Small distillers (and even big ones) would love to speed up the chemistry that happens inside a barrel, because as long as what they make is sitting in wood, it’s not making money. Technology that could shorten the time between distillation and bottling would be a massive boon to the industry.

A recent article about aging spirits from Punch Ten Speed Press’ lovely online drinks magazine-blog describes a super-science-y way to accelerate the aging of a spirit—which is to say, making it mature faster than it would just sitting in a big wooden barrel. Even today, big wooden barrels are the pinnacle of the technology.

The key to the story is a $5,000 gadget called the Sonicprep that can, apparently, force a distillate to mix with wood chips and extract their flavors in minutes instead of years. Here’s the high-stakes part of the story in case you don’t want to click:

Design-wise, the Sonicprep consists of a sound-insulated chamber with a door and a hole cut in the top, a wand-like “horn” that emits high-intensity sound waves and a control box and power source that connects the wand through a cord. According to David Pietranczyk, the Sonicprep’s wand can deliver pinpointed sound waves into a liquid at rates as high as 20,000 pulses per second. Pietranczyk—a chef working at PolyScience who’s tested the Sonicprep’s culinary applications—talked me through the phenomena at play. The device creates microscopic cavitation bubbles that disrupt and needle their way in between molecules, as well as “minute shockwaves that can rip apart solids.” Basically, the Sonicprep allows liquids to mingle with and pass through porous materials extremely effectively.

A New Orleans bartender named Max Messier mixes housemade distilled apple juice, made with a rotary evaporator, with wood chips and then cavitates the mixture into something almost but not entirely like Calvados.

The technology would appeal not just to modern-cuisine-chasing bartenders, but to distillers looking to cut costs. In addition to delaying a return on investment, time spent in the barrel costs money, in fact, because the distillers have to maintain their warehouses.

That’s why, for example, bourbon distillery Buffalo Trace built its “Warehouse X,” to test things like temperature increases—cycles of higher heat induce a distillate to infiltrate wood more frequently, which is why makers of American whiskey will tell you that it doesn’t need as much age on it as, say, single malt Scotch. And it’s also why a company called Terresentia runs a business with a proprietary filtering and ultrasonic process that, they say, adds the flavor of aging.

More usually, though, it’s why small distillers use small barrels. They get more distillate in contact with more wood in less time.

I visited a couple of barrel makers when I was reporting my book, including one called Kelvin Cooperage. It’s relatively small by the standards of, say, the robot-powered cooperage Diageo built in Scotland or even Independent Stave and the Brown-Foreman facilities here in the US, in Kentucky. Brown-Foreman builds on the other of a couple thousand barrels a day, mostly to feed the rapacious beast that is Jack Daniels; Independent Stave makes perhaps a million a year. “If we make 100 in a day, that’s a pretty good day,” says Paul McLaughlin, one of the brothers who runs Kelvin. “A lot of what we’re doing is for winemakers, taking a barrel and shaving it.” That “rejuvenates” the barrel, planes off a few millimeters from the inside to reveal new wood, ready for new wine. It’s a cheaper option for winemakers than the beautiful, furniture-finished, brand new American or French oak barrels with galvanized steel hoops.

in Napa. Image: Adam Rogers/WIRED

(I asked Yuri DeLeon, a Napa-based account manager for Independent Stave, if the million-a-year number was accurate. He wouldn’t tell me, but he agreed that it was “a lot.”)

One of the rules for making bourbon is that the barrel has to be new, and made of oak. But the rules for a lot of other spirits ask for barrels that once contained something else—you get the flavor of the first fill as well as whatever you’re making. Bourbon barrels tend to be a little less pretty than wine barrels, too. The outsides aren’t sanded to a beautiful white. The hot-roll steel hoops get pitted with rust in the damp warehouse air, and the wood is kiln-dried instead of seasoned for two or three years outside, which means it never acquires the silver-black infection of fungus that eats away at the lignin, exposing the cellulose to the spirit as it ages and sparking all kinds of weird chemistry. Some of the tannins either get leached away or break down, softening flavor.

Independent Stave is an exception here—in addition to the rough-hewn everyday barrels they also make a line aimed at, yes, craft distillers. They air-season the wood for a minimum of two years, and let buyers specify different levels of toast or char. You can buy American oak, French oak, or a hybrid, with American staves and French heads. And the barrels are sanded, and have galvanized hoops. “For the craft distiller we sand it a little better, make it a little nicer,” says DeLeon. After all, that barrel probably won’t be locked away in some dark, never-seen rickhouse. It’ll be on display in the distillery, right behind the still. It has to look good for the customer—and different kinds of barrels can extend a brand, because a distiller can throw the same product into a range of wood and release it under a bunch of different labels. Slick. “You don’t change your process at all,” DeLeon says. “You just change the oak.”

That’s not McLaughlin’s game, though. “The vast bulk of our production is still wine barrels,” he says. “Making new bourbon barrels, that needs to be what you do. It’s high volume and low margin. It’s a cheaper barrel.” Even Kelvin’s wine barrels specify which forest the oak was harvested in—Kentucky or Minnesota (because Minnesota is supposed to have tighter-grained wood, which equals more tannins). “We can do a traditional bend or a water bend in a tank of hot water, as opposed to just spraying it down. And we have like 12 different toast levels,” McLaughlin says. “And then if someone came to us and said, ‘hey, would you try this?’ we would.”

