When you think of a whiskey barrel, you probably imagine its outer appearance – the oak staves and metal hoops. But the inside of the barrel is where the magic happens. Barrels aren’t just for storage; they play a key role in aging. The choices each distiller makes about the barrel ultimately shape the profile of the finished product, as aging whiskey is all about how it interacts with the wood over time.

In the world of whiskey, people often use “barrel” and “cask” interchangeably, but there’s a subtle distinction between them. A barrel is a specific type of cask primarily used for aging whiskey, while the term “cask” is a more general one that covers various containers used for aging and storing all types of alcohol. In this blog post, we’ll explore the behind-the-scenes decisions that shape the perfect flavor profile during aging. Most whiskey barrels, or casks, are crafted from American White oak or European oak. Oak is ideal for aging because it’s porous, letting whiskey interact with the wood, giving the spirit its unique flavor, color, and aroma.


Before adding the whiskey to each barrel, we need to ‘char’ or ‘toast’ the inside of the wood. This involves exposing the inside of the barrel to fire, either by burning it (charring) or heating it gently (toasting).

Charring and toasting make the inside of the barrel consistent from batch to batch and help act as a natural filter, refining the spirit by removing impurities. This process also adds additional flavors and aromas that would otherwise not come from the oak alone, such as spice and smoky notes.


One of the most important decisions in whiskey production is choosing the size of the cask for aging your spirit. The whiskey industry uses various cask sizes, and each size affects the aging process and flavor profile differently. Smaller casks have a higher surface area-to-volume ratio. This expedites the interaction between whiskey and wood, resulting in faster flavor extraction and a bolder character in a shorter time. Larger casks offer a more gradual maturation process. This allows the spirit to mellow and develop subtler, more nuanced flavors over an extended period.


While in the barrel, factors like climate, temperature, and humidity impact aging.

In warmer places like Kentucky, the barrel expands and contracts due to temperature changes throughout the day. This causes the liquid to move in and out of the wood more rapidly, strengthening the flavor.

Whereas, in colder climates, like Scotland or England, with more consistent day-to-night temperatures, whiskey (or should we say whisky!) matures more slowly, creating more subtle wood flavors.

Other factors that can shape the flavor during aging are different humidity levels, which affect the amount of evaporation within the barrel (known as the “angel’s share”) and can concentrate flavors over time, as well as the aging environment, also known as terroir, which can add its own flavor elements. Whiskey aged by the coast often takes on salty and briny notes, while whiskey aged in high-altitude or mountainous regions can have more floral and mineral notes.

In the case of BLACKENED Whiskey, exposing the liquid to low-frequency sound waves, which we call sonic enhancement, or BLACK NOISE, can accelerate the interaction between the whiskey and the wood, extracting more flavor.


When you listen to a loud bass, you can feel the vibration or movement in your body. Similarly, low-frequency sound waves can make the liquid move inside the barrel. Imagine a filled barrel in a warehouse, placed on the rick, and left for several years – undisturbed and still. Now imagine taking one of those barrels and exposing it to movement instead. This is what we do during our sonic-enhancement process.

Each batch of BLACKENED plays a unique batch playlist of Metallica’s music, which, in turn, forces a deeper interaction between the liquid and the barrel and turns up the volume dial on the intensity of flavor.


Talking about ‘finishing’ whiskey means transferring it to a different barrel to add another dimension to the aging process. Typically, this new barrel has previously contained a different type of alcohol, such as sherry, port, or wine. This change allows the spirit to absorb more unique flavors and characteristics left behind in the wood from the previous contents.

Regarding BLACKENED, our flagship edition is finished in Brandy casks, which adds notes of apricot to the liquid, playing perfectly alongside the honey and caramel notes of the blend. However, we also deploy distinct finishing techniques in our Masters of Whiskey Series. The first, a collaboration with Willett Distillery’s Master Distiller, sees a straight rye whiskey finished in Madeira casks, resulting in a spirit that boasts buttery caramel, earthy mint and fresh cut hay flavors on the palate, and cinnamon butter & dark walnut on the finish.

The second, a collaboration with Angel’s Envy Co-Founder Wes Henderson, created a Kentucky straight bourbon finished in white Port wine casks. This finish resulted in an abundance of pear & raisin on the nose and more pear, honey, chipotle cinnamon & walnut on the palate.

Our newest MOW collaboration, with Rabbit Hole Distillery’s Founder & Hall of Fame whiskey maker, Kaveh Zamanian, sees a bourbon whiskey blend finished in Calvados apple brandy casks. This created a layered and complex liquid with apple butter, rhubarb, honeysuckle, graham cracker, and macadamia nut on the nose and smoky campfire & field clover notes on the palate.

So, as you can see, in the world of whiskey, the barrel is not just a vessel; it’s a time-worn partner in crafting flavors. It involves the subtle distinctions between charring or toasting of the wood, the careful selection of barrel sizes, the location you store the barrels in and how you finish the aging process.

In the end, these elements, managed by the talent of distillers, each play a pivotal role in shaping the final spirit and come together to create unique symphonies of flavors and aromas that define each brand. Cheers to the barrel and all it adds.

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Owner/President at The Bourbon Flight, LLC | + posts