If you analyze what makes bourbon taste so good, you might think of the sweetness that comes from its corn mash, or the caramel and vanilla that come from the charred barrels when it ages.

But there’s another, almost invisible influence that makes whiskey what it is: the air that it breathes.

John Rempe, Lux Row’s Master Distiller, says that the environment where the barrels are stored has a surprising impact, even from one barrel to the next.

Barrel storage
There are three types of barrel storage:

• Dunnage is the traditional method used in Scotland. Barrels are stacked on their sides in a cave-like building, fashioned from natural materials such as earth and stone.
• Rickhouses are multistory buildings, anywhere from three to nine stories tall, with racks (or “ricks”) where barrels are stacked on their sides.
• Palletized warehouses place the barrels on wooden pallets, where they sit upright. They’re stacked more tightly and can accommodate a larger number of barrels in the same space.

All three methods have their fans, Rempe says. But Lux Row uses rickhouses.

“Rickhouses are the traditional American whiskey style of aging,” he says. “It makes room for a lot of barrels, but the design lets you maximize air flow.”

Air flow is everything.
“Whiskey in the barrel needs air circulation to drive the shifts in temperature,” he says. “Whiskey expands with heat and contracts when it gets cold. Having it soak in and out of the wood is essential to the maturation process, and good air circulation helps drive those temperature fluctuations.”

Those fluctuations help American whiskey, and bourbon in particular, to age more quickly than Scotch.

“The climate in Scotland doesn’t have the major temperature fluctuations you see in Kentucky, where it can get below 0 and above 100,” Rempe says.

In a rickhouse, there are even fluctuations between barrels in the same building.

“The temperature in the bottom of a rickhouse is cooler, like a basement, while the barrels on the top floor are warmer and surrounded by dryer air,” he says.

Amazingly, this affects how quickly the whiskey inside those barrels mature.

“Even with whiskey that’s distilled on the same day, there’s a huge difference between barrels on top versus the barrels on the bottom,” he says. “You get a completely different whiskey.”

When whiskey is aged in a warmer and dryer environment, it loses more water to evaporation, and the alcohol strength, or “proof,” will rise.

“If we put the whiskey into the barrel at 125 proof, over eight years of aging, it can go up to 130 or 132 proof,” Rempe says. “That higher alcohol concentration is extracting more soluble components from the barrel and getting a deeper color [and] stronger flavor.”

“Down at the bottom, it’s cooler and more damp, and more water remains in the barrel,” he says. “The proof in those bottom barrels can drop down to 121 proof. There’ll still be a generous amount of alcohol, but the composition will be a little different: It’ll be lighter in color [and] in flavor.”

Having a range gives him a wide variety of flavor profiles from which to choose. He’ll use different blends depending on what is being bottled.

“When I’m pulling barrels for different brands, I might choose a higher proof barrel from the top for one, while for another, I would pull selections from the top, middle, and bottom to get a good representation of the entire warehouse,” he says.

Lux Row currently has three rickhouses, each six stories tall: six floors, with three barrel tiers per floor, 18 barrels stacked up — and there’s another on the way.

“We’re building a fourth that’ll be finished within the next month — just like the others, it’ll be your classic Kentucky bourbon rickhouse,” he says.