Choosing the Right Char for Your Whiskey Barrels

Here in the good ol’ US of A, we bleed whiskey with veins gushing full of rye, wheat, and bourbon. It’s a boldly flavorful cornucopia of grain distillates, and a patchwork of production regulations governs each of them.

However, our national whiskeys share at least these four requirements:

• The maximum distillation proof is 160 (or 80 percent ABV).
• The base grain (corn for bourbon, rye for rye, etc.) must be at least 51 percent of the grist.
• The maximum barrel-entry proof is 125 (or 62.5 percent ABV).
• It must mature in new, charred oak barrels.

That last requirement merits some deeper conversation because it affords the distiller quite a bit of latitude when it comes to whiskey character.

Raise a Toast to Char

Sure, we know that whiskey barrels need to be made from oak, and 99.999 percent of the time it will be American white oak (Quercus alba). So, that part of the equation is a relatively fixed variable.

But what about the char level? All the regulations say is “charred”—so, in theory, we can get a little creative here. First, let’s talk about the charring process, what it is, and what it does to the barrel.

[PAYWALL] When it comes to making barrels for the maturation of whiskey, there are two primary types of heat treatment. For toasting, the barrel is “gently” heated over longer periods of time—20 to 60 minutes, or more—at temperatures ranging from 122°F (50°C) to 464°F (240°C). Toasting releases wood sugars from the hemicellulose and caramelizes them. It creates color compounds. It breaks down lignin into an array of aromatic awesomeness. Basically, toasting is what gives whiskey much of its flavor.

Charring, on the other hand, is literally setting the cask on fire from the inside. When that happens, it forms a layer of activated carbon. Contrary to popular belief, the charring process doesn’t create much in the way of flavor. As the wood catches fire, pyrolysis actually destroys a number of flavor compounds. That’s complicated somewhat by the fact that the charring process also contributes some toasting, forming in a gradient below the char layer.

Nonetheless, a layer of carbon formation is the primary goal of charring—and carbon doesn’t do such a great job at contributing flavor. Instead, it strips it away: The char layer does clean up the spirit over time, ridding the new-make of some of its more aggressive aromas and flavors, including sulfur and some higher alcohols.

Note that not all whiskey barrels are both toasted and charred. Some customers opt for a char-only approach, which may not be the wisest choice.

“I 100 percent recommend toasting before charring,” says Chris Nottingham, COO of the WV Great Barrel Company in Caldwell, West Virginia. “The toast allows you to get those unique flavors,” such as vanilla and caramel. Most customers “get char No. 4 only, and I think that is due to the historical norm. [With] char No. 4 only, you are limited to only the surface extraction of flavor, [whereas] with toast you break down deeper into the wood to get those strong unique flavors.”

In Hodgenville, Kentucky, ZAK Cooperage delivers a similar message to its own customers. “We absolutely recommend toasting before charring,” says customer relations specialist Jessica Ann Zimlich. “Skipping that step leaves a lot of flavor development on the table.”

How Far to Char?

Cooperages differ on their char levels and how they achieve them. As opposed to the toasting process, measured in fractions of an hour or more, charring procedures are measured in seconds.

A char No. 1 may be aflame for a mere 15 seconds, while a No. 2 may go for 30. A char No. 3 may go for only a few seconds more than a No. 2, while char No. 4 stops just a few seconds short of a full minute. However, this all varies among cooperages because their individual charring techniques vary.

For instance, WV Great Barrel Company chars their barrels anywhere from 24 seconds, for lighter chars, to nearly a minute for their heaviest. The Barrel Mill in Avon, Minnesota, uses 15 seconds for char No. 2, 45 seconds for char No. 3, 60 seconds for char No. 4, and 80 seconds for their char No. 5. ZAK Cooperage does a 15-second char No. 1, a 30-second char No. 2, a 35- to 45-second char No. 3, and a 55- to 65-second char No. 4.

I can easily recommend all three of these cooperages—and a few others to boot—but I can also say that even though they all make great barrels, their casks are not easily interchangeable because of different char and toast profiles. For example, I have some 40-gallon char No. 3 casks from the Barrel Mill in my inventory that are maturing some really beautiful rye. But when I compare them to my 53-gallon char No. 3 casks from WV, they interestingly seem to be maturing more slowly—which is a bit counterintuitive, considering the difference in internal surface area. That’s not a complaint, mind you—it’s just an observation on time. Both casks are making great whiskey, just differently.

