speaker 1: So smelting helps us remove iron oxide and get iron instead.
Speaker 1: It goes through the set type of reaction we call
Speaker 1: this one reduction. Smelting also helps separate the iron from
Speaker 1: other impurities that could be in the ore, stuff like sulfur, phosphorous, silicon,
Speaker 1: things like that. Now, as far as the actual smelting process, that,
Speaker 1: as we will learn, evolved a great deal over time.
Speaker 1: The earliest furnaces used to smelt iron, we're called bloomer eyes.
Speaker 1: There's some great videos on YouTube that show how these
Speaker 1: bloomers worked. I highly recommend you guys go on YouTube
Speaker 1: and look up bloomery b l o O m e
Speaker 1: r Y because these videos are equal parts fascinating and terrifying.
Speaker 1: So typically, you would build a chimney like structure and
Speaker 1: you would use something like clay to make it. So
Speaker 1: imagine a a stack a chimney made of clay. You
Speaker 1: would have a little section in the very front that
Speaker 1: would be cut out like a door, but you would
Speaker 1: have a a piece of clay that fit into that.
Speaker 1: You would have at least one hole cut in the
Speaker 1: side of the chimney called a two year, and this
Speaker 1: would allow for more air circulation to go into the
Speaker 1: chamber of the bloomery. If you blue air into it,
Speaker 1: you would increase the temperature of the burn. So you
Speaker 1: would possibly have bellows attached to this, either operated by
Speaker 1: hand or later by having a water wheel turning a
Speaker 1: cam that would allow these bellows to open and close
Speaker 1: and thus blow air into the bloomery, or you might
Speaker 1: just be dependent upon the wind, which wouldn't be the
Speaker 1: most efficient way to make this stuff. You'd also typically
Speaker 1: have a hole towards the very bottom of the chimney
Speaker 1: that would allow you to draw off slag. This would
Speaker 1: be the the hot melted mixture of impurities, and you
Speaker 1: don't have to worry about melting off the iron having
Speaker 1: the iron pour out along with the slag, because that's
Speaker 1: just not going to happen. We're not talking about temperatures
Speaker 1: high enough to melt iron at this point. Conversely, the
Speaker 1: entire bloomery, if you didn't have this way of tapping
Speaker 1: it so that you can put get slag out, you
Speaker 1: might even have to push it over, which sounds incredibly
Speaker 1: dangerous to me, and then allow the molten slag to
Speaker 1: to pour out the top of it. Now, slag typically
Speaker 1: contains a little bit of iron in it as well,
Speaker 1: but for the most part you're talking about all the
Speaker 1: other stuff that you wanted to remove, leaving as much
Speaker 1: of the iron behind as possible. So you might have
Speaker 1: little chunks of iron in the slag, and thus you
Speaker 1: might want to keep the slag just in case has
Speaker 1: any iron in it in order to use in a
Speaker 1: future burn. But to facilitate the removal of slag, forgers
Speaker 1: or you know, smith's or metal or just however you
Speaker 1: want to call them, would typically add in a substance
Speaker 1: with a relatively low melting point that could help siphon
Speaker 1: out some of the impurities. That would act almost like
Speaker 1: a lubricant, if you can think of it that way,
Speaker 1: The bind with things and and be liquid in order
Speaker 1: to help coax more of those impurities to flow out.
Speaker 1: The stuff is called collectively flux, and flux can be
Speaker 1: made up of lots of different stuff, including sand or
Speaker 1: silica or limestone, but with ancient bloomer eyes, often the
Speaker 1: flux came from the material used to build the bloomery itself.
Speaker 1: It would just be leached out of the interior of
Speaker 1: the bloomery and become part of the mixture, so you
Speaker 1: didn't necessarily have to add more in the process of
Speaker 1: smelting and refining iron. This way is laborious. It involves
Speaker 1: getting the furnace really hot with a layer of charcoal
Speaker 1: at the base of the furnace. Then you add more
Speaker 1: charcoal to heat up the entirety of the furnace, and
Speaker 1: then you start adding in equal amounts of iron ore
Speaker 1: and charcoal every few minutes, and you alternate between them, um,
Speaker 1: but you add them both at around the same time.
Speaker 1: So you do, all right, let's put in a kilogram
Speaker 1: of iron ore and a kilogram of charcoal, and then
Speaker 1: after a few minutes another kilogram of iron or and
Speaker 1: another kilogram of charcoal. You have to keep doing this
Speaker 1: over and over and over again every few minutes for
Speaker 1: several hours. So these bloomerys couldn't get hot enough, as
Speaker 1: I said, to actually melt the iron ore outright. Instead,
Speaker 1: you would produce what was called a bloom thus bloomery.
Speaker 1: This would be a mass of hot iron and kind
Speaker 1: of you know, charcoal. Mixt year, the iron doesn't get
Speaker 1: hot enough to really melt, but it's hard enough to
Speaker 1: be kind of a spongy looking material that was somewhat
Speaker 1: malleable if you were to pull it out of the
Speaker 1: bloom moraine then hit it with a hammer. Managing this
Speaker 1: process is tricky because not only do you have to
Speaker 1: maintain that high level of heat, you also have to
Speaker 1: make sure that the two year remains clear of material.
