This is a transcript of the Gastropod episode, The Barrel That Could Save A Forest, first released on September 28, 2021. It is provided as a courtesy and may contain errors.

MATT FORTRAN: This is what we’re getting out today. This is our order. This is for Sazarac, in Kentucky. These are all whiskey barrels. And they need to get shipped out today. There’s 100 of them. We still have like 40 to finish.

CYNTHIA GRABER: Barrels! I’ve tasted delicious wine and whiskey and beer and more that were aged in them, but I’d never seen them actually being built before!

NICOLA TWILLEY: But on our first reporting trip post-vaccination, we headed straight to Oregon Barrel Works. It’s one of the few cooperages left in America—a cooper is a person who makes barrels, so the barrel factory is technically a cooperage. Bonus factoid: If you meet someone with the last name Cooper, one of their distant ancestors probably made barrels.

GRABER: And this episode is indeed all about barrels, you’re listening to Gastropod, the podcast that looks at food through the lens of science and history, I’m Cynthia Graber—

TWILLEY: And I’m Nicola Twilley. And yes, it’s an episode about barrels, but it’s also the story of the small team working to save a unique Western landscape by making barrels. With whiskey in them.

GRABER: Some of the best barrels around do have whiskey in them, in my opinion.

TWILLEY: On our way down this barrel rabbit hole, we discovered a lot of weird stuff, like why barrels are so important to creating the flavors of our favorite wines and whiskey—and why people don’t age wine in mahogany. Turns out the wood really matters—in fact, whiskey wouldn’t taste anything like whiskey without a barrel.

GRABER: We also discovered the origins of the word “bung hole.” Which I’d thought only referred to your rear end. I was wrong.

TWILLEY: All that plus the science of spoofulation. Also, I should say that this episode partly came about because my husband Geoff has been asking for a Gastropod episode on barrels for, hmm, five years now?

GRABER: Geoff, we’re here for you. Eventually. Gastropod is part of the Vox Media podcast network, in partnership with Eater.

MATT HOFFMAN: Well, our whole focus is to make American single malt that is reflective of the Pacific Northwest. So when we started the distillery, the goal was to make something that is just reflective of this place.

GRABER: On our very first post-vaccination reporting trip, we also made a point of visiting Westland in their distillery in the industrial neighborhood of south Seattle. Because Matt Hoffman, who’s co-founder of Westland—he’s making some really unusual whiskey that is deeply rooted in the Pacific Northwest.

TWILLEY: Matt started this project by swapping out the standard ingredients of commercial single malt for ones that came from closer to home.

HOFFMAN: Local peat, which is a big project we’ve worked on for, gosh, close to 10 years now. And then different barley varieties. So even just within the one style of single malt, there’s just a ton of room to explore.

GRABER: Barley is obviously key—that’s a key grain in whiskey. Single malt whiskey? That’s made from barley that’s been malted, or softened in water until it just starts to germinate. And there’s plenty of barley in Washington State.

TWILLEY: Peat is used for the fires that dry the malted barley—and it also adds those smoky flavors that are so delicious. Scotland consists mostly of peat, and so that’s where most of the peat in peated whiskeys comes from.

GRABER: There does happen to be peat in Washington, but nobody had used it for whiskey before. It’s a little more complicated than just substituting it for Scottish peat, but Matt’s been working on it, and he has local peated whiskey aging in his barrels right now.

TWILLEY: So, with the barley, the peat, and obviously the water all sourced locally, what was left was the barrels. Matt looked at his barrels and they were made from American white oak, which grows in eastern and central US, but not the west.

HOFFMAN: So okay. Is there anything else that grows here?

GRABER: Nearly all barrels for aging booze, wine as well as whiskey, anywhere in the world are made from oak. We’ll get into why that is later, but it’s true—and honestly the majority of those barrels around the world, including the ones Matt was using—they’re made from American white oak.

HOFFMAN: That is the workhorse of basically the whiskey industry globally. It grows everywhere. It grows very plentifully.

TWILLEY: Convenient, cheap, but not local. Matt knew that there are something like 500 different species of oak in the world, they’re all in what’s called the Quercus family. Quercus alba is the American White Oak, but the west does have plenty of its own quercii. Or quercum. Or querca. Quercuses. Whatever.

HOFFMAN: I mean, this species here, Quercus garryana, only grows here in the Pacific Northwest. And not only does it only grow here, but as the only white oak species that grows here.

GRABER: Let’s drop the Quercus. Garryana oaks, they’re also known as Garry for short, so Garry it is. Garry Oaks grow exclusively between two mountain ranges on the west coast, which are the Cascades and the Coast range, which is also called the Olympics.

HOFFMAN: And it only grows between these two mountain ranges—like 50 miles wide—it’s the perfect and only climate in which it grows. So it’s like this I-5 corridor from essentially Vancouver, BC, down through almost to San Francisco.

TWILLEY: Now, I have to say, when you drive the I-5 up through Oregon to Seattle, you don’t see a lot of oaks. It’s mostly sprucey looking.

HOFFMAN: So as a Pacific Northwest native, right, so I grew up here, I had no idea that we had oaks. You know, we associate the Pacific Northwest so much with evergreen trees—Doug fir and things like that. But the most amazing thing about Garry Oak is the backstory.

GRABER: The backstory starts a mere ten thousand years ago. Ice sheets covered the Pacific Northwest. And then things warmed up, and the ice melted.

