If you’ve ever toured a rickhouse at a Bourbon distillery, you’ve probably noticed that the barrels inside look weather-worn and rugged. It’s a stark contrast to wine cellars, where pristine barrels are usually kept in temperature-controlled conditions.
Meant to impart flavor and complexity, wine and whiskey barrels generally serve the same function. However, producers employ markedly different techniques throughout their processes.
From stave drying to toast levels and char, many factors contribute to what kind of flavor barrels impart. It’s a process coopers have refined for more than a century.
“[Barrels are] our most precious resource in terms of it’s the thing that we’re making that’s the hardest, that costs us the most and that we put the most heart and soul into,” says Pia Carusone, co-owner of Republic Restoratives distillery in Washington, D.C.
The lines between wine and whiskey barrels occasionally blur, but the distinct differences mean a great deal for your drink.
Wine and whiskey barrels have a few striking differences in appearance. Wine barrels tend to appear more polished, with a sanded exterior, fewer imperfections and corrosion-resistant galvanized steel hoops.
“You’re typically using the best of the oak [for wine],” says Chris Hansen, general manager at Seguin Moreau Cooperage in Napa, California. “You don’t want defects or a lot of discoloration because wineries want the barrels to look pristine and perfect.”
That attention to a wine barrel’s appearance doesn’t end after barrel reaches the winery.
“We like to have [the barrels] look pristine when people [come to] Napa Valley on tours, but also it’s really important for any sort of microbial [contamination],” says Shawna Miller, winemaker at Luna Vineyards in Napa Valley. Luna has about 1,000 barrels on site.
“We try to treat the winery like a surgical room,” says Miller. “If I looked down and saw a leaky barrel, I would lose it. It would be like an infected wound to me.”
Whiskey producers, by contrast, allow for slight imperfections like knot holes in staves, the wood planks that form a barrel’s sides. Though these slight imperfections may lead to occasional leaks, coopers are able to patch the barrels.
“The sugars in the whiskey allow for a more open grain without leaking,” says Tony LeBlanc, president of Silver Oak Winery, which owns The Oak Cooperage in Higbee, Missouri. “Because wine is [drier], it requires a much tighter grain with no sap, knots or [other imperfections], or it will leak.”
The Oak Cooperage makes barrels primarily for wineries, but LeBlanc says that staves that don’t make the cut for wine barrels will be repurposed for distilleries. Whiskey barrels make up about 8% of its total production.
“We literally make a wine barrel for the whiskey industry, if they’re interested in it,” says LeBlanc.
Whiskey barrels are also usually held together with dark steel hoops, which LeBlanc says is primarily an aesthetic decision by coopers.
You can find barrels of all sizes, though the standard for spirits is 53 gallons. Wine barrel sizes tend to vary based on what wine they hold. Miller uses Brittany and Bordeaux barrels primarily, which hold 59.4 and 60 gallons, respectively.
Prior to being shaped, staves must be dried to a moisture content of around 12%. This process, called seasoning, smooths out acrid, green characteristics and develops more favorable aromatics and flavors.
For wine barrels, staves are stacked outdoors on pallets to dry, often for two or more years.
“Natural seasoning and exposure to rain, [snow] and elements will wash more harsher tannins and flavors out of the wood until it reaches a moisture content that you can make a barrel [from],” says Hansen.
Staves for whiskey barrels, in contrast, are typically kiln-dried. The process takes significantly less time, which allows for more expedient barrel production.
Now, though, coopers and craft distillers are blurring this line.
“It’s much different now than it used to be because there’s many distilleries, especially the craft ones, looking for some natural seasoning of their oak, maybe six months, 12 months, 18 months,” says Hansen.
Carusone opts for natural wood seasoning for her Rodham Rye and Borough Bourbon. The barrels are sourced from Seguin Moreau.
“We don’t specify [stave seasoning] to them, but they provide a standard that we’re comfortable with,” she says. “That’s the number one reason we’re working with them. The cottage industries that have grown up around wine are very reliable, time-tested.”
Carusone says that it’s harder to find smaller, reliable cooperages that specialize in spirits barrels. They tend to work with “large, legacy distilleries in Kentucky and Tennessee, and they don’t even answer the phone from companies like ours.”
Toasting and Charring
After wood is sufficiently seasoned, the next step is to toast or char the barrel.
This step is similar to roasting marshmallows. You can brown the barrel slowly over a low-intensity fire, or set the wood ablaze and wait for the flame to fizzle out. Both have an effect on flavor, and they can be done to varying levels specified by the winery or distillery.
To slowly brown, or “toast” the wood, is the preferred method for wine barrels, often done over an oakwood fire. This technique lends a bit of golden color and allows for subtle, nuanced flavor exchange.
“We want to get all of the new flavors out of [a barrel] when they’re fresh and new and lightly toasted,” says Miller. “The first year, I would say we get 85% of [the] flavor out of them, but they will still give a little bit for the next two years. After that, we use them for neutrals and then we sell them [for reuse].”
To char a barrel involves direct contact between fire and wood, which leaves a blackened surface often sought for whiskey barrels. In fact, a new, charred American oak barrel is a legal requirement for Bourbon.
Char creates a textured surface that alters the makeup of the oak, which filters out unwanted compounds in the distillate and imparts sweet caramel and vanilla notes. The blasts of fire are achieved typically with gas, rather than a wood flame.
“[Charring] begins to break down the layers of the wood in such a way that it allows the whiskey to come into surface contact and actually sees the process of aging as temperatures rise and fall,” says Caruson. “But it also acts as a natural filtration. When you have a layer of char on the inside of the barrel, you literally have a natural filtration system with the whiskey.”
Because of the flavor intensity that charring imparts, LeBlanc says it would be “too dominant” for wine. Wineries have found this to be the case through trial and error.
“When the wine business started in the U.S., a lot of wineries wanted to use barrels from the U.S., but they didn’t have very good results [with whiskey barrels] because there’s too much char on the inside,” says Hansen. “So, they looked at how the French barrels were being made were for wine in Europe.”
Some, like The Oak Cooperage and Seguin Moreau, offer a blend of toasting and charring for whiskey barrels. LeBlanc says they’ve made standard practice of using both methods in tandem.
Hansen says the practice started to gain popularity within the last decade or so. “The two can create a little bit more complexity, smooth the tannins out a little bit, and give you a little more vanilla,” he says.
Carusone uses these barrels to age Republic Restorative’s Borough Bourbon.
“We think it adds to a faster extraction of vanillin and a deeper, richer flavor,” she says. “And this is all so dependent on time. If we had all the time in the world, we might make different decisions, but we’re a small business, so we don’t. We are looking to make terrific whiskey as fast as possible, but that doesn’t mean we’re looking to cut corners.”