Speaker 1: Remember that's the air channel, where air is either blowing
Speaker 1: in from the wind or you're forcing it in through
Speaker 1: something like a bellows. A lot of stuff can go
Speaker 1: wrong in this process, and even when everything goes corre directly,
Speaker 1: you might not end up with a great amount of iron,
Speaker 1: depending upon the quality of the ore itself. Once the
Speaker 1: process is done, it's time to retrieve the iron bloom.
Speaker 1: So you've tapped out the slag, You've let the slag
Speaker 1: run out. You pull the door off the furnace, assuming
Speaker 1: that or the bloomery, assuming that the bloomery has a door.
Speaker 1: You might even just break the bloomery open. Often these
Speaker 1: were just one use devices. You would construct one every
Speaker 1: time you want to do one of these, and uh
Speaker 1: you might have to break it apart anyway, because sometimes
Speaker 1: the iron bloom would be too large to fit through
Speaker 1: the door in the first place. Now the bloom will
Speaker 1: have absorbed some charcoal would be incorporated into it. Charcoal
Speaker 1: has a very high carbon content, and at higher temperatures,
Speaker 1: iron absorbs some of that carbon. This also lowers the
Speaker 1: melting point for iron a little bit, and that will
Speaker 1: become important later on. The charcoal needs to burn really
Speaker 1: thoroughly for of this process to really work, Otherwise you'll
Speaker 1: get chunks of charcoal that are too large, and you'll
Speaker 1: end up with iron that might have big chunks of
Speaker 1: unburned charcoal embedded in it, which is going to be
Speaker 1: harder to get rid of. But if the coals are
Speaker 1: the right size, the iron will absorb some carbon, but
Speaker 1: not all of it obviously. So now you've got a
Speaker 1: big old, porous lump of red hot iron with some
Speaker 1: carbon and maybe some charcoal. You've got some other stuff,
Speaker 1: and it some slag is still inside that, because again
Speaker 1: it's spongey, it's porous, so there will be slag contained
Speaker 1: inside this red hot bloom of iron. So what do
Speaker 1: you do then, Well, that stage the iron still isn't
Speaker 1: terribly useful, so you would have to reheat the mass
Speaker 1: so that it's malleable. You know, get it hot enough
Speaker 1: so that you can work it. Then you put it
Speaker 1: on an anvil and you start beating that iron bloom
Speaker 1: with a hammer. This compresses the mass. It forces the
Speaker 1: molten slag out of the lump to the surface of
Speaker 1: the iron. So remember I said it's like a sponge,
Speaker 1: it's porous. This is kind of like squeezing out a sponge.
Speaker 1: If you have a sponge that's absolutely saturated with water
Speaker 1: and you start to squeeze it, you force the water out.
Speaker 1: That's kind of what's happening when a blacksmith starts hammering
Speaker 1: an iron bloom with a hammer. You're forcing that slag
Speaker 1: out to the surface. You can watch videos of blacksmiths
Speaker 1: doing this process on YouTube. Again, it's fascinating. You're gonna
Speaker 1: see this sort of glowing orange mass of iron. But
Speaker 1: it will start to grow darker as it's getting hammered,
Speaker 1: not just because it's cooling off. I mean that is happening,
Speaker 1: but it's also growing darker because the slag is being
Speaker 1: forced towards the surface of the mass. So smith's need
Speaker 1: to hammer out the mass folded back in on itself
Speaker 1: and repeat this process over and over. Reheating it, hammering
Speaker 1: it out, folding it back on itself, welding it to itself,
Speaker 1: reheating it, hammering it out. This takes a lot of time,
Speaker 1: and you'll see that typically a relatively large bloom that
Speaker 1: you'll get out of a bloomery will ultimately reduce to
Speaker 1: a much smaller size once the smith has hammered out
Speaker 1: most of that slag, what is left is typically a
Speaker 1: hammered piece that is mostly iron with a very low
Speaker 1: carbon content less than point zero eight percent carbon compared
Speaker 1: to iron, and some other impurities are in there too.
Speaker 1: Because the smith had to work the mass by hand
Speaker 1: to produce this, we call it wrought iron w r
Speaker 1: o U g h T iron. That means worked iron.
Speaker 1: That we had to do work on it in order
Speaker 1: to make it this way. So once in a while,
Speaker 1: using this method of bloomery's you could produce steel. It
Speaker 1: wasn't necessarily predictable. You weren't necessarily going to be able
Speaker 1: to do it time and time again, but it did happen,
Speaker 1: and you'd be really happy whenever it did. Sometimes, however,
Speaker 1: that steel would be particularly hard but brittle. Gradually, mill
Speaker 1: Or just learned that by plunging very hot steel. We're
Speaker 1: talking about steel. This around nine degrees celsius into water.
Speaker 1: The cool steel's surface becomes extremely hard and brittle. But
Speaker 1: by reheating that steel to a temperature of around four
Speaker 1: hundred degrees celsius, in a process that was later called tempering,
Speaker 1: the material will become less brittle but still retain a
Speaker 1: lot of its hardness. So you would hear these terms
Speaker 1: by blacksmith talking about tempered steel. That's what they're referring to.