HOFFMAN: So as the last glacial lobes retreated to the north, this oak that was growing in California began to migrate north, into the Willamette Valley, eventually here into the Puget Sound. And then up to Vancouver Island, and a little bit into what is now Southern British Columbia.

TWILLEY: People—Native Americans—enjoyed eating the acorns that this Garry Oak dropped.

HOFFMAN: But the other thing that was happening was that deer and elk were noticing these acorns here, and were like, Okay, this is great. This is amazing food for us. So they’re coming here and happily eating all these acorns. And, and essentially what was happening was Native Americans are realizing, okay, this is the perfect trap.

TWILLEY: The acorns were luring in all this delicious four-legged meat, and the oak trees themselves grow far enough apart to make it easy to hunt.

GRABER: And the deer and elk that were lured in by those acorns, they became particularly tasty. It’s just like the super famous Spanish ham, the jamon iberico, where the pigs eat tons of acorns and their meat ends up fatty and kind of nutty and it is delicious.

TWILLEY: But there was trouble in paradise because fir trees were also growing in this Garry Oak savannah.

HOFFMAN: Because oaks are deciduous, they’re only growing, you know, during the spring and summer part of the year, whereas fir trees will grow faster.  And if a fir tree grows next to an oak, and the oak is shaded out, the oak will die. So if left completely to its own devices, the fir trees would wipe out oaks here in the Northwest.

GRABER: If that happened, so much for this incredibly tasty dinner for the Native Americans. But fortunately, they had a trick up their sleeve. Because Garry Oak is pretty fire resistant, and Douglas fir isn’t.

HOFFMAN: What they did over thousands of years was practice controlled burns through these Garry Oak savannas that would remove any competing species, any fir species, any other things that would compete with the oaks. And so what you’d end up with is these kind of—they look like plains, like farmland almost. But you’d have these oaks and they’d be big and dispersed around.

GRABER: Yay! Plenty of Garry Oaks, plenty of acorns, plenty of room to hunt down delicious elk and deer!

TWILLEY: And then, guess what, it’s that age-old story: Europeans show up and screw everything up.

HOFFMAN: People came in and said, this looks like excellent farmland, which it would be and it is still today, you know, in the 1850s 1860s, and cut 95% of it down. Because they had no idea what they were dealing with. And you see a lot of you know, Garry Oaks especially prominent in the Willamette Valley, as well as on Vancouver Island around Victoria. But it’s, you know, almost all gone relative to what used to be out there.

GRABER: And this is why nearly the entire Pacific Northwest looks like an evergreen forest and there’s almost no oak savannahs to be seen.

TWILLEY: But there are still some Garry Oaks standing. And Matt did some research and some digging, he read a research paper on the chemistry of Garry Oak wood, and he found one guy in the Willamette Valley in Oregon who was making barrels from it for some wine-makers who wanted to try it out.

GRABER: Garry Oak might be rare, and it is protected in some places, but not on a state level. And most of it is on private land, so this guy gets his logs from trees that fall or maybe get cut down when people want to build on that land.

HOFFMAN: So we began working with—this is Oregon Barrel Works—began working with him in 2011. And sourcing, at first it was five casks at a time.

GRABER: Matt didn’t really know what was going to happen. He didn’t know how the whiskey was going to taste when he tried to age it in a Garry Oak barrel, but the only way he was going to figure it out was to give it a try.

SOUND OF POURING

HOFFMAN: So the glass on your left is a pure Garry Oak cask sample. So this, you know, right away, is clearly different from American white oak.

TWILLEY: The whiskey aged in Garry Oak was clearly a different color— it was a darker warmer reddish brown, whereas whiskey aged in white oak is that typically caramel whiskey color that you expect. So we appreciated the color, we sniffed it like pros, and then we tasted it!
GRABER: I would have sworn sherry aged.

HOFFMAN: Yeah, exactly. A lot of people say the same thing. There’s a dark fruitiness to it. It just turns everything dark is the way that I like to think about it.

TWILLEY: Westland doesn’t sell this neat Garry cask whiskey, and also it’s still super young—it’s fiery. But when I tried it, to me it tasted like Christmas pudding—dried fruit, dark sugar and maybe some clove.

GRABER: I have never had Christmas pudding, but I agree, it’s like raisin-y and molasses-y and so incredibly delicious. And it’s totally different from whiskey aged in the other kind of American oak.

TWILLEY: We actually loved it, but for Matt the sweetness and heaviness was a little much.

HOFFMAN: You know, the first thing here, when we tried to after three months, we were like, Holy smokes this, it’s like drinking Kansas City style barbecue sauce.

TWILLEY: Which is great in a meat based context, obviously, but not exactly what he was going for.

GRABER: So Matt’s been experimenting by blending whiskey aged in Garry barrels with whiskey he’s been aging in American white oak. He poured out a sample of the first bottling they sold of one of these new blends.

GRABER: I get more of the vanilla-y that that I didn’t get at all before. And the really intense, like, raisin molasses is like way toned down. Like it’s there, you still get the fruit, but it’s not nearly as prominent.

HOFFMAN: So you know with American white oak, you get caramel. In Quercus garryana, it’s molasses.

TWILLEY: That’s what makes this super fascinating: you can literally taste the difference between whiskey made in barrels of these two different oak species: Garry and American white oak. This is not a subtle nuance like when people are like: Oh I’m getting notes of roasted plums and leather. It’s really distinctive. You would not have a problem telling the difference in a blind taste test. So what on earth is creating that difference? What is going on between the alcohol and the wood?

HOFFMAN: So the first thing is flavor extraction. So that’s the easiest thing, that’s what most people understand.

