I'm standing in the barrel room of Captive Spirits Distilling in Ballard (1518 NW 52nd St, 852-4794) with distiller and owner Ben Capdevielle, hovering over two well-worn, 53-gallon bourbon barrels. The barrels are branded with words and logos that reveal the journey they took to get here: first, Kentucky, where they held Wild Turkey, then Seattle (Sodo, specifically), where Westland Distillery (2931 First Ave S, 767-7250) used them to age their Peated American Single Malt Whiskey. The barrel doesn't tell us where its wood, American white oak, came from, but it most likely grew in the woods of Missouri or Arkansas.

For the last three months, Capdevielle has been aging his signature product, Big Gin—a traditional London dry–style, juniper-forward gin—in the barrels, and he thinks it's just about time to dump it into a stainless steel tank to rest. He hopes that in around two months' time, it will be bottled and sold as the company's newest product, Peat Barreled Big Gin.

I ask Capdevielle if he plans to use the two barrels in front of us again. He smiles. "No, no, these are moving on. They're going to a brewery." And so the barrels will continue their long, possibly endless journey.

Barrels begin life as strips of thin dried wood called staves, which are handmade by artisans called coopers at shops called cooperages. (If your last name is Cooper, chances are someone in your family made barrels—and, no doubt, casks, tubs, and butter churns.) These days, cooperages exist mainly in service of the beverage industry: Coopers steam staves to make them flexible, and then bend them, gather them, and hoop them together with metal rings.

Most American-made barrels are destined to hold bourbon. (By law, barrels may only be used once to make bourbon.) But before they arrive at distilleries, they are toasted and charred. According to Westland master distiller Matt Hofmann, charring gives them "an inside layer of activated carbon to filter out impurities." It also splinters the wood slightly, making it easier for the spirit to "grab those caramel, coconut, and vanilla flavors."

In Seattle, a community of distillers and brewers has formed around barrel-aging. Barrels are passed back and forth, along with stories of triumphs and failures, tips, and, of course, sips of one-of-a-kind beer, whiskey, and gin.

"It's cool to see a local ecosystem evolve," says Hofmann, noting that Westland's barrels also go on to local distilleries Captive and Copperworks, as well as some breweries. "We're making products with an identity specific to the Pacific Northwest."

Westland's flagship American Single Malt Whiskey is aged in two different kinds of new oak casks: one that holds a heavy char, the other a light char. After years of aging (the exact length depends on what kind of barrel they're in), it'll be tasted, blended, and perhaps tasted and blended a few more times until Hofmann is satisfied with the result.

Aging with wood requires patience beyond just waiting for the passage of time. "Every day, we produce five or six barrels," says Hofmann. "Theoretically, they should be identical if you've put it in five of the same type of cask. But even if the wood came from the same tree, there are differences in wood from the inside or the outside, from the top of the tree or the bottom. As hard as you try to be consistent, each barrel is unique."

Distillers and brewers typically strive for consistency—limiting and reducing factors that might compromise the quality or disturb the balance of flavors of their signature products. It's why liquor is distilled in copper and steel, and beer is fermented in stainless steel tanks.

But barrel-aging chucks all that consistency aside. With liquor, which is sterile, a barrel contributes flavors through its char and natural wood sugars. Beer is a little different. When you age in barrels, you invite in everything you've been trying to keep out: oxygen, extra sugars, booze, and rogue microorganisms like bacteria and yeast, which can all dramatically affect the flavor of the beer. Add in the distinct characteristics of each barrel, and the results can be wildly unpredictable.

Which is what makes it so fun.

"Barrels provide this amazing ecosystem," says Ryan Hilliard, owner of Hilliard's Beer (1550 NW 49th St, 257-4486). "We can take all the beer out of this and wash the inside of it, but all the bugs that flavor the beer live in the barrel, live in the wood. As much as you might clean it, you've got this stuff growing in there, and it just grows from batch to batch."

Hilliard's, which mainly brews Belgian-style beers, began aging in barrels within two months of opening three years ago. Head brewer Todd Garrett had a friend from college working at the Chateau Ste. Michelle winery in Woodinville who was able to get him some chardonnay barrels. "To tell the truth," says Garrett, "we had no idea what we were doing. It was about experimentation."

It still is. On any given day, Hilliard's pours a few of their barrel-aged beers in their adjacent taproom, but you won't find them for sale anywhere around town. "What we do over there," Hilliard says, gesturing toward several steel fermentation tanks in the brewery's large warehouse, "is the product of years of work to build our business." He stops and smiles. "What we do over here is for fun."