Speaker 1: But here's the thing. The process for making steel was
Speaker 1: imprecise and dependent on so many factors, including the quality
Speaker 1: of the ore being used to smelt the iron and
Speaker 1: the process to create the actual steel. It was hard
Speaker 1: to dial into the specific ratios you need to go
Speaker 1: from iron to steal in those times. So the concentration
Speaker 1: of carbon really determines what kind of metal you end
Speaker 1: up with. If you don't have enough carbon, you end
Speaker 1: up with wrought iron. If you have too much carbon,
Speaker 1: you end up with cast iron, two very different extremes.
Speaker 1: It's got to be just right, and for a couple
Speaker 1: of thousand years, that was pretty hard to do. Now,
Speaker 1: when we come back, I'll talk a bit about how
Speaker 1: humans figured out more effective ways to produce iron and steel.
Speaker 1: But first, let's take a quick break. We've looked at
Speaker 1: the oldest method of smelting iron with bloomers, and a
Speaker 1: bloomery gets the job done, but it's not terribly efficient.
Speaker 1: You have to pour in a lot of labor and
Speaker 1: a lot of iron ore and a lot of charcoal
Speaker 1: to get any results, and the bloom you produce still
Speaker 1: needs a lot of work to turn it into iron
Speaker 1: that can be put to any good use. So what
Speaker 1: was really needed was a better way to reduce the
Speaker 1: iron oxide and iron ore to iron, and one of
Speaker 1: the best ways to do that is to produce even
Speaker 1: higher amounts of heat. Now let's think about this chemically.
Speaker 1: I've mentioned that the oxidizing reaction is exothermic, but I
Speaker 1: haven't really talked about what's going on here at an
Speaker 1: atomic level. So with iron oxide, you've got iron and
Speaker 1: oxygen effectively bond with one another within a furnace. The
Speaker 1: intense heat and the presence of carbon allows for the
Speaker 1: separation of oxygen from iron. The oxygen instead bonds with
Speaker 1: the carbon forming carbon monoxide, which is an odorless and
Speaker 1: toxic gas. The carbon monoxide is happy to take on
Speaker 1: another oxygen atom as well, So at temperatures around six
Speaker 1: D nine D degrees celsius in a furnace, you'll end
Speaker 1: up with iron and carbon dioxide as well, not just
Speaker 1: carbon monoxide but carbon dioxide. The bloomers just weren't going
Speaker 1: to get the job done. They weren't going to get
Speaker 1: to those temperatures. So that brings us to the blast furnace.
Speaker 1: The bloomery produces a hot of lump iron. It gets
Speaker 1: hot enough to glow and it's malleable at that temperature,
Speaker 1: but it's not hot enough to melt. Blast furnaces can
Speaker 1: reach higher temperatures high end, so that you're not just
Speaker 1: reducing iron oxide to iron plus carbon monoxide or carbon dioxide.
Speaker 1: You're also getting a hot enough chamber so that you
Speaker 1: can melt the iron completely. You get molten iron liquid metal.
Speaker 1: So how is this possible? Well, first, blast furnaces are
Speaker 1: much bigger than bloomery's. They tend to have a chimney
Speaker 1: like structure, much like your typical bloomery, but instead of
Speaker 1: being made out of clay, they're usually made out of
Speaker 1: several layers of brick that form the chimney. Sometimes with
Speaker 1: other materials to provide both stability and often away for
Speaker 1: heat to dissipate. They can be a couple of stories tall,
Speaker 1: whereas a bloomery might only be a couple of meters tall,
Speaker 1: maybe three or four meters for the really big ones,
Speaker 1: and like a bloomery, blast furnaces have two years through
Speaker 1: which pumped air can enter into the furnace. The pumps
Speaker 1: or bellows could be operated by hand, but later on
Speaker 1: it was far more convenient to locate a furnace next
Speaker 1: to a source of flowing water and then use a
Speaker 1: water wheel to provide the power needed to pump the bellows.
Speaker 1: You are in effect blasting the combustion in the furnace
Speaker 1: with air. Thus you have a blast furnace. Unlike people,
Speaker 1: the water doesn't need to take a break, and the
Speaker 1: furnace could be kept at a high consistent temperature, assuming
Speaker 1: it was being fed with fuel regularly like a bloomery.
Speaker 1: Metal orgists would feed a blast furnace by pouring iron
Speaker 1: ore fuel and flux down into a chimney like furnace
Speaker 1: from the top of it. A description of a typical
Speaker 1: blast furnace says that to charge a furnace that is
Speaker 1: to prepare it for the process of smelting iron. First,
Speaker 1: workers called fillers would empty around twenty baskets of charcoal
Speaker 1: into the furnace through the top. The bottom of the
Speaker 1: furnace would be lit, and so you would have combustion
Speaker 1: going on inside the furnace, and the hot gases created
Speaker 1: from that combustion would start heating up the charcoal that
Speaker 1: was further up the stack. Soon the heat would reach
Speaker 1: a stage where the heat of rising gas would be
Speaker 1: enough for the whole smelting process would start as soon
Speaker 1: as you start pouring charges in through the top, and
Speaker 1: a charge at this point is that mixture of iron ore,
Speaker 1: charcoal and flux. So after they get this started with
Speaker 1: those twenty baskets full of charcoal, they would add in
Speaker 1: around oh, I don't know, seven hundred pounds of iron ore,
Speaker 1: followed by limestone. So within half an hour the charge
Speaker 1: level would have sunk down by about ten ft. So
Speaker 1: you're looking at this chimney that was effectively full of material.
