I spent a memorable evening this summer enjoying Kevin Peterson’s strange multi-sensory cocktails at his small space in the basement level of a Victorian mansion in midtown Detroit. By daytime, Peterson’s wife, Jane Larson, makes her own perfumes, which she sells under the Sfumato label. At night, the boutique fragrance store becomes Castalia, where her husband makes cocktails to pair with these scents, which are sprayed onto small sticks that garnish the glasses. It’s an interesting story, but it has been nicely written about before.

For an off-menu selection, dubbed the 30 Year “False-Aged” Old Fashioned, Peterson at first pulled some fairly standard ingredients: Redbreast 15 Year Old, simple syrup, a bottle of bitters. He then plucked a 750-milliliter bottle with only a finger or two of some murky, brown substance at the bottom of it, a quarter-ounce of which he added to the cocktail build. A Sharpied piece of masking tape affixed to the bottle revealed the mystery contents:

More specifically, a full bottle of J.P. Wiser’s 15 Year that had been dehydrated by some 90 percent, down to just those few ounces of muddy liquid.

“I’m always looking for new ways to push flavors in new directions. Flavor impressions people haven’t experienced before,” says Peterson. “And this was something I hadn’t ever seen on a menu anywhere.”

Formerly an engineer for General Motors, Peterson was a regular reader of cult blog Boston Apothecary upon opening his bar in 2018. The blog, written by Stephen Shellenberger, offers case studies on many offbeat distilling-related projects.

“He had cool experiments that could be done fairly cheaply,” says Peterson.

One that Peterson immediately latched onto was the idea of dehydrating whiskey, something that Shellenberger had written about back in 2012. Shellenberger detailed his creation of “bouillon” cubes that he thought could add barrel essence to unaged spirits.

“After dissecting many spirits, I’ve come to realize that the vast majority of sensory attributes that a barrel contributes to a spirit are not volatile at the boiling points of ethanol and water,” wrote Shellenberger, who continues to analyze avant garde distilling practices today. “What this means is that we can remove the volatile constituents and end up with dried barrel essence.”

In Shellenberger’s case he turned a bottle of Old Grand-Dad into a powder that strictly had the flavors of the barrel — vanilla and char for example — but without any of the flavors of grain components. He would initially use a technique called vacuum reduction, which isn’t quite as esoteric, dangerous, or as expensive as one might think. He attached a Comeau vacuum aspirator (which he had acquired used for just $75) to a vacuum flask that he heated by a hot plate on low, so the solids would not scorch.

Peterson would opt for a standard food dehydrator, however, no different than the ones hippies use to make dried fruit for long hikes. He poured the whiskey into little ramekins typically used for bar snacks and placed them on the dehydrator tray, setting the temperature to 150 degrees. He claims Castalia’s small kitchen smelled like a rickhouse as the whiskey began evaporating.

After several tests, Peterson felt like a powder was too hard to reintegrate back into a liquid (quote: “a pain in the ass”). So he started to dehydrate down to the murky state, just before powderization. He was pleased with the flavor of what he had left.

“It had a lot of that ‘Oops, I left some Scotch in my glass before bed,’” he explains. “It still smells like whiskey — caramelly, a little brown sugar — but you take a sip and it’s pretty watery.”

Peterson would try this process on all categories of whiskey: a wheated bourbon like Maker’s Mark, Rittenhouse Rye, even Mellow Corn. Though the science says the unique aroma and flavor attributes of each whiskey’s mash bill should have evaporated into thin air, he swears he can still tell them apart.

“I’m not super sure what chemistry is happening,” he says, “maybe all the [aging] time gives the corn or wheat aromatics time to bond to the barrel and leave those characteristic notes.”

Shellenberger says that’s the concept of “fixation:” theoretically volatile things not actually evaporating fully. Sucrose, for example, can have a fixative effect and hold onto an aroma that you would think would otherwise blow off.