GRABER: Okay, so flavors can be extracted from barrels. That sounds logical, but we wanted to figure out a little bit more about how this works, so we called up Aude Watrelot, she specializes in the science of wine at Iowa State University.

AUDE WATRELOT: And I’m working closely with the industry, the wine industry of Iowa and the Midwest, trying to improve what we know about the grape and the wine chemistry and trying to improve, I would say, the grape and wine quality of Iowa and the Midwest.

GRABER: What happens when wine and whiskey are hanging out in barrels, it’s slightly different, but overall, the science is pretty much the same.

TWILLEY: And in both cases, the wood you use really matters. Different woods and different species of oaks contain different chemical compounds—which means that there are different flavor chemicals available to be extracted by your alcohol, depending on which wood you store it in.

GRABER: We mentioned there are 500 species of oak, but really only four are used for barrels. There’s American white oak, that’s one.

HOFFMAN: You have a couple of oak species in Europe. So you’d see these more in the world of cognac, and especially in wines and French wines. And you sometimes see them being imported to the US to make wine casks that they want to use French oak. And then you’ve got mizunara oak from Japan, and mizunara oak from Japan was something that came about, basically, when the Japanese couldn’t source American white oak, especially around World War Two, and they began looking for their local oak species—it’s really, really rare. So that became very popular in the whiskey industry. But it’s very difficult to find, very difficult to source. I would personally love to get my hands on some of that just to experiment with it, but the cost of it is astronomical as well.

GRABER: Before single malt whiskey is aged in one of these oaks, it tastes just kind of like barley moonshine, there is a barley-esque flavor to it, but whiskey experts say about 80 percent of the flavor comes from the barrel. And if it’s an American white oak barrel, you might get a pretty strong hit of vanilla and coconut.

HOFFMAN: French oak doesn’t have that, or has a very low quantity, I believe. Garry Oak, what we’re using here with the garryana project, doesn’t have any of that at all.

TWILLEY: What’s going on is that American white oak trees just produce those vanilla-flavored molecules in their wood—they’re actually the exact same chemicals people use to make artificial vanilla flavor. French oak produces chemicals that taste more like caramel and baking spices, less sweet and less full-on than American white oak. And Mizunara, which I got a hold of in Japan—it tastes super different again—it’s like sandalwood incense.

GRABER: So in the barrel, the whiskey, or the wine, it’s soaking just a little bit into the wood, and then soaking back out. Alcohol is particularly good at extracting flavor molecules—you can do that at home, by soaking lemons in vodka to make limoncello, or you can use ethanol to make your own vanilla extract. And so the alcohol is pulling the wood flavors out of the wood and into the booze.

TWILLEY: But that’s not the only thing that’s happening in the barrel.

WATRELOT: So you will have oxygen coming from outside into inside. And that will help the color stability, that will help the texture, so the astringency perception of the wine, which is the drying sensation you can have when you drink a red wine, that’s supposed to decrease a little bit.

TWILLEY: So let’s break that down. As oxygen seeps in through the pores in the wooden barrel, a few different things start happening. The oxygen reacts with both the molecules in the wood and the molecules in the booze, and it rearranges them.

GRABER: And those rearrangements—in red wine, they create more stable color pigments, so those lovely ruby tones.

TWILLEY: And then for both wine and whiskey, oxygen-triggered reactions help some of the flavor molecules that are floating around clump together into larger, more complex flavor compounds.

GRABER: Another kind of molecule that clumps together are the tannin ones. Think of that kind of mouth-drying feeling—over time oxygen helps tannin molecules link up together and so they become big enough and heavy enough to fall out as sediment. So, like Aude said, a red wine that starts out really tannic before being aged in a barrel ends up with kind of a softer mouth-feel.

TWILLEY: So you might think, if oxygen is doing all these great things, why not just leave your whiskey or your wine sitting out in a vat, why enclose it in a barrel in the first place?

WATRELOT: Because you don’t want to have oxidation of your wine. That’s not the purpose.

GRABER: Fast oxidation, like just leaving the top off a big vat of wine? Aude says the flavor molecules that would be created would taste really bad, like rotten apple flavors. You definitely don’t want that.

WATRELOT: The purpose of oxygen transfer, that’s really to have a slight transfer of oxygen during time. So that can be for several months, several years, just to go to have a little bit of oxygen to have some chemical reaction happening, but not in one day.

HOFFMAN: And this is the thing that a lot of people don’t understand, is that a barrel, especially barrel made from white oak, has this perfect blend of porosity, allowing oxidation from the atmosphere, allowing evaporation from the liquid, but also not hopefully allowing the liquid to seep out.

GRABER: Evaporation is the third thing going on through the barrel—just a little tiny bit of the pure ethanol, the alcohol, evaporates through the barrel, then the flavors left behind get even more concentrated.

TWILLEY: So this all explains how barrels can create flavor. But that leads us straight to another question. Why oak? Why is oak so special that it is the wood we make all our barrels out of? That’s where we’re going next, after this word from our sponsors.

MID-ROLL

NATE LINDQUIST: Let’s go with the reason we use oak.

TWILLEY: Nate Lindquist is the cooper at a distillery called Rolling Thunder, part of a company called Rogue. And he took us to see some oak logs stacked at his cooperage on the Oregon coast.

LINDQUIST: And we can see right here, this wonderful pattern here. And these are the medullary rays. And they are part of the wood’s fluid transport system. And those are at 90 degrees to the growth rings. So those are part of how the tree gets its nutrients from the inner to the outer. And those are the primary reason why we started using oak.