Speaker 1: Now that material has sunk in ten ft because of
Speaker 1: that combustion and and the conversion of these solids into
Speaker 1: gases and slag. So then you would add in more
Speaker 1: iron ore, more charcoal, more limestone, and then a bit
Speaker 1: more iron ore at the end, and you repeat that
Speaker 1: process every so often as the furnace burns down, working
Speaker 1: in shive to keep the furnace working the entire time.
Speaker 1: You know, you have to keep on going because if
Speaker 1: you lose this, if you let the furnace go cold,
Speaker 1: then that's a whole thing and you have to start
Speaker 1: all over. Essentially. Inside the furnace, you've got a few
Speaker 1: different areas. So if we were looking at a cross
Speaker 1: section of a furnace at the very base, we would
Speaker 1: see a section that's called the crucible. This is the
Speaker 1: bottom interior part of the furnace. This is where the
Speaker 1: molten iron will eventually collect more on that in a second.
Speaker 1: Above the crucible is an area called the bosch b
Speaker 1: O s H. This is where the furnace temperatures get
Speaker 1: hot enough to reduce iron oxide and ultimately melt iron
Speaker 1: into molten iron. Above the bosch, you've got the stack,
Speaker 1: which is where all your charges are. The intense heat
Speaker 1: in the furnace increases as you get lower down into it,
Speaker 1: allowing for this chemical reaction for iron oxide to reduce
Speaker 1: to iron and as iron got hotter, it melts, and
Speaker 1: because it's so heavy, it's so dense, it sinks to
Speaker 1: the very bottom of the blast furnace. Because just because
Speaker 1: the iron has gone from solid to liquid doesn't mean
Speaker 1: it's no longer dense. It still is. And the slag
Speaker 1: that is all the impurities that were in the iron
Speaker 1: ore plus stuff like the flux that you're adding in
Speaker 1: UH typically again in the form of limestone, would float
Speaker 1: on top of the layer of iron because it's it's
Speaker 1: not as dense. So it's kind of like when you
Speaker 1: mix water and oil together, the denser material is going
Speaker 1: to be at the bottom, right, So taps near the
Speaker 1: base of the furnace. These are pipes that lead into
Speaker 1: the furnace would allow mel or just to tap off
Speaker 1: the slag and also to drain out the molten iron.
Speaker 1: Now that molten iron would typically follow a channel from
Speaker 1: the tap and go down the channel and flow into
Speaker 1: molds on either side of the channel. So while a
Speaker 1: blacksmith would have to work a bloom for ages and
Speaker 1: a bloomery in order to turn it into a bar,
Speaker 1: a blast furnace produces liquid iron that then flows into
Speaker 1: molds and just cools into bars big labor saver there
Speaker 1: right well. In addition, while blue Morays use charcoal as
Speaker 1: a fuel of choice and blast furnaces, once charcoal became
Speaker 1: scarce because people were cutting down all the forests, they
Speaker 1: started to move toward coke. Now, I don't mean the
Speaker 1: soft drink instead, I mean the carbon rich fuel that
Speaker 1: we produce by heating either oil or coal in a
Speaker 1: chamber that doesn't have air in it. Now, if you
Speaker 1: don't have air in a chamber and you add heat,
Speaker 1: you cannot have combustion. Combustion or fire needs three things, right.
Speaker 1: You need fuel, you need heat, and you need an oxidizer,
Speaker 1: of which oxygen is one. But if you're burning something
Speaker 1: or heating something in a chamber that has no air,
Speaker 1: you can't really burn it. You can only heat it up.
Speaker 1: And in this case you can convert stuff like coal
Speaker 1: or oil into coke. The higher temperatures inside a blast
Speaker 1: furnace would allow the iron inside it to absorb more
Speaker 1: carbon than you would find in a bloomery. I think
Speaker 1: of it kind of like how I think of how
Speaker 1: sugar will dissolve into hot tea much more readily than
Speaker 1: it would in cold tea. Chemically, we're not talking about
Speaker 1: identical processes here. I don't want to make you think
Speaker 1: that it's exactly the same thing. It's just sort of
Speaker 1: an analogy I use. Also, it's a reminder that if
Speaker 1: you want to make sweet ice tea, you don't do
Speaker 1: it by dumping sugar in a cold glass of tea.
Speaker 1: Don't don't try that stuff around me. I'm from the South,
Speaker 1: but this is tech stuff, not simple syrup stuff. So
Speaker 1: I'll get back on topic whether the blast furnace is
Speaker 1: using charcoal or coke as a fuel. In the end,
Speaker 1: you produce molten iron which can be tapped to run
Speaker 1: into that channel and it splits off into those molds
Speaker 1: down the length of the channel, forming bars of iron.