Another example that I often recount to folks: Our friends at Watershed Distillery in Columbus, Ohio, were using char No. 4 casks exclusively from one cooperage for many years. They later accepted a better price from a different cooperage and made the switch. However, they quickly realized that the new cooperage’s char No. 4 barrels weren’t behaving the same way as the previous ones. So, they convinced the new cooperage to amp up their char to a No. 5, which more closely resembled their older barrel stocks.

The industry has long thought about various chars in fairly static terms. Briefly:

• A char No. 1 is effectively a very heavy toast.
• Char No. 2 will lend nice amounts of caramel and slight roasted flavors.
• Go a bit longer into char No. 3, and you’re really cooking with fire, adding in a little spice and a lot of roast.
• Char No. 4, aka “alligator char”—for the scaley appearance that forms on the char layer—brings slight smoke notes to the fore along with hints of tobacco.

However, the reality is more dynamic and varies from cooperage to cooperage—as does the flavor that each distillery is able to get from those barrels.

One Size Does Not Fit All

The most common char levels in American whiskey—notably bourbon—have historically been Nos. 3 and 4.

Jim Beam and Wild Turkey both use char No. 4 for most of their whiskeys. And Jim Beam—as the company will happily tell you any time you turn your head in their general direction—is the world’s best-selling bourbon. So, they’ve got to be doing something right. Right?

However, from the perspective of smaller craft producers, using the largest distillers in the world as a template for technique is always a fraught proposition. Don’t get me wrong: There’s a lot to be said for the things that distilleries such as Beam and Turkey do. They make a lot of great products and have found ways to do them well… for them. In other words, not everything those companies do will work equally well—or at all—for a small distiller. (And vice versa.)

I’m reminded of the now-famous “experiment” that Buffalo Trace did many years back, when they put their bourbon distillate in a variety of cask sizes ranging from five gallons to the standard 53-gallon barrel, then matured everything for about five years. When it was all said and done, they proudly proclaimed that small barrels made inferior whiskey.

Putting aside the fact that their experimental design wouldn’t have passed muster in a fifth-grade science class, all they could reasonably conclude at the end of the whole affair was that small barrels made inferior whiskey for them. There were loads of other distillers using small casks at the time of the Buffalo Trace press release—and a few were scoring just as well or better than Buffalo Trace in tasting panels and trade magazines. (They include the distillery I worked for at the time.) This is all to say: Unless you are Buffalo Trace, Beam, or whoever, you shouldn’t necessarily worry about what they’re doing or saying about how to “properly” make whiskey. Trust me: There are a lot of ways to make great whiskey.

Which brings us back to the question at hand: Should you opt for a high char simply because that’s what the big guys use? The answer to that question is a lot more nuanced than most would be willing to admit.

The Barrel as an Ingredient

One of the newer whiskey distilleries making waves out in the market is Hard Truth from Nashville, Indiana. I’ve had several of their whiskeys over the past few years and have been fortunate to get a deep-dive, behind-the-scenes tour of the distillery and campus. They make some fantastic liquid—and they’re using exclusively char No. 1 casks with a heavy toast. How’s that for a hot take on the topic?

Hard Truth master distiller Bryan Smith says that when they first got started, they were using a mix of char No. 2 and 4; they later landed on the “interesting choice” of char No. 1 based on guidance from their friends at ISC Barrels in Lebanon, Kentucky.

“Through the lens of time, it’s clear that for our particular new-make distillate, a char 1 barrel with a complex toast rounds out our flavor profile nicely,” Smith says. “Through lots of R&D with ISC—and because we exclusively produce sweet mash—the clean, fruit-forward, sweet distillate we produce didn’t require much subtraction from a heavy barrel char. By not burning away more layers of wood, we are able to save most of those complex, toasted sugars for our whiskey.”

I really dig what Bryan is saying there because it jibes with my own whiskey-making ethos quite a bit. They are treating the barrel as an ingredient, not just a tool or a means to an end. By using low-char barrels that have a mix of toast profiles, they have paired the flavors from their new-make to the barrel chemistry on offer. It’s a more holistic approach than the one-size-fits-all attitude of the larger houses.