GRABER: Nate told us that not all trees have that same type of internal structure. When the oak dries, those medullary rays form an impermeable watertight barrier. Oak just held liquid better than barrels from other trees that people might have tried.

LINDQUIST: So in the old days, they would get to where they’re going, and they would have more product to sell. So it became just the way to go. And over the centuries, we just got used to the flavor.

TWILLEY: Nowadays, barrels are all about flavor. But that wasn’t why people started putting alcohol in barrels. In the past, they put alcohol and basically everything else in barrels because if you put a barrel on its side, it’s amazing for moving stuff around.

HENRY WORK: And this makes the barrel unique as opposed to a flat sided, pail, tub, whatever you want to call it.

GRABER: Henry Work is also a cooper, he’s been one for many decades, and he wrote a couple of very detailed books about barrels, including one called Wood, Whiskey, and Wine: A History of Barrels.

WORK: There’s only a small portion of the barrel that’s on the ground and it makes it very easy to roll a barrel and turn it if the barrel is full of liquid, say, and weighing several hundreds of pounds, which they do. And that was why they were so well utilized, especially in the days of sailing ships. And because the barrels were so maneuverable, men, probably mostly men, could move very heavy barrels weighing thousands of pounds.

TWILLEY: Genius. So who invented this amazing contraption?

WORK: Well, we think the Celts invented it. They knew how to bend wood. They had the forest and they knew how to use tools. So very probably the Celts invented it sometime in the second or third centuries BC. And then the Romans, as they came in and conquered them, adopted the technology and the designs and such.

GRABER: The Celts who at the time lived all over northern Europe, they were famous for their advanced iron working skills. It’s not that other places in the world didn’t have tools and didn’t have wood, but nobody else seems to have invented the barrel independently.

WORK: It’s a good question. Why wasn’t it invented in China or Japan? They certainly had buckets and stuff, you know, big vats and things like that. We don’t know why they didn’t.

TWILLEY: In fact, even in Europe, these Celtic barrels didn’t catch on right away, at least not in the Roman Empire’s homeland in the Mediterranean.

WORK: They didn’t have the forests, extensive forests. They didn’t have experience of using barrels. It’s much drier, barrels tend to dry out. So there were problems to using barrels around the Mediterranean.

TWILLEY: Also, those early Celtic barrels weren’t exactly barrel perfection. We said the Celts were good at making iron tools, but that’s a relative thing—these early tools weren’t super precise and they weren’t super sharp.

WORK: So they wouldn’t have used the hardest woods. They would use softer woods: spruce for maybe elm, birch, things like that.

GRABER: Those early softwood barrels were pretty leaky, unlike the amphorae.

WORK: I’ve looked at a lot of data for barrels even in the 15th century. And shipments would you know arrive with three or four barrels empty because they’d leak during the shipment.

GRABER: Also, soft leaky barrels often were sealed with pitch, which is resin from pine trees. And according to Henry, the pitch added a quote undesirable flavor to wine. And anyway, in the Mediterranean, they already had a system for wine storage—they stored wine in a large pottery vessel called an amphora.

TWILLEY: Amphorae are certainly fine for storage, but they are really heavy, much heavier than barrels, and they could easily break when you shipped wine in them across the Mediterranean.
And as the Romans started building their empire and their troops started spreading out all across northern Europe, supply chains for essentials like wine got pretty long. Transporting the alcohol needed for thousands of soldiers was basically impossible in amphorae. So the barrel eventually triumphed.

GRABER: We don’t know exactly when people started using barrels made of oak in particular—barrels eventually disintegrate, so there’s not a lot of evidence. But Henry says by the year 300 or so, basically all barrels were made of oak. That’s because tools got better, so people could cut harder wood, and there was plenty of hard oak around in Europe, and as Nate told us, dried oak is watertight, so barrel-makers eventually made the switch.

TWILLEY: And then, at some point, people would have noticed that hey, not only is this oak barrel less leaky for moving liquid around, it also makes any alcohol that’s sat in it for a while taste different. So when did that breakthrough happen?

WORK: Well, again, that’s one of the things we don’t know. But we do know that the Romans in the Roman Empire have written about wine that’s been aged, they knew that wine got better, well some wine got better, if it aged. Wine during shipments age, just because the shipments took a long time. If the barrel didn’t leak, the wine often arrived better than when it left. And maybe the captain might attest to that, if he tapped into some of the barrels on the way. Oh, this is getting better and better and better. I think I’ll just keep trying this.

GRABER: So barrels were invented, and then oak became the wood of choice, awesome. You can move booze and make it taste better. And that’s basically where most of the major innovation ended.

WORK: The next big thing would have been steel hoops, the use of steel hoops, and by using the steel hoops, they could get the barrels tighter, and had less leakage.

TWILLEY: One steel hoop had the strength of 6 wooden hoops. So that was definitely an improvement, although to be honest it wasn’t really a revolutionary change. And of course tools got better, especially once the Industrial Revolution began.

GRABER: As industrialization really hit its stride in the 1860s, when the American oil rush began, there weren’t pipelines or steel drums. All that oil had to be stored in wooden barrels, and coopers couldn’t make them fast enough by hand. So there was a big push to invent machines that could speed things up.

TWILLEY: Machines didn’t only work faster, they were also more precise, and so barrels got even less leaky.

WORK: So they’ve definitely improved over the years. But basically the style of the barrel has changed very little in 2000 years. You know, a Roman cooper could walk into a winery today and he’d be in awe of the stainless steel, but he’d recognize the barrel immediately.