Speaker 1: Somewhere along the way, someone thought that this channel with
Speaker 1: the mold that split off to either side kind of
Speaker 1: looked a bit like a sow, as in a female
Speaker 1: pig suckling her piglets. And so the name for this
Speaker 1: type of iron is called pig iron. If you've ever
Speaker 1: heard of pig iron, this is where he gets his name.
Speaker 1: He gets his name because of those channels that ran
Speaker 1: from the blast furnace and split off into these molds
Speaker 1: for pig iron. Bars. Pig iron typically isn't an end
Speaker 1: goal in of itself. It's a starting point for metalworking.
Speaker 1: So the production of pig iron is really about taking
Speaker 1: the stuff that comes out of the ground, whether from
Speaker 1: bogs or mines or whatever, and separating the metal from
Speaker 1: most of the other stuff it's stuck to. But pig
Speaker 1: iron still has a lot of impurities in it and
Speaker 1: way too much carbon for most uses. Remember, carbon hardens iron,
Speaker 1: but it also makes it way more brittle. Often pig
Speaker 1: iron has too many impurities and too high a carbon
Speaker 1: content to be used as cast iron. Cast iron has
Speaker 1: between two point one and four carbon in it, and
Speaker 1: pig iron can have more than that. It also can
Speaker 1: contain other impurities like manganese, sulfur, silicon, and phosphorus, and
Speaker 1: those things affect the qualities of iron as well. If
Speaker 1: there are high levels of impurities, iron workers will heat
Speaker 1: the pig iron in another type of furnace quite similar
Speaker 1: to a blast furnace, and adding other components to help
Speaker 1: remove some of those impurities, to combine and form another
Speaker 1: form of slag, and to tap that slag and move
Speaker 1: the carbon percentage lower. In the same process, liquid cast iron,
Speaker 1: which is you know that high carbon content iron with
Speaker 1: fewer impurities than your general pig iron is liquid. Cast
Speaker 1: iron can be poured into casts to form stuff, thus
Speaker 1: its name. So if you want to make a cast
Speaker 1: iron skillet, first you had created cast out of something
Speaker 1: like sand, so you would carve out the shape of
Speaker 1: a cast iron skillet that way. It's essentially a skillet
Speaker 1: shaped cavity inside a sand block. And then you would
Speaker 1: pour molten cast iron into that sand block, and you
Speaker 1: would allow it to cool inside the sand block and set.
Speaker 1: After doing so, you can break the cast open and
Speaker 1: you've got yourself a cast iron skillet, though you'd still
Speaker 1: have to do a few more steps to treat it
Speaker 1: before you could actually use it as a skillet. But
Speaker 1: the big problem with this type of iron is that
Speaker 1: once it has cooled, you can't easily heat it up
Speaker 1: and work it again, meaning shape it. You can't really,
Speaker 1: you know, heat it up and hammer it and knock
Speaker 1: it into a new shape. The iron is just too
Speaker 1: brittle wrought iron, which has a much lower percentage of carbon.
Speaker 1: In fact, wrought iron typically has less carbon in it
Speaker 1: than steel does. It is much more easily worked if reheated,
Speaker 1: so there needed to be a pro says to refine
Speaker 1: pig iron to get rid of some of that carbon
Speaker 1: and some of the other impurities if you wanted to
Speaker 1: make wrought iron or steel on a much more efficient
Speaker 1: sort of mass production kind of basis. Because as it stands,
Speaker 1: you could make cast iron pretty easily, but wrought iron
Speaker 1: was still hard to do. You were typically still using
Speaker 1: bloomer eas and those just didn't produce on very large scales.
Speaker 1: One advancement in iron working that made this possible was
Speaker 1: the development of special forges called fineries and chaferies, each
Speaker 1: of which did something special. So the finery forge was
Speaker 1: where a finer this is the person working at the forge,
Speaker 1: would take pig iron and they would put it into
Speaker 1: a smallish furnace. The finer would use bellows, usually water
Speaker 1: powered bellows, to blast more air on the pig iron
Speaker 1: as it was being reheated inside this furnace. This would
Speaker 1: cause an oxidation reaction. It would remove some of the carbon,
Speaker 1: which would vent out as carbon monoxide. It would combine
Speaker 1: with the oxygen that was being blown into the furnace,
Speaker 1: or you might even get carbon dioxide, and this would
Speaker 1: leave more pure iron behind. So you're kind of leaching
Speaker 1: out some of the carbon of the pig iron, bringing
Speaker 1: it closer to the type of iron you would find
Speaker 1: in a bloom in a bloomery from centuries earlier, and
Speaker 1: this was typically called a half bloom. The finer would
Speaker 1: then remove this half bloom and then another forgeman would
Speaker 1: take the half bloom and place it on an anvil
Speaker 1: under a water powered trip hammer. What the heck is
Speaker 1: a trip hammer. Well, imagine you've got a lever, okay,
Speaker 1: like a see saw, but you don't have the pivot
Speaker 1: in the middle of this lever. It's closer to one
Speaker 1: side than the other. So on the long end of
Speaker 1: the lever, which would typically be in the down position
Speaker 1: because it's heavier, you have the hammer, and on the
Speaker 1: short end you have that connected close to a cam.