There are other factors you should also consider when deciding on the perfect char for your whiskey. In no particular order—and certainly not exhaustive—here are some things I think about for my own programs:

• planned or estimated maturation period
• warehouse macro- and microclimate
• rack level and barrel location in the warehouse
• barrel size
• target profile of the finished spirit
• profile of the new-make spirit

ZAK’s Jessica Ann Zimlich says she adds a few more variables to the mix when she speaks with customers. “We don’t take a one-size-fits-all approach,” she says. “Our recommendations always depend on the distillery’s goals and environment. Where are you aging? Kentucky rickhouses behave differently from a warehouse in a drier or cooler climate. Traditional rickhouses, palletized storage, or metal warehouses all change airflow, temperature swings, and flavor extraction. Shorter aging programs may benefit from lighter chars for faster extraction. Longer aging might lean on heavier chars to preserve balance.”

Choosing Your Char

So, what’s the perfect barrel profile for your whiskeys? How do you go about figuring that out?

Understandably, everything we’ve discussed up to this point could over-burden even an experienced distiller or warehouse manager with paralyzing confusion. But it needn’t be that bad. Here are the steps I would take when trying to answer such a vexing question:

Understand the end profile you’re after.

Are you shooting for something with a bit of smoke, or do you want a bit of sweetness and more vanilla-caramel notes? Smokiness would necessitate a bit of char No. 4 (or higher) in the mix, while sweet notes often come more from lower chars, such as 2s and 1s.

Understand your new-make profile.

Is it sweet and clean or a little funky and feinty? A cleaner new-make can pick up a lot of complexity from lower char levels. However, a new-make that is a bit feinty can often use a higher char level to clean up the distillate a bit.

Consider your entry proof.

A lower fill strength favors a faster extraction of barrel compounds. That can be a boon for users of low-char casks, allowing more color, sugars, and sweet notes to enter the whiskey more quickly. (That’s not to say that barrel entry proof means a faster maturation—it’s much more complicated than that.)

Understand your warehouse and how long you think maturation will take.

Lower chars don’t always present their best selves for several years, but eventually they blossom into really aromatic whiskeys. If you’re shooting for a faster maturation period, then a heavier char often gives the impression of a more mature spirit at a younger age.

For example: In our own warehouse at Iron City Distilling, we find that our char No. 4s show really well starting at about two years. (Our warehouse is steam-heated year-round to keep the temperature no cooler than 80°F/27°C. This hastens the extraction of various wood compounds and the interaction with the heavier char layers.) Meanwhile, our char 1s and 2s are proving to be some of the most exciting whiskeys in our inventory, but the lower level of char interaction means their new-make character takes longer to soften.

And here’s the thing: There is no rule anywhere that says you have to settle on just one char in your warehouse. Personally, I often advocate for a multi-char approach, especially in my own warehouses. Currently, ICD uses mostly char No. 4s with a smaller percentage of 3s, 2s, and 1s. (We also have a few experiments going with 5s, 6s, 7s, 8s, and 9s, but these are really small lots of casks.)

Now that ICD is nearing its third year of production, I’ve tried to think forward a few years about how I want to manage the inventory. The char No. 3s and 4s will allow us to have some of our whiskey hit shelves sooner, at a younger age. But I also know that as time moves on, I’ll want to generally bump up our overall age statement on most products. So, I’m going to allow for more of our whiskey to sit in lower-char casks for increasingly longer periods of time. I’ve already started the discussion with our cooperage partners to begin that transition, as I think about what and where I want our whiskeys to be in six to 10 years.

But there’s an even better reason to have multiple chars in your arsenal: You’ll have a greater number of flavors and profiles with which to blend. There’s nothing that says a char No. 4 is the perfect profile for every bottle on the shelf. In fact, with the overabundance of so much interchangeable liquid hitting retail stores these days, tweaking your flavor profile through judicious blending from different cask chars is a way to help your liquid stand apart from the pack.

Maturation is a magical thing for whiskey. Because of its often-glacial pace, however, it can be a really scary process to futz with in the distillery; a lot of distillers understandably err on the side of caution and opt for whatever works for everyone else.

However, there’s nothing much to fear. Playing with different char levels could open up new horizons of flavor and product development for your distillery. Besides, in my opinion, anything that helps make your whiskey more exciting is always a good thing.