Whatever the case, Peterson now had an interesting ingredient to work with.

Peterson would unveil this “False-Aged” Old Fashioned at a ticketed Valentine’s Day event earlier this year. The concept of the night was “time as an ingredient,” with each guest getting cocktails that played with the theme. For what he called The Fountain of Age, a 15 Year Old Fashioned was served beside the dehydrated whiskey-spiked one.

He settled on using the J.P. Wiser’s 15 Year due to its more economical price (around $45) despite the elevated maturity. Add a quarter-ounce of it to 2 ounces of Redbreast 15 Year Old and…

“‘Oh shit! A 30-year-old Old Fashioned’ is the typical reaction,” says Peterson.

Still, it has never appeared on a standard, day-to-day menu at Castalia due to costs. While the equipment and technique are not exactly pricey, the amount of whiskey needed doubles the standard cost of a cocktail. Two ounces of J.P. Wiser’s are needed to dehydrate down to the quarter-ounce used alongside 2 more ounces of Redbreast.

How often do you see 4 ounces of 15 year whiskey deployed in a single-serving Old Fashioned?

That’s probably why, as far as I can tell, no other bartenders in America have really explored this concept either, even though it hardly takes any laboratory prowess.

“Literally anyone can do this,” says Peterson. “You could even do it super low tech; you would just pour the whiskey on a plate and leave it out overnight.”

Over the past decade, numerous bartenders have toyed with dehydrating liqueurs into sugary powders, dusts, and crystals, namely Campari and Chartreuse, which would then be used as a garnish on the rim, not as a component of the drink. Cocktail writer Camper English, with an assist from bartender Jacob Briars, dates this practice as far back as 2005, when Aussie bartenders Mick Formosa and Ben Walsh engineered Campari “dust” by placing the amaro in a roasting pan inside a lightly heated oven.

“There was the trick of dehydrating Aperol and adding it to Everclear to make higher-proof, more intense Aperol,” recalls English, whose latest book, “Doctors and Distillers: The Remarkable Medicinal History of Beer, Wine, Spirits, and Cocktails” came out earlier this year. “A few bars have put that or a version of it into [a cocktail].”

Shellenberger admits that he is no longer really on the cocktail scene and, indeed, his goal for this process, over a decade ago, wasn’t in the cocktail realm either. He was more interested in using his barrel essence powder to make an unaged spirit taste more mature.

“The ideas were eventually used in a more serious context to create ‘sketching’ techniques for distillers,” explains Shellenberger, who eventually switched to using a dehydrator as well. “If you cannot find a role model spirit on the market, try sketching it out and see what tensions get added to the sensory matrix.”

In other words, quickly testing theories like whether a particular fruit eau-de-vie might be worth putting into a barrel. For instance, with a Kuchan Indian Blood Peach eau-de-vie that he never particularly enjoyed; adding the powder “push(ed) the ordinary into extraordinary” Shellenberger felt. He is also aware of certain home distillers who have explored the technique to get a glimpse of what their distillate might taste like if they could produce enough volume to mature it.

This dehydration technique would lead to further offshoots, like cutting spirits into a volatile top and a nearly non-volatile bottom, then mixing and matching them, sometimes while also removing water.

He would make an overproof Old Overholt — which actually became a bit of a reality when the brand released a Bonded version in 2018 — and a Fernet 151, as well as what he called “sugar-swap” Chartreuses that removed a bottle’s non-aromatic white sugar component and replaced it with a more aromatic sweetener like ​​jaggery. Those experiments were eventually duplicated by followers as far away as Vietnam.

And, a decade later, Peterson was inspired by Shellenberger’s dehydration experiments to make the most interesting cocktail I’ve tried this year.

“You can pull strings to play with the symbols just as easily as the sensory values and that is where storytelling, silliness, and the ability to cement memories comes in,” says Shellenberger. Or, as Peterson more succinctly sums up:

“I thought it would be fun to create a false idea for people.”