Editor’s note: This is the second of a two-part series by columnist Doug Skinner about the process of making bourbon barrels and bourbon.

The crafting of bourbon, for indeed it is a craft, creates more pseudo-experts, opinions and arguments than how the world was formed. Certainly many of you have studied bourbon over the years and probably have a preference for one particular brand or distilling technique over others. However, several things are set in stone by law.

First, to be Kentucky bourbon, it must be made in Kentucky. Second, it must contain at least 51 percent corn. And third, it must be aged in a new barrel.

Traditionally, bourbon always has been made in Kentucky, but occasionally other states have distilleries that make, not craft, bourbon. I am concerned only with traditional Kentucky bourbon, a product of years of crafting, of spring water percolated over vast stretches of limestone unique to the region. A product of oak charred barrels stored in stone warehouses until a master distiller deems them ready for consumption.

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Proud Kentuckians claim their bourbon is a product of “water, fire and time,” claiming the three elements are essential for the manufacture of bourbon. They claim the most important of these is the water, and it’s quite true that the nature of the water does have a direct influence on the quality of the bourbon produced. Part of the reason why Kentucky was chosen more than two centuries ago as bourbon-making country was the purity of its water. Most of this traditional bourbon is distilled within a 100-mile radius of north-central Kentucky, drawing water from one of the underground aquifers on the distillery’s property. Twelve distilleries in the area produce 95 percent of the world’s bourbon.

Experts debate on what makes good bourbon, but all agree that the barrels account for 50 percent of the flavor present in bourbon. Sweetness and the flavors of nutmeg, cinnamon, malt, vanilla, caramel and over 40 other spices are released by fire through toasting followed by a 20-second charring of the inside of a white oak barrel. Imagine, when you sip, not drink, bourbon, you are consuming the entire history of that tree. Its 100 years of snow-covered limbs, droughts and squirrels scurrying through its branches.

But limestone water and oak charred by fire don’t alone make bourbon. The Kentuckians boasting about “water, fire and time” may have been a bit simplistic because they forgot to add the fourth ingredient: grains. Before time becomes a factor, distillers must add grains, at least 51 percent by law must be corn (less than 51 percent, and it is considered a whiskey). Corn and other such grains as barley and rye make each brand or style of bourbon unique.

At Woodford Reserve in Versailles, Kentucky, their basic grain recipe is 72 percent corn for sweetness, 18 percent rye for spice to appeal to Scotch and whiskey drinkers and 10 percent malted barley. The latter gives a creamy malt flavor and helps break down sugars in the corn and rye.

This grain recipe, along with the aquifer water and yeast, is then added to a 7,500-gallon mash cooker for several hours. From there it is piped to large cypress wood vats, where it will bubble as it ferments. After three to six days, the fermentation has peaked the flavors.

From the fermentation vats it goes to the first of three copper spirit stills, getting distilled three times, a process unique to Woodford Reserve. Each time the alcohol content increases until it has risen from 40-proof to 160-proof (80 percent alcohol). The leftover solid portion is called sour mash, an alcohol-free, nutrient rich by-product sold to area farmers for feeding their livestock. The distillate, the clear portion, is called White Dog, New Spirit, or as we better know it, White Lightning.

From here nothing can be added to bourbon except demineralized water, which is used to now reduce it from 160-proof to 110-proof. It is as clear as water when added to the 53-gallon barrels but picks up its characteristic amber color from the charred barrels as it ages.

Now comes our final ingredient, time. Typically these barrels are stored in either 150-year-old-plus stone warehouses or more recent wood or steel structures that can mimic the environment of the stone warehouses. After six to nine years, a master distiller tastes several barrels representing a particular batch. That distiller then deems the bourbon mature and ready for bottling or may reseal it for further aging.

Through the above process, Woodford Reserve has now made a batch of single barrel bourbon. They also make a more expensive “double barrel” bourbon by putting mature, aged single barrel bourbon into a new charred oak barrel. It then ages for a year or more, creating a bourbon with even more spices and flavors that can be recognized by a more sophisticated palate. There are single vat and blended bourbons, even chocolate bourbons.

It must be mentioned that as the 53 gallons of bourbon in the barrels are “sleeping,” it loses some to evaporation every year, and that’s called the “angel’s share.” A sign at one distillery explains it this way: “Because we like to think it is the bit of bourbon we are sharing with the angels.”