"Here" is the farthest corner of the warehouse, surrounded by more than 30 brawny barrels, filled with different beers in various stages of aging. And it's easy to see why the barrel corner is a fun place to be. Within a few minutes, Hilliard is using a screwdriver to release a saison from a chardonnay barrel. Next, a doppelbock from a massive old sherry barrel that, after spending hundreds of years in a cave in Spain, had turned from brown to a beautiful matte charcoal. The barrels, it turns out, came via Westland Distillery. "They said, 'Hey, we're going to Spain and we're gonna pick up a lot of sherry barrels,'" says Hilliard. "I said, 'Put some on the boat for us!'"

Hilliard pulls out a stepladder for me to climb up on and lets me peek through a barrel's bung at the pellicle, a thin layer of organic matter (picture a kombucha scoby or a vinegar mother, only bubblier) that provides a natural barrier between the beer and oxygen. It's thrilling.

Another project at Hilliard's involves using 18 bourbon barrels obtained from Ben Capdevielle at Captive Spirits. Capdevielle got the once-used bourbon barrels from Heaven Hill Distilleries in Kentucky, then filled them with his Big Gin. After six months of aging, the clear spirit is given a light golden color and a woody spice. It then becomes Captive Spirits' Bourbon Barreled Big Gin, which recently won best contemporary gin at the International Wine and Spirits Competition, the first American gin to do so.

"Now we're doing Belgian beer in them," says Garrett. "There's different stuff in each barrel—our saison, dark saison, and farmhouse ale. Eventually, they'll all get blended together." Depending on what that mixture tastes like, it may or may not get blended with a base beer to mellow out the flavor.

When I ask what the result will be, Garret puts his arms out, grins, and answers, "The Suffering Bastard. This is round two."

Demand for used whiskey barrels in the Pacific Northwest—and around the country—is growing; in fact, it now exceeds supply. Capdevielle said the price he pays for used bourbon barrels has almost doubled since he started doing business, something that head brewer James McDermet of Fremont Brewing (1050 N 34th St, 420-2407) echoed. McDermet said that after several consecutive years of doubling the annual production of their highly popular Bourbon Barrel Abominable (their winter warmer ale aged for nine months to a year in used Heaven Hill barrels), he purposely decided to stall growth in anticipation of the limited availability of used bourbon barrels. He called the market for acquiring barrels "competitive."

In fact, says McDermet, "Some of the brokers we originally bought the used barrels from are actually contacting us, wanting to buy them back to resell."

One of Fremont's solutions? Buying barrels from Westland Distillery, which is already moving barrels on to their South Seattle neighbors Epic Ales, Two Beers, Georgetown, and Elliott Bay Brewing.

The irony of all this, of course, is that barrel-aging is nothing new. For centuries, beer was fermented, aged, and transported in barrels. And making wooden vessels is a very old art. Until relatively recently, coopers had been doing this for centuries, crafting containers that could be used forever.

There's a good reason why distillers and brewers have rediscovered barrels. In addition to the continued growth of the craft distillery and brewery industry in general, there's also the broad acknowledgment of the intensity of flavor that barrel-aging produces. Hofmann says that barrels that have already been through two cycles of multiyear aging still give off "way too much oak." The wood in those hundred-plus-year-old Spanish barrels in Hilliard's is still bleeding the sweet, rich flavors of sherry into the beer. And over in Fremont, says McDermet, a few barrels from the late 1970s gave their beer "an entirely different character than we expected—more intense in alcohol, but in a really strange way—peaty and wood-smoked."

Even after so many years and so many miles traveled, the barrels—imbued with layer upon layer of microbes, history, and flavor—still have much to offer. Though cut from trees long ago, they remain living things.

Where to Find Barrel-Aged Beer

By nature, barrel-aged beers have limited availability, but many craft breweries in town almost always have something hanging out in a barrel that they are ready to tap. Here are a few places to look for barrel-aged brews:

Elliott Bay Brewing

4720 California Ave SW, 932-8695

Epic Ales

3201 First Ave S, Ste 104, 351-3637

Fremont Brewing Company

1050 N 34th St, 420-2407

Hilliard's Beer

1550 NW 49th St, 257-4486

Holy Mountain Brewing

1421 Elliott Ave W

Spinnaker Bay Brewing

5718 Rainier Ave S, 725-2337

Reuben's Brews

1406 NW 53rd St, 784-2859

Schooner Exact Brewing Company

3901 First Ave S, 432-9734

Stoup Brewing

1108 NW 52nd St, 457-5524

Two Beers Brewing

4700 Ohio Ave S, 762-0490