NAILING/PUNCHING SOUND

FORTRAN: He is using a punch. So it’s a nail gun with no nails in it. It just has a punch that’s punching through the steel hoops just enough to create a barb into the wood. So the hoops won’t go up and down or back and forth.

TWILLEY: This is Matt Fortran, he works with a guy called Rick DeFerrari at Oregon Barrel Works, which is where Matt Hoffman at Westland gets his Garry Oak barrels from.

GRABER: That nail gun wouldn’t have been around at the time of the Romans, nor would the steel hoops, but the premise is the same. The sides of the barrel are made of long pieces of wood, they’re called staves, and those staves were and are held together by curved hoops. Today coopers use a nail-free gun to secure the hoops so no nails get rusty in the whiskey.

FORTRAN: So we’re going from—we go from log to barrel.

TWILLEY: In that journey, the hoop stage is already a way down the line. First, a cooper has to age his logs: Matt showed us huge piles of wood that had been aging for nearly three years to get to the right moisture level for wine barrels. Then you have to cut your logs, which is a whole other thing—you can’t just saw them like regular planks.

WOOD CLACKING

LINDQUIST: And this is an example of a log which we had quartersawn.

GRABER: Nate, that cooper from Rolling Thunder, he actually trained with Rick, and the warehouse where he builds his barrels is about an hour away from Rick, so we visited both. In case it’s not obvious, a quartersawn log is a log that’s literally split down the center of the log in four, so you get four long quarters with a sharp right angle in the center.

TWILLEY: This quartersawn business is not just for fun or aesthetics, it all goes back to those medullary rays in the oak. After a tree is cut down, those little pores tighten and shrink and they create an impermeable layer that makes oak super watertight—if you line your cuts up correctly.

FORTRAN: So what we’re attempting to do with quartersawn is get the growth rings parallel, and those medullary rays at 90 degrees to that which, like I said, prevents the fluid from migrating out.

GRABER: And then at this point you cut the staves out of the pieces of wood. Each eight to twelve foot log provides enough wood to make the staves for one or two barrels.

TWILLEY: Then there’s a bunch of fancy sawing to shape the edges of the staves. And then Rick told us the real magic begins.

RICK DEFERRARI: There’s no set width to the staves, they’re all random width, the wood is so valuable that if we had to cut it, you know, two inches, two and a half inches, we’d lose so much wood. So there’s no set number of staves in the barrel. We just know we need to have this circumference for that size barrel. And so you know, we just kind of lay it out. It’s basically you just start putting pieces till you find the last one that kind of makes it tight.

TWILLEY: It’s like a jigsaw puzzle, Rick lays all these slightly different width staves out on a table and swaps them in and out to get to the right width for a barrel.

GRABER: After Rick puts his barrel puzzle together, the staves are laid out flat. It just looks kind of like a wooden fence of different widths of planks that only touch in the middle of the planks—each stave is thinner at the ends and a little thicker in the middle. So how do you take this mess of planks and curve them and smush them together into a barrel?

SOUND OF DRAGGING SOMETHING HEAVY

LINDQUIST: This is the trickiest part of the whole process. This is raising up. So raising up hoop: Grab each one, one at a time. Put it in, lock it in place, you really have to have good thumbs for this.

TWILLEY: It is super tricky—Nate grabbed a big metal hoop and put the end of the first stave up against it, inside the hoop. Then he slid the next stave next to it, sort of wedged up against it, and then the next one, and the next one.

LINDQUIST: And then just grab them, tuck them in place and work around. I’m not gonna do the whole thing here, because this takes about 20 minutes and when I have an audience, I tend to get distracted and drop them.

TWILLEY: Nate may have stopped halfway, but as he worked his way round the barrel, what was nuts was that the staves stayed put, even when he wasn’t holding the ones back at the start, just because of how wedged up against each other in the metal hoop they were.

GRABER: At the end of the hoop raising, the result is a thing that looks kind of like a narrow teepee or maybe a hula skirt, with a hoop at the top and sticks fanned out from the hoop. That’s not a barrel. The staves have to curve, they have to bend.

FORTRAN: People always think a lot of times that you bend with water or bend with steam—you bend with fire. And so these fire pots will get up to about 600 degrees inside the barrel without burning it. It’s kind of remarkable. And the barrel becomes really plasticky.

TWILLEY: Matt showed us the fire pots—they look like slightly more hardcore versions of the chimney you’d use to light your charcoal for your Weber grill.

GRABER: Basically they use those chimney-like devices to get a controlled fire going on in the barrels that they’ll keep glowing for about 45 minutes to an hour and a half, to get the staves just bendy enough so that they don’t break when they’re forced into barrel-like curves.

TWILLEY: As soon as the staves are all nice and plasticky, our coopers use this really weird looking machine with a whole bunch of these octopus-like hydraulic arms to pull the staves at the open end of the teepee together, and then they slip on a temporary hoop to hold everything in place. And then you get something that sort of looks like a barrel.

GRABER: Then they toast the inside of the barrels. They keep the fire pot burning slowly for maybe a couple of hours to get the inside of the barrel to look like nice amber-colored toast.

LINDQUIST: The cooking term is the Maillard reaction. And that’s basically altering the wood sugars to get a different flavor and color profile. It’s almost like making caramel.

GRABER: And the flavor compounds that are created by toasting are kind of like that, caramel-y and vanilla-y. And those compounds get pulled out by the alcohol, as we described.

