Cask Strength Whiskey: Why High Proof Is So Hot Right Now

Like their craft beer counterparts, North American Whiskey producers seem hell-bent on putting out increasingly hot whiskies. We’re talking about liquid nuclear fusion similar to the surface of the sun! These days many whisky enthusiasts are on the prowl for cask-strength whiskies well over 100 proof. 

Whales like Stagg Jr. and George T. Stagg Bourbon are consistently flirting 140 proof. While classics like Elijah Craig Barrel Proof and Wild Turkey Rare Rare Bourbon breed are becoming everyday favorites at 60% ABV and higher.

What’s it all mean? Well, if you’re unfamiliar with cask-strength whiskey then you’ve come to the right place.

What is Cask Strength Whiskey?

Cask strength typically infers that a particular whiskey bottling has not been diluted with water once the spirit has been emptied from the wood. While the idea of dilution may seem alarming at first glance, it’s important to remember that adding water at bottling is part of the traditional whiskey production process. It’s the final act that brings a level of drinkability to a dram. 

When it comes to bourbon, rye, and other whiskies, these spirits will not be diluted to below 40% ABV or 80 proof. When we talk about cask-strength whiskey or barrel-proof whiskey, we are expecting anything bottlings at least 100 proof if not much higher.

What Exactly Happens in a Whiskey Cask?

A lot of science comes into play during the whiskey maturation process. Aging whiskey may end up with higher or lower alcohol content over time. During maturation, the distillate evaporates through the wood in what’s known as the “angel’s share.” This can account for a loss of up to 5% of a producer’s stock every year

The proportion of ethanol lost to water lost is affected by many variables. Things like temperature, ambient climate conditions, and barrel types can all affect the spirit as it ages. 

For example, in Scotland, a cool climate and used barrels mean that most cask-strength whiskies finish at or below their initial entry proof. Whereas a Kentucky Bourbon experiences wide changes in ambient temperatures and humidity in new oak barrels—the alcohol content rises during aging.

Legal Definitions for Cask Strength

When you see some marketing or a piece of packaging that says “Cask Strength” you may not know what you’re getting. Different regions of the world have varied regulations regarding whiskey.

UK

Scotch whisky is one of the better-protected spirits in the world (as it should be). As expected, the UK government tightly defines the use of terms such as “Blended Scotch Whisky” and “Single Malt Scotch Whisky.” The same government body has laid no such definition for “cask-strength whisky.”

However, the Scottish Whisky Association (SWA) advises that “the alcoholic strength of [cask strength whisky] must not be adjusted after maturation.” 

US

In the US, the Alcohol, Tobacco, and Firearms Bureau (ATF) governs all things deemed harmful. This includes regulation of beautiful copper and red-amber liquid gold that we all treasure.

ATF Ruling 79-9 outlines that whiskey can only be called “Original Barrel Proof” and “Barrel Proof” if the bottling is no lower than 2 degrees of proof lower than when the barrels were emptied during the aging period. Included in this ruling were also the terms “original proof”, “original barrel proof”, and “entry proof.”

This leaves terms like “cask strength” and “barrel strength” open to creative interpretations. In other words, it’s the wild west for bourbon and American single malt whiskey.

Why Drink High-Proof Whiskey?

Okay, so all of your friends are raging about 50 percent this and 65 percent that. Has this become the new lifted truck or Cadillac Escalade? It’s not the size of—we digress but you didn’t get into whiskey solely to impress others!

It’s about scratching that itch. Buying, collecting, and enjoying rare whiskies is about getting the best bottles for you. So what godforsaken reasons would you want to tuck into nostril-singeing and throat-scalding barrel-proof whiskies?

Bigger and Varied Flavors

When it comes to vanillins, tannins, esters, and other compounds, it’s not always the case that bigger is better. However, a cask-strength bourbon will be packed more densely with not only ethanol but loads of caramel, baking spices, and fruity notes that many of us pine for.

