Whisky Buzzwords: What is Cask Strength?

Maker’s Mark Master Distiller Greg Davis explains what exactly it is.

Christopher Osburnby Christopher Osburn

When whisky is made, it’s stored in casks, or barrels, for many years and as it matures, water and alcohol evaporate out of the barrels and the proof of the whisky typically increases. “Cask strength, or barrel proof, refers to whisky’s (or any spirit aged in cask) alcohol-by-volume (ABV) straight from the cask it is matured in, which typically has an alcohol content that ranges from 55-65%,” says Maker’s Mark Master Distiller Greg Davis. “This proof can change based on the angel’s share – the amount of alcohol which evaporates from the cask per year, which really depends on environmental temperatures and humidity; the hotter it is, the larger the angel’s share.”

Cask strength is the spirit in its purest form, straight from the barrel, uncut and unaltered “What could be bad about that?” says Davis. Most bottled whisky is filtered and diluted with water to bring down the ABV to standard bottling levels, but cask strength spirits haven’t been altered in any way following maturation in the barrel. 

A recent revival in taste and the desire for a whisky that’s more flavorful is what has led distilleries to offer cask strength whiskies. Cask strength whisky is nothing “new,” but for quite some time it wasn’t what consumers looked for in a whisky (preferring a softer, more drinkable base). “At the Distillery, we’ve always shared a bit of our Cask Strength with the bartender community and they raved about how well it held up in craft cocktails without getting lost or muted by other ingredients.” He adds, “The proof is in the pudding…or the whisky for that matter.”

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In the simplest terms, Maker’s Mark Cask Strength is Maker’s Mark straight from the barrel. “What makes it real special is that the bourbon retains the essence of original Maker’s Mark, Bill, Sr., created over sixty years ago with even more front-of-the-palate flavors, in fact, it’s a very palate coating experience.” Maker’s Mark Cask Strength has a lower proof than most cask strength whiskies. “We have always entered our bourbon at one of the lowest proofs in the famed Bourbon Industry, because we wanted to be sure you still got to taste those yummy oak, vanilla and caramel flavors in balance of with the distilled spirit that Maker’s Mark fans have come to know and love – just kicked up a bit.” They are able to achieve that flavor in a few ways: Maker’s Mark goes into barrels at a consistent entry proof of 110, seasoning their barrels for 9-12 months, which breaks down the wood and delivers a more approachable flavor, and also, through using a #3 barrel char their Cask Strength showcases everything that is great about wood.

Maker’s Mark Cask Strength (available nationally in the next few months) is 110-115 proof. “Making bourbon by hand isn’t an exact science, and as mentioned earlier the angel’s share plays a role into the final proof.” Kentucky’s seasonal temperatures can fluctuate wildly – so the rate at which their bourbon becomes the “angel’s share” also differs. “We’re never 100% sure what the proof will be until we open the barrels.”

Davis doesn’t want drinkers to be afraid to try it. “For folks that are a bit unsure of how to approach barrel proof whiskies, try it with an ice-cube or a splash of water. It’s also delicious in an Old Fashioned.”