I’m a sucker for wine-cask-finished whiskeys (well, just whiskeys, but sometimes I pretend to have a palate). The Glenmorangie Madeira Wood was one of my first Scotch love affairs. I recently discovered the new Basil Hayden Red Wine Cask Finish, which blends Kentucky Straight Bourbon with bourbon partially finished in red wine casks to a pretty spectacular (i.e., delicious) effect.
This led me to ponder why it is so delicious, which led me to investigate the whole finishing process. Transforming raw materials into drinkable liquor is fascinating–and a lot more complicated than the still on that old TV show M*A*S*H led me to believe (if you don’t get this reference, it’s because you aren’t quite as finely aged as I am). Many spirits are aged (also called “maturing”) to make them palatable because when a spirit is initially distilled, it’s often pretty raw stuff. Bourbon, for example, starts life as a clear liquid with none of the charm or taste notes of a good bourbon–those come from initial aging in barrels made of charred American oak (so-called white whiskey usually uses a different recipe or mash bill, because it’s not going through this process). According to Wine Magazine, barrel aging is where bourbon gets the most flavor and color.
There are some specific requirements around aging–to call a whiskey a bourbon, for example, it must be aged in oak barrels for at least two years. Scotch has to be aged at least three years in used bourbon barrels; anejo tequila between one and three years, typically in used whiskey or wine barrels; and aged rum has to have spent at least one year in a bourbon barrel somewhere.
So if so much effort goes into aging a spirit, why is finishing crucial to (some) shades?
What is finishing?
Finishing describes the process of giving a spirit a specific flavor and color profile by storing it in a vessel–commonly wood barrels that have previously matured a soul, but only sometimes. It’s a secondary aging process involving transferring the already-aged heart to a second vessel to get the desired flavor profile and color. Think of it this way: You distill something into a clear alcoholic liquid. You age that in a barrel, where it transmogrifies into whiskey. Then you age the whiskey in a second barrel that held red wine, and it turns into, say, Basil Hayden Red Wine Cask Finish.
The chemistry of maturing and aging is complex, but it boils down to three fundamental interactions:
- Subtractive: The interaction between the wood and the spirit removes unwanted or undesirable flavors.
- Additive: Time spent in the barrel pulls color and flavor notes from the vessel into the heart.
- Interactive: As the heart sits in the boat, it interacts with the vessel material (e.g., wood) and oxygen.
This is the same process in the initial maturing process, which transforms the clear distillate produced in the distillation process into what you recognize as whiskey, rum, or tequila. The finish brings in secondary flavors–for example, adding a touch of wine to a whiskey.
There’s one other aspect of finishing: Resting. Some spirits are “rested” in a “neutral” vessel made of something like stainless steel or glass. These materials don’t interact with the heart at all, so no additive or subtractive process is going on. According to Master Distiller Harlan Wheatley, this neutral resting allows a soul to settle down and mellow without adding additional flavors. Resting is familiar with white spirits like pisco or tequila, whiskey, and other spirits.
For a long time, certain spirits were never finished. According to VinePair, spirits like vodka and gin aren’t traditionally matured or finished because they contain fewer compounds that can interact with, say, a wood barrel. While vodka might be rested in a neutral vessel like a stainless steel barrel, it wouldn’t be finished in a cask. But that perception is changing–increasingly, you’ll see “barrel rested” or “barrel aged” vodkas and gins as distilleries experiment with new categories. Technically, this means those spirits are no longer legally considered vodka (which the Alcohol and Tobacco Tax and Trade Bureau [TTB] defines as “without distinctive character, aroma, taste or color”) or gin (which the TTB only recognizes in its un-aged form), but that doesn’t mean these experiments aren’t worth drinking.
Finishing comes down to engineering the final product by exposing it to specific materials and conditions over a particular period. There are several different ways to finish off a liquor. One of the most significant considerations is what the barrel holds before you put the whiskey in it. The barrel’s wood will absorb the flavor of what’s inside it, then leech that flavor back into whatever it holds next, creating a complicated history of flavors.
Here’s how some spirits are commonly finished.
Whiskey
While many spirits are finished these days, it’s widespread in the whiskey world. The most common finishing for whiskey is in wood barrels or casks, including:
- Bourbon barrels. Many whiskeys are finished in bourbon barrels because bourbon can add notes to other whiskeys they normally wouldn’t obtain from their aging process.
- Wine casks. Whiskey is frequently finished in wine barrels to pull the fruit and spice flavors from different wines into the spirit. Sherry, port, Madeira, and marsala are standard barrels–other wines are chosen based on what will complement the whiskey’s flavor profile.
- Rum barrels. If you want a sweeter whiskey flavor, you can finish it in rum casks.
Those are just the most common. You can find whiskeys finished in vermouth, maple syrup (! ), brandy, and beer barrels.
