“There is no such thing as ‘blackstrap rum,’” says Richard Seale, master distiller of Foursquare Rum in Barbados. 

And yet, bartenders increasingly are turning to it as a way to add robust flavor to cocktails. Cruzan Black Strap Rum, in particular, has been popping up on cocktail menus, in large part gaining awareness after Giuseppe González called it out in his revamp of the Jungle Bird, swapping out Jamaican rum for inky Cruzan Black Strap. In Death & Co.’s book Cocktail Codex, the St. Croix rum even gets a poetic callout on the shortlist of recommended rums for Piña Coladas, among other drinks, describing it as “dark as a moonless night and with distinct flavors of molasses and maple syrup.”

True, there’s no official “blackstrap rum” category listed by the TTB or in rum bibles like Martin Cate’s Smuggler’s Cove. Ask around, and the definitions for “blackstrap rum” are fairly anecdotal: It’s made from blackstrap molasses, bartenders will often say. But its defining characteristics are really in its profile: Most will agree that it’s dark and has a robust, often vegetal flavor. Beyond that, descriptors range from licorice and toffee to fennel, celery or unsweetened chocolate.

Still, Seale maintains that “it’s nonsense to speak of ‘blackstrap rum.’” All across the Caribbean, rums are made with some portion of blackstrap molasses, or what he calls “final molasses”—the last processing of sugar cane before it becomes completely unpalatable. “You might as well say ‘molasses rum.’”

In general, Seale explains, sugar cane is crushed into juice, which is then evaporated into golden cane syrup. That syrup can be heated in a vacuum pan to form a dense mass of sugar crystals, suspended in thick, now very dark, syrup. Passed to a centrifuge, the crystals are removed, resulting in brown sugar; the remaining liquid is molasses, aka “fancy molasses.” It can then be returned to the vacuum pan to form more crystals, which are centrifuged again. This process is performed three times, and the final molasses is referred to as blackstrap molasses.

If you’ve ever tasted regular molasses (what most of us simply call “molasses”) next to blackstrap, you know they’re not the same thing. Molasses—generally sold for use in confectionery rather than rum—is thick, luscious and moderately sweet, with a sugar content of about 70 percent. By comparison, blackstrap molasses, which has a sugar content of about 45 percent, is darker and sludgy, and can be bitter and salty.

So if rums like Cruzan Black Strap, Bacardí Black and Kraken Black aren’t blackstrap, what are they?

Short answer: They’re black rums. In other words, relatively young rums, which may or may not be distilled from blackstrap molasses, made dark (or “black”) via caramel coloring added after distillation, to mimic the look of a long-aged rum. Usually, flavoring or sweetener is added to suggest the flavor of molasses—sometimes even the salty-savory-earthy tones of blackstrap molasses. Black rum is “typically much darker in appearance than even 50 years in a barrel could achieve,” says Cate. He’s also quick to point out that there’s a difference between “dark rums”—usually meaning barrel-aged rums—and black rums darkened by non-barrel means.

Black rum typically has been relegated to the bottom shelf, considered to be of poor quality and challenging to drink. Most often, it’s used as a dramatic dark float atop tiki drinks, or mixed into classics like the Corn ’n’ Oil or the Dark ’n’ Stormy.

“It’s bitter coffee,” sums up Tyson Buhler, beverage director of Gin & Luck, who mixes Cruzan with other rums in his Wipeout cocktail to add subtly dark, complex tones. “It’s like coffee that’s been sitting too long on the burner, like bad bodega coffee.” Yet, it also offers a distinct “pancake syrup” flavor that’s otherwise hard to find and plays well with a wide range of other ingredients.

Myers’s is perhaps the best-known of the black rum category—and it was one of the reasons that Cruzan Black Strap was developed. “From a commercial standpoint, the reason we have it is to compete with a Myers’s,” says Gary Nelthropp, master distiller for Cruzan, who describes the brand’s Black Strap as “a flavored rum.” Introduced into the U.S. in the mid-1990s, the rum was given a substantial signal boost when the producer added it to the “Distiller’s Collection” in 2013—around the same time that rum in general saw a revival of consumer interest.

The base is a relatively light-bodied two-year-old rum, Nelthropp explains—and yes, it’s distilled in part from blackstrap molasses, which “contains nutrients that help with fermentation.” The finished rum is later flavored to evoke the character of molasses, though he sees the overall profile as closer to luscious regular molasses than bitter blackstrap. (No, there’s no blackstrap molasses in the flavoring component.)

So why name it after blackstrap molasses? “Marketing,” Nelthropp says with a laugh. It conjures up images of navy ships and molasses-filled barrels, he adds. (In addition to Cruzan’s label language, Bacardí Black also touts its bottling as “developed to pay homage to blackstrap rum.”)

Somewhat unpredictably, Cruzan’s success may have helped spawn the use of actual blackstrap molasses among U.S. craft distillers. But the resulting rums are white—and with no coloring added, they are definitively outside the black rum category.

For example, Rhode Island’s Thomas Tew Widows Walk, an overproof white rum, and Oregon’s Warship Reserved Black Strap rum are both made from blackstrap molasses. So although Caribbean distillers may be using blackstrap molasses by default, says Brent Ryan, founder of Newport Craft Brewing and Distilling, which makes Thomas Tew, U.S. craft distillers are not. Working on a smaller scale and less bound by long-standing supply chains, those who distill rum from nothing but blackstrap molasses have made a deliberate choice to do so.

“As a distiller, you get a lot more flavor using it,” Ryan says; in particular, he favors the “vegetal” character blackstrap molasses provides. He also opted to use blackstrap to emulate domestic rum-making traditions 250 years ago, “when there were 22 distilleries operating within city limits.”

Bartenders are embracing white blackstrap rum as well. At The Eddy (now closed) in New York, head bartender Robert Rugg-Hinds used Widows Walk for “spicy backbone” in the American Tiki cocktail. “It’s a white rum with a different seasoning background,” he explains.

Even as critics like Seale insist that blackstrap is a misnomer, these deliberately dark, brooding bottles are unlikely to go away anytime soon. But don’t expect this flavored rum to appear as a star player in, say, a Blackstrap Rum Old-Fashioned. In smaller increments, however, bartenders are continuing to reach for it to add depth of flavor to drinks.

“It’s not a rum that I particularly want to enjoy on its own,” sums up Buhler. “But it’s a flavor that we can’t find anywhere else.”