Lincoln County Process: Charcoal Mellowing in Tennessee

by
October 7, 2020

The phrase Lincoln County Process has become closely synonymous with Jack Daniel’s Tennessee Whiskey. But more broadly, it’s associated with the category of Tennessee whiskey itself. At its simplest, it’s the process of filtering new make distillate through sugar maple charcoal prior to maturation. But there’s more to it than that. It’s worth exploring how exactly this process is put into play as well as the resulting impact.

History of Charcoal Mellowing

“The history of charcoal or char/fire for purity and filtration goes back thousands of years,” explains Chris Fletcher, master distiller at Jack Daniel’s.” We don’t know who first applied it to spirits, but we know it was likely done in Kentucky and the northeast prior to ever making its way down to Tennessee. The process of using charcoal to mellow spirits is part of how Nathan ‘Nearest’ Green taught Jack Daniel to make whiskey. It’s how Jack’s family taught my grandfather to make whiskey, and it’s how we will keep making it today.”

Lincoln County Process: Jack Daniel's charcoal filtration vatsJack Daniel’s charcoal filtration vats /Photo Credit: Jack Daniel’s

Therefore, neither Jack Daniel the person nor Jack Daniel’s the distillery invented the Lincoln County Process. In fact, the terminology for this process only arose in the mid-20th century. The common phrase was instead charcoal leaching, which begat today’s charcoal mellowing. “There’ve been many names used to describe it, but mellowing really fits the description because of how the whiskey tastes once it’s allowed to drip through the charcoal,” Fletcher says.

Interestingly enough, a different county even lays claim to the process, according to Charlie Nelson, co-founder of Nelson’s Green Brier Distillery. “Prior to Prohibition, Robertson County was home to the largest producer of Tennessee whiskey in the state—Nelson’s Green Brier Distillery—along with nearly 100 other distilleries,” he says. “Robertson County, pre-Prohibition, was akin to today’s Bardstown in Kentucky.”

Nelson further says the process was sometimes known as the Robertson County Process. According to Chuck Cowdery, a marketing fight on the merits of “Lincoln County whiskey” versus “Robertson County whiskey” stretches as far back as 1866.

The Specifics of the Lincoln County Process

Jack Daniel’s uses 80 individual filtration vats that are 14-feet tall and 70 to 72-inches wide. The vats are filled with 10 feet of charcoal which is burned and created on-site (And what’s better to light the flame than new make Jack Daniel’s itself?). The spirit takes two days to gravity filter through the charcoal. The charcoal in each vat lasts for approximately nine months.

Lincoln County Process: Inside Jack Daniel's charcoal filtration vatsInside Jack Daniel’s charcoal filtration vats /Photo Credit: Jack Daniel’s

“The charcoal could potentially last up to a year, but we’ve found that nine months is a good duration for us based on feedback from our team of tasters,” Fletcher says. “Jack was notorious in his day for insisting on using a large amount of charcoal, closely monitoring the vats and mandating the charcoal be replaced often. And that’s still the way we do it today.”

When whiskey drinkers learn about the Lincoln County Process they’ll hear about things such as sugar maple charcoal. The natural assumption is that the process adds flavor and sweetness to whiskey. But you know what they say about assuming.

“It’s important to note that the charcoal doesn’t impart any flavor,” Fletcher says. “The whiskey goes into the vats drop by drop and works its way through the charcoal and emerges as clear as water. The main flavor impact is the reduction of oily mouthfeel and grainy—mostly corn—flavor.” For the record, a high-corn mash bill of 80% corn, 12% malted barley and 8% rye is used for Jack. Fletcher says that the charcoal filtration allows some of the other flavors imparted by fermentation and barrel maturation to shine. The process doesn’t add flavors or sweetness to the spirit itself.

Process Differs for Each Maker

The other large producer of Tennessee whiskey is George Dickel. Its Lincoln County Process differs in several ways, for instance, the distillery uses 13 feet of charcoal. As opposed to gravity filtration, the spirit is steeped in the charcoal. Also, it is first chilled to a temperature of 40 degrees.

Lincoln County Process: Charcoal at George DickelCharcoal at George Dickel /Photo Credit: George Dickel

At Nelson’s Green Brier, the process is more aligned with what you would expect from a craft distillery. “We’ve built our ‘mellowing tank’ out of a whiskey barrel, so it measures approximately 3-feet tall by 2-feet wide at the belly,” explains Andy Nelson, co-founder and head distiller. “We have removed both heads of the barrel and placed a stainless mesh screen about 8 to 12 inches from the bottom with a piece of wool fabric on top of the screen. We then packed the barrel to just below the brim with fairly large chunks, some as large as the size of a softball, of sugar maple charcoal.”

And that’s where things get fun. “We have fashioned a shower head-like mechanism above the charcoal,” he continues. “After a distillation run, we place the barrel on top of a stainless steel tank and pump the fresh distillate into the shower head, where it rains down evenly through the approximately 2-feet of charcoal and into the collection tank below. One distillation run will take around 20 to 25 minutes to run through our mellowing process. Now the distillate is ready for the barrel!”

Tennessee Whiskey

According to current Tennessee state law, any producer of Tennessee whiskey must use the Lincoln County Process. The exception to this is Prichard’s Distillery, which was grandfathered in as a preexisting dissenter. However, the TTB does not have an official designation recognizing or defining Tennessee whiskey.

The Lincoln County Process is a requirement of Tennessee whiskey according to state law. But beyond the basic definition of the process itself, there’s total leeway for the aforementioned differing approaches. “The beauty of Tennessee whiskey is that while this process is required, each distiller is allowed the latitude to customize the variables to their own liking,” Andy Nelson says. “For example, someone may use much finer charcoal pieces or even much larger chunks than we do. Some may allow the distillate to sit in the vat for much longer, perhaps even soak for a bit as opposed to showering through, and some may utilize a much taller or shorter vat than we do.”

Last but not least is Tennessee whiskey, and therefore Jack Daniel’s … bourbon? We can fight about this all day. But I always go back to the discussion of the square versus the rectangle. A square is a rectangle, though it has extra features which further make it a square. On the flip side, certain, but not all, rectangles are squares. Tennessee whiskey meets all the definitions and requirements of bourbon. But the category prefers its more specific designation tying it to a locale and a process. Tennessee whiskey is bourbon, in the same way that bourbon is whiskey. However, it very much prefers to be called Tennessee whiskey, a classification which not everyone can use.


Now that you know more about the Lincoln County Process, why not try a bottle of Tennessee whiskey?

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