LINDQUIST: It’s wonderful. Yeah.

TWILLEY: Nate knows when he’s toasted his barrel perfectly because it smells so freaking good.

LINDQUIST: I get a basic idea from looking at it, the color, but then when I get the… Oh, probably the best comparison is if you know the smell that you get from 85% cacao chocolate just right before it liquefies. That’s what that’s the smell I’m going for.

GRABER: I can imagine that, and it would smell fantastic.

TWILLEY: Traditionally, only wine barrels get toasted, but Rick started doing it for whiskey too, and people seem to like it.

GRABER: With whiskey, coopers don’t usually toast, instead they light the inside of the barrel up with a huge blazing flame. Today, Rick first toasts his whiskey barrels, and then he sets the whole thing on fire.

TWILLEY: This is a process called charring and it doesn’t happen to wine barrels, just whiskey. It’s a really different process—toasting is like slowly baking cake in a warm oven—you take your time to create those golden, toasty caramelized flavors.

GRABER: And charring, that’s like getting out your blow torch and making the surface of your creme brulee bubble, or setting your bananas foster on fire.

TWILLEY: Or, you know, the inside of your barrel.

FORTRAN: With whiskey, just build a big fire in here, let it go. And then we use a blowtorch. Just light this and go around on the inside of the barrel till it catches on fire. I mean the flame will shoot almost to the ceiling in here. And then the big piece of metal over there that’s leaning? Just slap it on top, snuff out the flame. Let it rest for a few minutes. So from lighting it on fire to putting that on is about maybe three to five seconds.

TWILLEY: This part of the barrel making process is super dramatic.

FORTRAN: It is pretty cool. It’s really, really hot. In fact, my arm hair is just now growing back.

GRABER: We asked Matt if he gets singed every time. He said, Yeah, every single time.

FORTRAN: So you know, the fire pot is inside the barrel and we got to keep stoking it with little pieces of wood. You know, reaching in all the time, and your arm hair just gets singed off. I’ve lost my eyelashes, and my eyebrows.

GRABER: The char does a bunch of things to the barrel, too. First of all, the flavors it creates are even stronger than the toasty ones. Second, the color: pre-barrel, the whiskey is clear, and the charcoal layer in the wood gives the whiskey that beautiful amber that people now think is whiskey-colored. And Matt at Westland says the char also helps get rid of flavors you don’t want.

HOFFMAN: So a lot of those are sulfur based, one of the most amazing things about charred casks—which all whiskey barrels are charred these days—is that the interior carbonization of a charred cask will trap and remove sulfur compounds.

TWILLEY: Charring for the triple win. And by now, we’re nearly there with our baby barrel. They cool it down, they pop off the temporary hoops, they sand it. Then they stick it in this heavy duty machine called a hoop driver to put on the permanent hoops that keep the barrel really tight.

WHIRRING SOUND

FORTRAN: You can see that you can see the force, you know it’s pushing with almost 3000 PSI to get that hoop on. It shouldn’t go anywhere.

GRABER: And then after the hoops are on tight, they drill a hole in the barrel, you know, so you can get the whiskey or wine out. That hole gets sealed with a cork.

FORTRAN: There’s your bung hole.

TWILLEY: Excuse me!

GRABER: Yep, a bung hole originally referred to a barrel hole, and apparently the words came to represent a butt hole at least by the 1600s, when it first showed up in print as slang.

FORTRAN: So we choose the widest stave. Obviously center it as best as possible. This is our bung boring machine, just a drill.

TWILLEY: Then they fire up the flame thrower.

FORTRAN: So this is an acetylene torch. And we use it to heat up the bung tool there. That cauterizes the bung.

GRABER: Cauterizing a bung does sound really painful, but I’m told it’s a humane process.

TWILLEY: Once the bung is sorted, the barrel needs a top and bottom too, just to add to the kink. But what’s wild is that even those flat parts are complicated because every single barrel is a slightly different size and circumference because of that whole stave jigsaw puzzle.

FORTRAN: So we compass them to find the radius to find the exact size of every single barrel. So every head is cut specifically for the barrel.

GRABER: We watched Rick cutting a barrel head.

DEFERRARI: It’s really high tech, it actually has a laser on it. Put the head in there. Line it up. Close the door. This cutter is gonna go in there. Head’s gonna turn. It’s gonna cut that angle.

GRABER: Wow, look at that!

DEFERRARI: Yeah, pretty nice, huh?

TWILLEY: Tada. Pop the lid on and Bob’s your uncle, except for the final step, a little quality control.

FORTRAN: We just fill it with water, and we just let it go till it’s full, turn it off and then wait for leaks. If it doesn’t leak after about a minute, you know, it’s gonna be fine.

GRABER: The oak staves are now beautifully bent, they’re tightly held together by steel hoops. But what’s kind of amazing is that Nate says if you took off the hoops, those staves would stay bent.

LINDQUIST: So I’ve got staves over on the rack from barrels that we disassembled five years ago, and they’ve still got almost all of that curvature.

TWILLEY: Once you’ve coopered a barrel, it’s coopered. But coopering itself—the art of making barrels—that nearly disappeared. That story coming up, after this break.

MID-ROLL

GRABER: Rick’s been coopering for about 30 years. He was turned on to it because when he was backpacking through Europe, he started working at a winery, and next thing you know, he’d put away his Eurorail pass and started apprenticing with a cooper.

TWILLEY: But when he wanted to start his own business in the U.S., it was almost impossible to even find equipment—he had to buy century-old stuff from France.

