For centuries, sherry casks were the first choice of many whiskey and rum producers to age and transport their spirits. This fortified wine from Spain was incredibly popular in the United Kingdom and its colonies, so the barrels used to ship the liquid were inexpensive and abundant at every port in the empire’s domain.
For various reasons, though, the ubiquitous sherry cask fell out of favor, replaced by the markedly different used bourbon cask. In recent decades, however, distillers in both the Old World and the New have sought the rich and unique flavor of wine-finished spirits. Today, rather than using wine and sherry casks for reduced shipping costs, distillers are seeking them out with a nose for new and exciting flavors.
From Sherry to Bourbon
Visit a sherry bodega in Spain today, and you’ll likely see huge casks stacked along the floor to form the famous solera systems. These casks stay in place for decades—centuries, even—without being moved. Instead, the bodegas transfer the wine in and out without dumping the massive vessels.
Those stationary solera casks aren’t the barrels that were once common in Scotch production. Instead, the winemakers used smaller barrels to move liquid from one place to another. While those “transport casks” did pick up some sherry flavor, they weren’t the older casks deeply infused with the dark fruit and tannic notes that many distillers prize today. So, the contemporary use of sherry casks isn’t so much a return to tradition as it is a new way to achieve exciting flavors in spirits.
The use of sherry transport casks fell off for several reasons. One is the diseases and pests that afflicted the European wine industry in the late 19th and early 20th centuries. Sherry also fell out of fashion in favor of spirits, and the Spanish adopted a law that required all sherry to be bottled in Spain. Even before that final nail in the coffin, however, distillers in Britain and around the world were already using another kind of used cask: bourbon.
Wine Not?
When bourbon production exploded after the end of Prohibition, American distillers flooded the used-barrel market with inexpensive casks that they could use only once. That market remains saturated with relatively cheap barrels.
So, why would a distiller switch to a more expensive vessel that’s harder to acquire?
The short answer: flavor. Sherry, port, and wine casks bring a variety of rich fruit notes, tannins, sweetness, nuttiness, and sometimes funk. Aside from these concrete tasting notes, many distillers and aficionados speak of sherry casks as contributing depth, structure, or even mystery. That may have something to do with the fact that many people view whiskeys associated with sherry, such as Dalmore or Macallan, as high-end and decadent.
Besides these storied distilleries associated with sherry, many producers both old and new use sherry, port, and nonfortified wine casks. Most of these distilleries tend to age their spirits in a different kind of cask first, only transferring to sherry or wine casks for a secondary or “finishing” maturation. One producer that helped pioneer the practice of sherry- and port-cask finishing was Glenmorangie.
“Using a port cask to mature whisky, sure that happened,” says Dan Crowell, national brand ambassador for Glenmorangie, “But using a port cask consciously as a second maturation, we were the first to do that.”
Like many other producers in Scotland, the distillers at Glenmorangie usually age their spirits in less impactful used American whiskey barrels. “The knee-jerk cask that the preponderance of our new make would go into would be first- and second-fill ex-bourbon,” Crowell says.
Part of the reason for this practice is that using sherry and wine casks for the entirety of maturation can produce overwhelming flavors or result in an imbalanced spirit. Using two casks during the aging process also helps build complexity. Bourbon casks will bring vanilla, brown sugar, and spice notes that can potentially pair well with the fruit and tannins of sherry. Still, it can be a delicate balancing act.
Cask-and-Spirit Compatibility
One way to prevent these conflicting or disjointed flavors is to match finishing casks with the appropriate spirit.
Many experts argue that only certain whiskeys benefit from the introduction of sherry. “It’s not just that Glenfarclas can cope with sherry casks—it needs sherry casks,” says writer Dave Broom, referring to the distillery well known for its sherry cask–matured single-malt.
What exactly certain spirits possess that makes them right for sherry is up for debate, but many whiskey enthusiasts use words such as “oily,” “malty,” “weighty,” or “viscous.” Some distillers point to flavors already present in their spirits that match notes they expect from wine or sherry casks.
“We’re not trying to flavor the whiskey,” says Clear Creek master distiller Caitlin Bartlemay of McCarthy’s Oregon Single Malt. “We’re just trying to use those finishes to enhance and bring to the surface and make more accessible flavors and aromas that are already within that whiskey.”