Speaker 1: Cam is a wheel in this case, it's got some
Speaker 1: projections on it and those projections can make contact with
Speaker 1: the short end of the lever. So as the wheel turns,
Speaker 1: it pushes down on that short end of the lever
Speaker 1: and it starts to lift the other side. So the
Speaker 1: hammer goes up in the air. But as the cam
Speaker 1: continues to rotate, it eventually rotates to a point where
Speaker 1: it loses contact with the short end of the lever.
Speaker 1: It's like if you were to push down on a
Speaker 1: seesaw and then pull your hand away very quickly. So
Speaker 1: the trip hammer starts to strike the half bloom and
Speaker 1: does so several times, pushing out impurities that are otherwise
Speaker 1: trapped inside the iron, just as the blacksmith would with
Speaker 1: the bloom from a Bloomery. The process has to happen
Speaker 1: several times, so the half bloom has to be reheated
Speaker 1: and then hammered again and again until it can finally
Speaker 1: be forged into a bar of wrought iron called an
Speaker 1: and coney. The end coney would then be put into
Speaker 1: the chaffery. Chaffery is a hearth style furnace, and the
Speaker 1: bars would undergo reheating before being hammered out into de
Speaker 1: carbonized iron. While this would bring us back to a
Speaker 1: similar kind of iron produced by Bloomery's, the process was
Speaker 1: still more efficient from a labor standpoint, particularly with the
Speaker 1: use of water power, so you could do it faster
Speaker 1: than you would if you were to use the old
Speaker 1: Bloomery method. When we come back, we'll move on to
Speaker 1: some other developments in iron and steel production. But first
Speaker 1: let's take another quick break. We've talked a lot about iron,
Speaker 1: and by wie, I mean i've talked a lot about iron.
Speaker 1: What about steel? So, steel has a carbon content that
Speaker 1: typically puts it between wrought iron and cast iron. Wrought
Speaker 1: iron generally has less carbon than steel. Cast iron has
Speaker 1: more carbon than steel. The carbon content and steel affects
Speaker 1: the steel's weight, hardness, and melting point, as well as
Speaker 1: it's malleability versus brittleness. But if pig iron has too
Speaker 1: much carbon in it and wrought iron has too little
Speaker 1: iron in it, how do you make steel? Well? Typically,
Speaker 1: in days of your you'd have to take wrought iron billets.
Speaker 1: You can think of those as just iron bars for
Speaker 1: simplicity sake, and you would put them in clay pots
Speaker 1: along with some charcoal. So layer of iron bars, layer
Speaker 1: of charcoal, layer of iron bars, layer of charcoal all
Speaker 1: the way to the top. And then you would close
Speaker 1: these clay pots so that they were essentially airtight, and
Speaker 1: you put them into a large kiln called a cementation furnace.
Speaker 1: You would fire up the kiln and it would heat
Speaker 1: up all the clay pots filled with these mixtures of
Speaker 1: iron and charcoal, and it would cause the heated iron
Speaker 1: to absorb some of the carbon that was in that charcoal.
Speaker 1: And in case you're keeping track, yes, we've talked about
Speaker 1: a process in which you add carbon to iron oxide
Speaker 1: and you get a high carbon iron called pig iron.
Speaker 1: You then refine that in a finery and a chaffery
Speaker 1: to produce a low carbon type of iron called wrought iron.
Speaker 1: And then you use the wrought iron and add carbon
Speaker 1: back into it in order to get steel, which does
Speaker 1: sound pretty crazy, right, like a very laborious process to
Speaker 1: go from iron ore to steal. To make it even
Speaker 1: more complicated, this kiln heating process was typically done multiple times,
Speaker 1: with the iron reforged after heating and then put back
Speaker 1: into pots with charcoal. Again, this was to ensure homogeneity
Speaker 1: throughout the metal. You wanted that carbon to be distributed
Speaker 1: evenly throughout the iron as much as possible so that
Speaker 1: you would have really consistent iron. During the heating process,
Speaker 1: one of the byproducts was once again carbon monoxide. The
Speaker 1: forming of carbon monoxide gas would cause blisters to form
Speaker 1: on the surface of the metal inside these pots, so
Speaker 1: we came to call this type of metal blister steel.