After drinking cask strength version of old favorites, tasting the original will often feel like drinking in black and white.

Non-chill Filtered

Whiskies 46% ABV and higher are not normally chill-filtered. What does that mean? Well, at a minimum, it means oils that cause chill haze are not removed from the spirit. This gives big bourbons and single malt whiskies the big oily feel that many prefer. 

Romance of the Dram

We all enjoy whisky for different reasons. We’d be remiss if we didn’t admit that we’re always a sucker for a good story. When you pour a couple of fingers of Laphroaig 10 Year Old, you can’t help but translocate mentally to the shores of Islay smelling the salty, peaty air. 

Or maybe you crack open a bottle of Jefferson’s 25 Year Old Bourbon and think about the lives that have come and gone since the whiskey was first put into wood. 

Barrel strength and original proof whiskies give us a taste of the artisans' handiwork. It’s like taking a peek into the maker’s workshop. We get to taste the whiskey in the same form as distillers and blenders would while working with the final product. 

It's Personal

Cask-strength whiskey means you get the spirit in its purest form. Since it hasn’t been watered down by the distillers at bottling, you can customize every pour to suit your tastes. If you prefer a dram on steroids, add little or no water. If you prefer to stay on two feet for the evening, then you can bring things closer to a regular bottling strength of around 40-43%.

Either way, it’s up to you to decide.

Value

While most of us aren’t necessarily looking for the cheapest whiskeys, we are looking for good value. That may be winning an auction below market rate for a bottle of Old Rip Van Winkle or finding a case deal on some Micther’s Straight Kentucky Bourbon. 

Cask-strength whiskies have more spirit (and less water) in the same size vessel as the diluted stuff. With original-proof whiskey, you are often getting more for your money—especially if you like to add a substantial amount of water to your glass!

Argument Against Cask Strength and Barrel Proof Whiskey

At this point, you might be thinking, what’s the point of drinking non-cask strength whiskey anymore?

Well, the devil’s advocate in this conversation would point out that the dilution process at bottling is part of traditional whisky making. By removing this essential step, you are creating a new type of product that is different from proud spirits like American bourbon and Canadian rye. 

Now that the whiskey devil has your ear, they add that the master blenders are diluting the to enhance bottlings and give them a better balance. Adding water helps flavors and aromas shine through as intended.

Lastly, when you add your own water, you are adding all sorts of trace minerals and ions that can alter the perceived taste of a whiskey. (That is unless you can access the same water as the distillery). Even if you opt for deionized water, you will be altering the water chemistry.

Keeping all those points in mind we have a simple solution to the cask strength versus bottling strength argument: buy and drink both types of whisky!

A Few of Our Favorite Cask Strength Whiskies and Barrel Proof Bourbons Today

Stagg Jr. Barrel Proof Bourbon

We can discuss cask strength whisky without talking about Stagg Jr. As you may know, every batch of George T. Stagg’s younger brother is made from a combination of bourbons aged around 8-9 years. Every batch is unique but lives up to the Stagg legend and is bottled in the ballpark of 130 proof.

Booker’s Small Batch Collection 2022-02 “The Lumberyard Batch”

Part of Beam Suntory, Booker’s is no newcomer to the world of cask strength bourbons and rye whiskies. Every limited release is made uncut, unfiltered, and blended from a hand-selected barrel. 

The Lumberyard Batch is made up of bourbon aged just over 7 years and packed with cinnamon, vanilla, honey, and plenty of spice (13% rye in the mash bill). This barrel strength offering from Booker's soars above many other batches and weighs in at 124.8 proof. 

Michter’s US-1 Limited Release Barrel Strength Rye

Michter’s dabbles in the realm of high-proof whiskey but usually tends towards balance. This limited-release rye is based on an undisclosed grain bill but is full of hot cinnamon spice and rich vanilla. 

The rye whiskey enters the casks at 103 proof. Thanks to the magic of Michter’s aging environment, the final product is bottled at 110.4 proof (55.2% ABV).