(Kelvin gets its staves from stave mills, second- and third-generation family run, just like Kelvin. They’re harvesting from private land here in the US, and if you ask them about the sustainability of the practices, they’ll say that there are more oak trees growing now in the US than any time in history. They don’t say anything about how old those oak trees are, or what the quality of the wood is. It comes in three grades: Veneer, which is the stuff you use to build furniture with; wine wood; and bourbon wood.)

(In fact, those differences between American barrels and the French style of wine barrel are what put winemakers off American oak for years—still do, in fact. It probably wasn’t the oak, but the manufacturing process, which was at first more like that of bourbon, with kiln-dried wood and a deep char on the interior. Coopers are a bit more sophisticated now.)

But that’s not the core of what Kelvin does. In fact, Kelvin plays a key role in the global spirit business. “The biggest part of our business is dealing in used whiskey barrels,” McLaughlin says. “We buy as many barrels as we can, grade them, repair them, and ship them out.” In other words, after Jim Beam, Makers Mark, Heaven Hill, and Wild Turkey dump their bourbons out of their barrels, they put the barrels on a truck and send them to Kelvin (or similar re-makers). Kelvin rehabs them and puts them into their own cargo containers, bound for Scotland, Ireland, China, the Caribbean, and elsewhere so distillers in those places can age their new-make spirit in ex-bourbon casks from America. “A distiller here wants to empty it, roll it onto a truck, and never think about it again,” McLaughlin says. And overseas, “they want to open the container doors and roll barrels into their filling line.”

It’s not a business McLaughlin expected to find himself in. His father became a cooper at 15 and started the business in Glasgow in 1963, making and rehabbing casks from the US. In 1991 he moved the business to Louisville—it made more sense to go to the source. Paul’s brother Ed actually did a coopering apprenticeship in Scotland; Paul, a big guy with dark curly hair and half a Scottish accent, became a lawyer. He was working in Orange County in California—living in Laugna Beach and working in Fashion Island, actually—when he realized that he hated it out there. Too crowded. “I decided that was enough of that,” he says. That was a decade ago. “It was a good move, and it beat billing hours.”

In practice, that means McLaughlin’s days are barrels barrels barrels. A barrelful of barrels. They are stacked everywhere at Kelvin—outside, pushed against every boundary of the property, stacked high, grey and black in the sun. In the warehouse they’re only allowed to go four high, but that’s still 20 feet. Everywhere they’re not looming, the space is taken up by barrel parts—palettes of staves ready to be milled, bent, and turned into barrels or stacked discs of wood, the heads of the cask. That bready-witch hazel smell suffuses the place. It’s pleasant enough, McLaughlin says, depending on what you were doing the night before.

The thing is, the used bourbon barrels arrive in pretty bad shape. “Every one in here has some different problem,” says McLaughlin, walking between two walls of barrels. “It’s the pressure and releasing. You’ll see quite often the staves are good but an end will blow out.” Or the bung stave will have cracks. “You can see that here,” he says, pointing at a barrel. I look more closely, and sure enough, there are cracks around the hole where the bung would go. “The only way to repair that is to take hoops off and cannibalize other barrels.

McLaughlin walks me through the labyrinth to the actual workshop floor. There’s a sound like a hammer on an anvil; one of the workers is using a mallet and a chisel to knock hoops off a damaged barrel. McLaughlin shouts above the noise. “We watch the width, and we can tell which cooperage a barrel was made in. We’ll find a barrel from that cooperage for the repair.”

Why? I yell back. You’re trying to match the width of the staves?

“It’s really height,” he says. “It’s miniscule, but it makes a difference.” Meanwhile, another worker is getting ready to pop the rivets out of the hoops. They’ll resize them later, so they’re tight. McLaughlin watches hoops come off another barrel—a few sharp strikes of the chisel and the hoop is loose, and then off, one after the other. “There’s a machine to do this, but this is quicker,” he says. Then he invites me to stick my head into the newly splayed open barrel. It’s black, wet, and smells like fruitcake. For a moment I consider licking the staves. Then the worker tips the barrel over, and the bottom head falls out. “See, he found another bad stave,” McLaughlin says. “That’s two he’ll replace.”

But…what happens to the cracked staves? “Barbecue places. Firewood. We try and sell them where we can,” McLaughlin says. “People use them for decoration in bars.

Sometimes the used barrels get completely disassembled. Kelvin packages them like puzzles, wrapped in plastic. These “knockdowns” are easier to ship—as long as the person at the other end has a big enough reassembly operation. “We get 210 standard barrels on a 40-foot shipping container,” McLaughlin says. Then he points at the palletized, disassembled barrels. “You can probably get 390 of those, if you ship heads and hoops as well.” Easy economics: Pay the same for the container, ship almost 200 more barrels. “We typically ship 10,000 at a time.”

That’s a tremendous volume, I say.

“People keep drinking,” McLaughlin answers.

But the real reason big barrels like the ones Independent Stave and Kelvin make haven’t been replaced yet is that the technological tricks and small barrels only replicate part of the chemistry of maturation. They accelerate extraction, which pulls tannins and pigments and sugars out of the wood. But they don’t accelerate oxidation—the attachment of oxygen atoms to the various molecules floating around in the solution—or esterification, the combination of acids and alcohols (usually) into molecules called esters. They can smell and taste pretty great, but it’s tough to speed up the process. Typically, extractives give you new-green, almost piney flavors as well as molecules like lactones (a kind of coconutty, fatty flavor), and oxidation and esterification mellow those out

So I’m a little bit suspicious of the use of a Sonicprep in pseudo-aging. Just as with a small barrel or a filtration process, what you get might taste good, and might look different (or even better) than a distillate fresh out of the still…but it won’t taste old.

Unless I’m missing something. Happy to hear otherwise.