Speaker 1: We call this process a carburization process, which means to
Speaker 1: use a heat treatment process in which iron is absorbing
Speaker 1: carbon in order to become steel, or you might use
Speaker 1: it with steel itself in order to make a more
Speaker 1: high carbon form of steel. So if you want to
Speaker 1: make steel around this time, it either involved a decent
Speaker 1: amount of luck so that you were using a bloomery
Speaker 1: and the iron bloom you produce just happen to have
Speaker 1: the right amount of carbon and lack of impurities in
Speaker 1: it to qualify as steel, or you need to go
Speaker 1: through a series of refinement processes from smelting or into
Speaker 1: pig iron, to refining the pig iron wrought iron, to
Speaker 1: refining the wrought iron and too steel and making wrought
Speaker 1: iron this way took a long time too. Then a
Speaker 1: fellow named Henry Court came along in sevent four. Court
Speaker 1: found that by heating pig iron in a furnace at
Speaker 1: temperatures high enough to melt it, because remember pig iron
Speaker 1: has a lower melting point than other kinds of iron,
Speaker 1: and then by stirring this mixture in the presence of
Speaker 1: oxidizing substances, he could produce wrought iron much more efficiently
Speaker 1: than the old finery forge process. This new process was
Speaker 1: called puddling, or since I'm from the South, I'm gonna
Speaker 1: call it pudlin. This process was one in which the
Speaker 1: iron wouldn't actually be in contact with the fuel, and
Speaker 1: most of the other versions you're putting the iron ore
Speaker 1: in the same chamber where the fuel is burning. Not
Speaker 1: with puddling, the puddler what that's what they were called,
Speaker 1: would use these really long iron tools to reach into
Speaker 1: the furnace bed and violently stir the semi molten pig iron,
Speaker 1: and the stirring action would help separate the iron from
Speaker 1: the impurities, and in the process of oxidizers, it would
Speaker 1: really help create that separation. This was done repeatedly with
Speaker 1: the puddler eventually removing this ball of refined iron from
Speaker 1: the furnace using really long tools. And the key thing
Speaker 1: about this process is that even with the constant stirring
Speaker 1: and vigorous stirring of the puddler, it was much faster
Speaker 1: than using a finery where you were putting those pots
Speaker 1: inside a furnace over and over again, and you could
Speaker 1: produce wrought iron relatively fast, and it would become one
Speaker 1: of the important contributors towards the Industrial Revolution as a result,
Speaker 1: because wrought iron was desperately needed for big construction jobs,
Speaker 1: you know, like building railroads. Still, steel production was more limited,
Speaker 1: with most of it being made in the form of
Speaker 1: blister steel. An Englishman named Benjamin Huntsman further refined steelmaking
Speaker 1: by taking blister steel and melting it inside clay crucibles
Speaker 1: and incredibly hot furnaces reaching temperatures around six degrees celsius
Speaker 1: it's about twenty degrees fahrenheit, and then the molten steel
Speaker 1: could be poured into casts, much like cast iron could be,
Speaker 1: but with the benefits of steel. The next big development
Speaker 1: in steel production came in eighteen fifty six thanks to
Speaker 1: English inventor Henry Bessemer. Now to be totally fair, Bessemer
Speaker 1: was one of a few people to suss this out.
Speaker 1: There was also an American named William Kelly who came
Speaker 1: up with the general same idea independently. Bessemer was trying
Speaker 1: to find a means to produce steel and greater quantities
Speaker 1: and at lower expense. His approach, which he called the
Speaker 1: manufacture of iron without fuel, sounds kind of terrifying, honestly. First,
Speaker 1: you take molten pig iron yikes. So when a process
Speaker 1: begins with molten hot metal, you know you're getting into
Speaker 1: some hardcore engineering. But next you blow oxygen through the
Speaker 1: molten iron mix. The oxygen reacts with the impurities in
Speaker 1: the pig iron and effectively creates oxides that end up
Speaker 1: as slag, and the slag just gets tapped off separately
Speaker 1: from the iron itself. The oxidizing reactions were exothermic, so
Speaker 1: they generated eat that provided heat that could be harnessed
Speaker 1: to keep this iron from solidifying, so the reaction would
Speaker 1: help sustain itself this way, the result was the rapid
Speaker 1: production of steel, very low carbon steel. Other inventors and
Speaker 1: middle are just figured out that by adding some other
Speaker 1: stuff like manganese, iron and carbon into the mix. So yes,
Speaker 1: once again we are adding carbon, the carbon content of
Speaker 1: the steel could be increased while remaining impurities like sulfur
Speaker 1: could be neutralized. The resulting steel was a much more
Speaker 1: pure version than the typical kind produced in older methods,
Speaker 1: and it could be made quickly and cheaply. For the
Speaker 1: first time in history, steel was easy enough to manufacture
Speaker 1: to make it a viable material for stuff like construction.
Speaker 1: The one impurity that the original Bessemer converter wasn't really
Speaker 1: good at removing was phosphorus, which was unfortunate as that
Speaker 1: stuff was fairly common in the iron ore of Europe.
Speaker 1: Sydney Gilchrist Thomas invented the variation of the Bessemer converter
Speaker 1: that incorporated limestone that helped strip phosphorus from the iron mix.
Speaker 1: And it did have one other problem this approach, which
Speaker 1: is that the original converters would introduce small amounts of
Speaker 1: nitrogen into the iron ore, thus introducing an impurity making
Speaker 1: the iron a little more brittle. This was hard to
Speaker 1: correct for it was hard to get a pure source
Speaker 1: of oxygen at this point in history. In the mid
Speaker 1: nineteenth century, William or Wilhelm Siemens, who was German but
Speaker 1: was living in Englands or right back to Old Blighty,
Speaker 1: tried something new that would create an alternative to the
Speaker 1: Bessemer converter. He rigged up a furnace so that the
Speaker 1: escaping hot gases from the furnace would heat up a
Speaker 1: chamber filled with a lattice of bricks so the bricks
Speaker 1: would absorb this heat. Then he would change the flow
Speaker 1: of air so that the incoming air used to feed
Speaker 1: the furnace would first pass through these bricks lattices, and
Speaker 1: that would preheat the incoming air and you would get
Speaker 1: hotter furnace temperatures as a result, So it was essentially
Speaker 1: creating a hot blower versus a cold blower. Unlike the
Speaker 1: best of our process, Wilhelm's furnace, called an open hearth furnace,
Speaker 1: was slow. But while it wasn't as fast as a
Speaker 1: Bessemer converter, it allowed for far more precision when you
Speaker 1: were making the steel, so the quality control was much better.
