Sales of high-priced whiskeys have been on the rise, nearly doubling in the six years leading up to 2013. The growing affinity for brown spirits has been a boon to distillers like Brown-Forman (BF.B 0.18%), Beam (BEAM.DL), and Diageo (DEO -0.75%), as well as many smaller whiskey makers. But demand has started to outstrip supply, and that could spell trouble. With this trend seemingly in full swing, is it time for whiskey aficionados to start hoarding their favorite hooch?

Source: Wikimedia Commons/Naomi IBUKI

The uptick in interest for whiskey is something distillers could not have planned for. It wasn't long ago that brown spirits were out of favor, and clear spirits like vodka were all the rage.

Today, whiskeys -- including bourbon, scotch, and the Irish variety -- are back in. Sales of American brown whiskeys were up more than 10% in the U.S. last year, and nearly 7% worldwide, according to the Distilled Spirits Council. What's more, there's been a particularly high demand for the better stuff.

Distillers have responded. The problem is that whiskeys are -- more than anything else -- the product of aging. The long rest in wooden barrels is what gives the different spirits their distinctive flavors and characteristics. When beer drinkers gain a taste for India pale ales, brewers can respond quickly, turning out more hoppy batches in a matter of a few months to meet the growing demand. Distilleries don't have that luxury. The whiskeys they're making today won't hit a tumbler full of rocks for several years.

Jim Beam's standard white label is aged four years. Brown-Forman's fast-growing, top-shelf Woodford Reserve is aged an average of more than seven years. The popular Elijah Craig small-batch bourbon: 12 years.

Scotches can be aged even longer. Diageo's Johnnie Walker Black Label is aged a minimum 12 years, and its high-end scotches sit in casks for 18 years or longer.

The top shelf is getting wider
Let's take a step back and see just how big this demand is, and what distillers are doing to try to meet it.

Beam is best known for its namesake bourbon, Jim Beam, the best-selling bourbon on the planet. While Jim Beam sales were up a modest 3% over the first nine months of 2013, the company's high-end bourbons were growing fast. Sales of the much-pricier Maker's Mark were up 17%. Knob Creek sales were up 15%. And sales of Basil Hayden's -- a bourbon that sells for more the double Jim Beam white label -- were up 34%. Brown-Forman's top-shelf Woodford Reserve grew sales by 28% in 2013. At Diageo, sales of its "reserve brands," which include its more expensive Johnnie Walker scotches, were up 26% over the past six months.

The number of small, independent distillers, meanwhile, has grown nearly ninefold over the past decade, according to the American Distilling Institute, numbering more than 623 today.

Keeping up with a growing thirst
Smaller distillers have been innovative in trying to meet increased demand. Some have switched to smaller barrels, increasing the contact between the liquor and the wood for faster aging. Others have experimented with pressure cookers. South Carolina distillery Terressentia may have taken the most radical approach to date, using ultrasonic waves and oxidation to "mimic the effects of long-term aging," the company told The New York Times in 2012.

All are efforts to "cheat time," Whisky Advocate editor John Hansell told the Times.

The larger distillers are trying to meet demand the old-fashioned way: They're expanding their operations for the high-end whiskeys. Brown-Forman has been planning a $35 million expansion of the Woodford distillery, with plans for three new stills "as need dictates." Beam just recently announced plans for a $67 million distillery expansion for Maker's Mark. The project will add a third still to the plant and allow Maker's to bump up production by 50%. This comes on top of $50 million Beam already invested in the Maker's distillery in recent years.

It had little choice, since a plan to stretch supplies by watering down the bourbon to lower the alcohol from 90 proof to 84 drew the ire of drinkers and was promptly scrapped.

The reaction highlighted just how little room the big distillers have to experiment with their top-shelf labels. Unlike the beer industry, where small, nimble craft brewers are often seen as putting out the best products, most of the top-shelf whiskeys you'll find are made by a handful of established companies, including Beam, Brown-Forman, Diageo, Buffalo Trace, and Heaven Hill. There's good reason for this. With a four-year or even 10-year wait on your final product, the barriers to entry are high, and time-honored recipes are a scarce resource.

The Foolish bottom line
With the rise in demand for whiskey, the companies have little choice but to invest in expanding their capacity. Whether those investments will pay off hinges on the fickle, and ever-changing palates of the alcohol-consuming public. Beer was in. Now it's out. Vodka was in. These days, not so much.

In seven years, Maker's Mark and Woodford Reserve will be bottling a lot more bourbon than they are today. Whether there will be a demand for it is anyone's guess. Until then, those who have taken a liking to whiskey should relish the wide selection. And if you find something you really like, it wouldn't hurt to keep an extra bottle or two on hand, just in case.