DEFERRARI: When I started, there was nobody but now there’s, you know, a handful of people kind of doing it again, which is good to see, because it is kind of a dying art, you know. But as you can see, it’s hard, dusty, hot work.

TWILLEY: At one point, it must have seemed as though the art of coopering would never die. Henry told us that in the 1800s, barrels ruled the world. Tens of millions of them were used to move everything: beer, cheese, crackers, salted fish, pickles, sugar, flour, petroleum. Everything.

WORK: There was probably—this is a rough guess. Maybe 5,000 coopers in North America and Europe. And it’s dropped down to less than 100 now.

GRABER: Why did barrels go away? Well, container ships with all those huge rectangular shipping containers that big cranes lift off and on those ships. Wine doesn’t even usually get shipped in barrels these days, instead it travels in big plastic bags that are stored in shipping containers and then the wine is bottled when it gets to its destination.

TWILLEY: Barrels started out as a necessity, they were essential for moving stuff, and alcohol, around. But now they’re kind of a luxury. If they’re still used, they’re used because they improve the flavor and color and mouthfeel of whiskey and wine.

GRABER: Whiskey basically has to age in a barrel. That’s what makes it whiskey. But for wine, it’s optional. Maybe only 20 or 30 percent of wine is barrel-aged. Some types of grapes and wine like pinot grigio aren’t improved by being aged in oak, some kinds of wine are aged in maybe steel vats.

TWILLEY: Sometimes a wine maker doesn’t want barrel flavors in their wine. And sometimes it’s a question of money.

WATRELOT: Because using barrels, that’s really good for adding complexity, adding specific aroma compounds, specific characteristics to the wine, but it has an economic sense to think about. So using barrels, that’s something that has a cost.

TWILLEY: Barrels are not cheap. I asked Rick what it would cost me to take one of his barrels home with me.

DEFERRARI: LAUGHS For you? $900.

GRABER: Rick said an industrial American white oak barrel would be around $350, maybe $400. Rick’s are expensive because they’re handmade. His team works on many barrels at a time, of course, but each individual barrel takes about a week from start to finish.

TWILLEY: A French oak barrel is even more expensive, like 11 or 1200 dollars. That’s because the French forests are smaller, so there’s less wood available. And then the government manages the forests really, really carefully so the wood is exquisite and accordingly pricey. And, you know, it’s French.

FORTRAN: I could just tell you wine people are about the most persnickety folk you’ll ever find. Somehow in the history of winemaking we got really stuck on French oak. And they have farmed it sustainably for you know, hundreds of years and it’s valuable. But once you get that in your mind frame, it’s sometimes hard to break out.

GRABER: And wine makers are willing to pay for it. If you’re selling a hundred dollar bottle of wine, the price of the barrel won’t add too much to the overall cost, but if it’s like a 25 or 30 dollar bottle? Henry told us at that point the cost of the barrel is maybe second only to the grapes.

TWILLEY: So winemakers and distillers reuse their barrels. It’s only American bourbon that by law has to go into new barrels of freshly-charred American oak. Scotch whisky makers are thrifty folk, and they often buy those barely used bourbon barrels for much less than they cost brand new.

GRABER: Sometimes thriftiness leads to a delightful outcome—some time ago, Scotch whisky makers had some barrels around that had contained sherry shipped over from Spain, and they used those sherry barrels to make their Scotch, and hey! A delightful new style of whisky was born. Today it’s common to age wine and beer and whiskey in used barrels from other types of booze, to get even more flavors.

TWILLEY: But although we’re all about reuse, Aude told us that a barrel doesn’t actually last forever, at least in terms of flavor.

WATRELOT: Because the more you will use it, the less compounds you will still have.

GRABER: More than half of those compounds leach out the very first year, then they slowly fade away. A barrel stops contributing any flavor notes after about four to eight years, depending on how strong the alcohol in them is. Then you can store liquids in the barrels, but the flavor won’t change like it’s supposed to.

TWILLEY: But because new barrels are so pricey, clever wine people have tried to figure various ways around this. Some coopers will refinish used barrels, they’ll grind off the inside layer of wood to reveal some fresh, flavorful new wood. But you can only do that a couple of times before the staves get too thin.

GRABER: Another creative approach is what’s called spoofulation, it’s trying to mimic what a barrel does without a barrel, we explored this in our episode about the role time plays in food. They’re doing things like putting chips of oak in whiskey containers, or bubbling up slow streams of oxygen.

TWILLEY: Wine snobs call the results “spoofy wine.” And honestly, it isn’t quite the same as real barrel aged. But people keep trying!

GRABER: Meanwhile—and this is bringing us right back to where we started—coopers are getting creative too.

LINDQUIST: We’re calling it the “weird woods” or the “single barrel project.”

GRABER: In his one-man barrel-making shop, Nate is experimenting with making barrels from all sorts of woods for Jake, the master distiller at Rogue.

LINDQUIST: So we’ve done a cherry barrel, which I think turned out fantastically, and then Jake found a buddy of his down in Texas and he got us some pecan wood. So I made a couple of pecan barrels and that is another absolutely fantastic—I wish we had some of the whiskey here, but it all went out.

GRABER: Unsurprisingly, we were bummed we couldn’t taste it.

TWILLEY: Honestly I actually felt it was kind of cruel to tell us about it and then not have any for us to taste.

