With a plethora of categories to choose from, plus a number of finishing techniques that can impart any number of flavors on aging distillates, the whiskey category truly has something for everyone. Barrel aging is one of the best ways to impart distinctive flavors to a spirit, and sherry barrels are becoming increasingly popular vessels for maturation. Whiskeys aged in sherry barrels have even spawned a unique name to describe them: sherry bombs. To learn more about the term and the spirits it describes, VinePair caught up with whiskey pro Mike Vacheresse of Travel Bar Brooklyn.

“Traditionally, the term ‘sherry bomb’ has been used to describe whiskeys that are 100 percent aged in 100 percent sherry barrels,” Vacheresse explains. “Nowadays, there is such an influx of whiskey from all over the world that if you’re confronted with a whiskey aged for four years but only two of which happened in sherry barrels, it’s probably taken on enough of the sherry flavor that it could be considered a sherry bomb.”

While he’s never conducted a deep dive into the etymology of the term, Vacheresse’s best guess is that it originated offhand after a distiller tasted a sherried whiskey for the first time. “It is a recent term,” he says. “It may have been first used subconsciously when describing a sherry-heavy whiskey due to the popularity of the term ‘peat monster’ as a descriptor for Scotch. Sherry bomb was probably used as an adjacent term, and it just stuck.” Although the term was only recently popularized, aging whiskey in sherry barrels isn’t a new practice. Scotch has been aged in sherry barrels for so long, Vacheresse says he would be surprised if a Scottish distiller used the phrase. “I think of ‘sherry bomb’ definitely as more of a new American term,” he says.

Get the latest in beer, wine, and cocktail culture sent straight to your inbox.

No matter what type of barrel a whiskey is aged in, it’s going to take on some of the flavors from the wood itself. During the maturation process, whiskey travels in and out of barrel staves, soaking in flavors from the wood. “If a whiskey is aged for 10 years, it’s going to go through this process for 10 seasons, continuously taking on more and more of the flavor from the barrel itself,” Vacheresse says. The reason why sherry bombs take on so much more flavor compared to whiskeys aged in other types of barrels is mostly due to the fact that they are aged with remnants of sherry still in the barrel.

“There is sherry left in the barrel when sherry bombs are left to age, plus there’s about six liters in the wood itself,” Vacheresse explains. “If you put clear liquid in a barrel with sherry for even just one day, it’s going to take on some of the flavor and color. The longer the whiskey is left in the barrel to age, the longer it’s going to take on the flavors of the sherry, including spices, decadent fruit flavors, and dark chocolate notes.”

For Vacheresse, the key to a well-executed sherry bomb is balance — maintaining a semblance of the spirit’s original character, he says, is key. The ideal sherry bomb has notes of sherry layered on top of the whiskey’s original flavor profile. “Distillers have to ensure that their original whiskey is still able to be detected. If they’re known for lighter, fruitier whiskeys or even a peated whiskey, they have to maintain that spirit’s essence or you may as well be drinking anyone’s whiskey,” he says. “Glendronach 15 and the Glenlivet Nadurra Oloroso are two really good examples of fine sherry bombs.”

When it comes to enjoying a sherry bomb, Vacheresse suggests that newbies work their way up. He recommends that first-timers taste a whiskey that has simply been finished in a sherry cask before trying one that’s aged in one for a few years, and then finishing with a whiskey that’s a true sherry bomb. His most vital piece of advice for drinking these whiskeys? Taste them first in their true form before adding rocks, sprinkling in drops of water, or mixing into cocktails.

“Distillers pour their heart and soul into each bottle of whiskey they produce, and it’s important to try it before altering the spirit in any way,” he says. “It’s like salting a steak before trying it first — it’s just not right.”