However, predicting exactly how a wine cask will impact a spirit can be a challenge. Sherry and port are broad categories with hundreds of producers across vast regions of Spain. They vary widely in flavor and quality, and even casks from a single producer can have significant variability.
When picking out cabernet casks for Jefferson’s Bourbon, founder Trey Zoeller traversed Napa Valley to secure the casks. After the whiskey was finished, “the cab finishes were as different as the wines,” Zoeller says. Still, the notes were similar enough that the exercise wasn’t completely speculative.
One technique some distillers use to predict flavor outcomes is to add a few drops of wine or sherry to the spirit in question, or to pour the spirit into a recently drained glass—not an exact science, certainly, but enough to give a general idea of how a spirit-and-cask combo will work.
While a flavor combination may work in theory, there is a risk of pulling too much of those wine notes into a rum or whiskey. Sherry and wine casks—especially on their first use—can sometimes overwhelm a spirit with their powerful flavors, which is a problem if the goal is just to enhance the qualities of the existing spirit.
Some distillers manage that problem by blending first-, second-, and even third-fill wine casks to produce a more balanced spirit. Some blend finished casks with other original casks to subdue strong wine and sherry flavors. All of this depends on the goal of the distiller and how much nuance they want to give to the product.
At Glenmorangie, Crowell says that Bill Lumsden, their head of distilling and whiskey creation, would say that if the added finishing notes are obvious, “then he’s probably not doing his job.”
Costs and Sourcing
Another challenge is the cost of a quality sherry cask, which can easily be four or five times that of a used bourbon barrel—and even when a distiller is ready to pay it, there are often no available casks.
To address that issue, some distillers are simply making their own wine casks. That’s exactly what Glenmorangie’s Lumsden did when he had trouble finding Madeira casks.
“Bill felt somewhat helpless in the face of trying to secure a consistent, high-quality supply of Madeira casks,” Crowell says, “so he had casks built in his specs, shipped to a single Madeira producer who put malmsey into new oak, stored [the casks] in the upper tiers of their rick houses for three years, and then dumped and rush-shipped to us.”
That method, often called “seasoning” casks, may seem like a lot of trouble for a quality wine cask, but it has its advantages. For one thing, it ensures a steady supply of casks. It also allows the distiller to acquire exactly what they’re looking for.
“We controlled everything—the quality of the wine, the quality of the cask, the placement of the cask, and the madeira characteristics,” Crowell says of Glenmorangie’s madeira project.
That’s why many distilleries—especially those in need a large, consistent supply of wine casks—opt for the seasoning method. Macallan and Highland Park are two other Scottish distilleries that have worked out such deals with Spanish sherry producers.
For distillers without such large demand, there are companies that import large numbers of sherry and port casks and then sell them in smaller quantities—often much easier for distillers than working out individual deals with sherry producers and shipping a few at a time.
“We are working with Casknolia in Spain,” says Bartlemay at Clear Creek. “They’re actually working with Kelvin Cooperage and are importing whole containers [of casks] to the Bay Area from Spain, and then parting them out to distilleries as they need them.”
Telling the Story
While there’s an abundance of different types of wine casks available to distillers today, they come with one last challenge: educating consumers. Tell a whiskey drinker that a spirit was finished in “sherry” or “port” casks, and they’ll have some idea what flavors they ought to expect.
Among more knowledgeable consumers, names such as Oloroso and Pedro Ximénez have some meaning—but once a distiller starts talking about vino de color or tokaji, there may be a bit of a barrier. That may not be a problem for well-established distilleries already known for unique finishes, but it can pose a challenge for craft distillers already working uphill to explain an unusual or less well-established spirit.
“When it comes to the American single-malt category, there’s still a lot of consumer education that we’re doing,” Clear Creek’s Bartlemay says. “So, one must be careful when making the decisions on finishing casks and not [add] too many more layers of education to what it takes to have a consumer pick that bottle up on the shelf.”
That’s one reason smaller distillers may opt for more better-known casks. “When you’re choosing to do a sherry-cask finish on an American single-malt,” Bartlemay says, “choosing a sherry finish that already has a little bit of recognition within the culture reduces the threshold of education to a consumer.”
Still, there are a growing number of knowledgeable consumers thirsty for new flavors. Maturing spirits in sherry casks—while not quite a return to tradition—is an exciting way to quench that thirst. Add the vast number of unique wine casks available, and there’s fertile ground for craft distillers to explore.