GRABER: But he didn’t have much, just like there isn’t much of anything that isn’t oak. Some people have experimented with acacia wood, some have tried chestnut. But those wine-makers are mostly using these woods for how they let oxygen in and out, not for their unique flavor chemistry. Still, this isn’t happening much—remember, 99.9999 percent of the barrels used are oak.

TWILLEY: Everyone’s been using oak for so long because it’s great—it’s watertight, it’s bendy, it’s food safe, it’s even a little antimicrobial, it lets oxygen in at just the right rate, and it adds great flavors. What’s not to love?

GRABER: But maybe there’s an even better wood out there, just as watertight and all that other stuff and somehow also an improvement?

WATRELOT: Probably. But yeah, we will have to go through a lot of different woods. And that’s also because we don’t know a lot about all the different types of wood that can be used for barrels.

TWILLEY: Nate is on a quest to fill in those gaps in our knowledge.

LINDQUIST: So what we have here is part of our experimental process. I’ll do toasted sections of the various woods and then mix those in with the whiskey so we can look at the color and get an idea of the aroma and flavor.

TWILLEY: He’s actually borrowing a trick from the spoofulators here.

GRABER: We got to smell a few of his experiments that were aging in glass jars.

LINDQUIST: This is Doug fir.

TWILLEY: I was expecting it to be more sprucey.

LINDQUIST: We were expecting the real resinous aroma, but it’s not showing up. That’s maple.

GRABER: Oh, wow. Smells like—

TWILLEY: It’s got a maple note!

GRABER: Smells like maple!

TWILLEY: That is gonna make a really nice spirit.

TWILLEY: At this point, we were like yeah! Go for it. Make a maple barrel. But it’s not so easy.

GRABER: For one thing, Nate mostly wants fruit and nut trees, because these are usually the tasty and food safe ones, but modern orchards don’t let them grow big enough to become a barrel-sized tree.

LINDQUIST: So anytime we’re going to find something large enough to make, it’s going to be something leftover from a heritage that’s getting knocked down to put in a housing development or something.

TWILLEY: For another, a lot of these woods aren’t easy to work with. When Nate made a full-size barrel of pecan and tried to age whiskey in it, he discovered that pecan is very porous. He ended up having to seal up all the holes up with beeswax.

GRABER: And remember that Garry Oak that is native to the Pacific Northwest and that tastes like molasses? Even though it’s an oak, that’s really tough to work with, too. First of all, there’s very little of it around. And unlike the French forests, it’s not managed and grown for barrels, so the trees are twisty and full of knots.

HOFFMAN: The second big thing is that they will split. It’s more brittle, the Quercus garryana in particular relative to the American white oak. So when you’re working with this wood, you have to be very careful to not let it split, let it check.

FORTRAN: It’s a really, really dense hardwood compared to other oak, which means it’s more difficult to bend, more difficult to cut, harder on the equipment. It’s hearty.

TWILLEY: Still, Rick and Matt at Oregon Barrel Works have figured it out. And alongside experimental distillers like Matt at Westland, they’re gradually building a market for Garry Oak barrels. They’re also trying to rebuild the Garry Oak savannah that European colonizers destroyed.

GRABER: Matt’s working on a restoration project with a local environmental group to replant a Garry Oak savannah near an Air Force base, it’s basically the biggest stand of Garry Oak in the entire state.

TWILLEY: More Garry Oak is great for lots of ecological reasons. Especially as climate change makes the fire risk in the west worse and worse, oak forests are less flammable than some of the evergreens. And oak is a keystone species—it supports tons of native wildlife, from truffles to birds to bears.

GRABER: And of course some of that Garry Oak could be used in a barrel. But Matt is never going to be able to use barrels from the trees he’s planting to age his whiskey.

HOFFMAN: I mean, Garry Oak is so slow growing, you know, it’d be 150 years before you could get enough wood to harvest it.

TWILLEY: In Oregon, Nate is also trying to seed some Garry for the future. He told us about a nice stand of Garry Oak he knows, not too far from his cooperage.

LINDQUIST: Every so often I’ll go down there in the fall and I’ll scavenge up a bunch of acorns and grow those and hand those out. Yeah, I’ve probably handed out about 70 to 80 saplings over the years from here.

TWILLEY: When you work with wood, you have to think long term. If you make barrels, or use barrels, you think about forests.

GRABER: What’s kind of amazing is that—yes, barrels have been made in almost the same way for thousands of years, the equipment Nate and Rick have in their workshops, some of that is a century old. And the entire field of barrel-making is really small these days.

TWILLEY: But there’s still a whole world of new flavors to be discovered.

HOFFMAN: The most fun part about Garry Oak, for me, is that we’re contributing something new. And people have been drinking whiskey their entire lives. People know single malt whiskey really well. And the types of flavor compounds that we’re getting from Garry Oak are just like, really unique. The fact that you can still innovate, and show people something they’ve never experienced before is an immensely cool thing to be able to do.

MUSIC UP

GRABER: Thanks this episode to Matt Hoffman of Westland, Rick DeFerrari and Matt Fortran of Oregon Barrel Works, Nate Lindquist of Rolling Thunder and Rogue, and Aude Watrelot from Iowa State. We have links to their websites, barrels, and whiskey at gastropod.com—where you’ll also find photos and videos of our barrel-making visits. And finally, thanks to Nicky’s husband Geoff for repeatedly suggesting this episode—Geoff, we finally did it!

TWILLEY: Thanks as always to producer Sonja Swanson and to our partners at Eater, as part of the Vox Media Podcast Network. We’ll be back with a freshly charred new episode in two weeks!

GRABER: ‘Til then!