Speaker 1: The end product was molten steel, so you could even
Speaker 1: cast that into ingots right away. The open hearth furnaces
Speaker 1: could take steel scraps as a charge, thus cutting down
Speaker 1: on waste. So let's say you make some steel it's
Speaker 1: not as good quality as you would like. You could
Speaker 1: put it in an open hearth furnace and it could
Speaker 1: be used as a charge to create your next batch
Speaker 1: of steel that could be better. It could also process
Speaker 1: pig iron. It became a popular method of steel making
Speaker 1: for a century. Alright, we're getting into the home stretch
Speaker 1: of this steel making episode. In night, a Swiss inventor
Speaker 1: named Robert Durer improved upon the Bestimer converter from a
Speaker 1: century earlier. He invented a process called basic oxygen steel making.
Speaker 1: It's not using basic oxygen, it does use a highly
Speaker 1: pure form of oxygen. Rather, the term basic actually refers
Speaker 1: to the use of chemically base materials, again for the
Speaker 1: purposes of removing impurities that are in pig iron. Like
Speaker 1: the Bestimer process, basic oxygen steel making forces oxygen through
Speaker 1: molten pig iron, but the process is totally wicked. So
Speaker 1: imagine you've got a big container that's lined with a
Speaker 1: refractory material, meaning it it reflects heat back into the
Speaker 1: chamber itself. This container is called the ladle. Inside the ladle,
Speaker 1: you pour molten pig iron. Suspended over the pig iron
Speaker 1: inside the ladle is what is called an oxygen lance.
Speaker 1: So imagine a pipe through which ultra pure oxygen can
Speaker 1: blast out, hitting the molten pig iron at supersonic speeds.
Speaker 1: The lance itself has to be actively cool to typically
Speaker 1: water cooled, to keep it from overheating from the intense
Speaker 1: heat from this furnace. The oxygen reacts with the impurities,
Speaker 1: thus you get oxidation and it creates heat through that reaction,
Speaker 1: and the heat sustains the temperature needed to keep the
Speaker 1: furnace in action, it becomes sustaining. So in many ways,
Speaker 1: it's a more advanced version of the best Americ converter.
Speaker 1: And this became a new method for making steel efficiently,
Speaker 1: with fewer impurities and at a faster rate than open
Speaker 1: hearth furnaces. All right, we've got one more method to
Speaker 1: talk about, or at least to introduce, and we'll really
Speaker 1: talk about it more in the next episode, and then
Speaker 1: we'll also explore about all the different types of steel
Speaker 1: like Nick had asked. So, the final type of furnace
Speaker 1: I need to mention here is the electric arc furnace,
Speaker 1: and it heats up the materials inside the furnace the
Speaker 1: charge through an electric arc rather than by burning some
Speaker 1: sort of fuel. Back in the early nineteenth century, Sir
Speaker 1: Humphrey Davy created an electric arc between two carbon electrodes.
Speaker 1: In fact, we had electric arc lamps before we had
Speaker 1: the incandescent light bulb, and these things were terrifying too.
Speaker 1: They generate a light by by creating this electric arc
Speaker 1: between two electrodes, very high voltage electric arc. And it
Speaker 1: didn't take very long before someone thought, huh, I wonder
Speaker 1: if there's enough energy in that electric arc to you know,
Speaker 1: melt metal like iron. This is the same basic technology
Speaker 1: that would go into electric arc welders. While using an
Speaker 1: electric arc was effective early on, it was also inefficient
Speaker 1: and expensive, which made it less viable as a means
Speaker 1: of mass producing steel. And there's a lot more of
Speaker 1: tech to go into with that, but I think that's
Speaker 1: enough for today's episode. In our next episode, we'll pick
Speaker 1: back up with electric arc furnaces, talk about how they
Speaker 1: really work, and then finally we'll talk about the different
Speaker 1: classications of steel and what they all mean, including maybe
Speaker 1: a discussion about Damascus steel, because that stuff is largely misunderstood,
Speaker 1: so we'll cover that in the next episode. Two. Uh.
Speaker 1: If you guys have suggestions for things I should cover
Speaker 1: in future episodes of tech Stuff, let me know. Send
Speaker 1: me a message on Twitter or Facebook. The handle for
Speaker 1: both is tech Stuff hs W, and I'll talk to
Speaker 1: you again really soon. Text Stuff is an I Heart
Speaker 1: Radio production. For more podcasts from I Heart Radio, visit
Speaker 1: the i Heart Radio app, Apple Podcasts, or wherever you
Speaker 1: listen to your favorite shows.