From pineapple to cocoa to marshmallow fluff, modern brewers are getting creative with centuries-old vessels called firkins. They use the 11-gallon casks to seal in young beer for a conditioning process where the yeast produces natural carbonation without mechanical pasteurization or additional artificial carbon dioxide.
But what is a firkin? And why are producers embracing this brewing technology?
How Do Firkins Work?
The word firkin refers to a unit of measurement adopted by the British from the Dutch for their small wooden casks of beer delivered to pubs before refrigeration. As early as the 15th century, pub owners and managers would set up firkins in their cellars to stay cool and allow their sediment to settle. Next, they’d tap the firkins with a mallet and then deliver the beer to the waiting patrons via a pump.
Unlike modern brewing styles, when using a firkin, there’s no post-fermentation filtering or pasteurization. So, firkin beers bear little resemblance to the frothy pints familiar to most contemporary drinkers.
“Whatever you’re adding to the firkin has sugar in it, and oftentimes, the beer used as the base still has active yeast,” says Tyler White, head brewer at Grayton Beer Company in Santa Rosa Beach, Florida. “That yeast eats whatever sugar is in the firkin and converts it into carbon dioxide. It self-carbonates rather than mechanically like most beer today. That process always offers a velvety mouthfeel.”
“In the old days, they used a positive displacement pump—instead of just pulling the tap handle and having gas pressure to push the beer out, you’re actually pumping it out with a handle at the tap. There would be a frothing head on the end of the faucet to add head to the beer as it leaves.”
The invention of pasteurization in 1864 made the ales less popular as preservation and storage became more viable.
Vacuum-sealed metal kegs, introduced in the 1950s, replaced wooden casks for brewing because of their efficient tap and delivery systems. “Wooden vessels like firkins, aren’t exactly pressure rated. Stainless steel can handle more pressure while staying true to the style you’re brewing with the right carbonation,” says White.
However, modern firkin proponents note that the flavor of beers made in them is distinct.
“You get really soft aromatics,” says Fraiser Hansen, head brewer at Idyll Hounds Brewing Company in Santa Rosa Beach. “It’s carbonated, but not harshly. It’s warmer and all those ingredients you add like chocolate, different types of hops, capsaicin in peppers all start to open up. The more delicate flavors showcase with this brewing method.”
Jeremy Waters, head brewer at Tin Roof Brewing Company in Baton Rouge, Louisiana, brews in firkins, “to pay homage to the past. The lower carbonation makes them less fizzy than a typical beer. And modern beers sometimes have a harshness whereas cask-conditioning produces a gentler, smoother brew.”
White believes firkins connect brewers and drinkers to the process, too.
“There’s always a little bit of magic in a small format designed to be a one-off tap, using interesting ingredients, presented in a way the general public probably hasn’t seen before. For me, it’s the quickest way from concept to finished product to be creative. It’s also a more hands-on drinking experience watching the brewer tap it, the scent opening up, having the top of it vented with an ice blanket—you’re immersed in a visual display and tasting something fresh and exciting you’ll never experience again,” says White.
Hansen traveled to Sunderland, England to learn how to brew beer in a cask, sparking his love for experimentation.
“I’m kind of a hophead. It’s amazing how a handful of hops produces really cool, fun flavors. We’ve also done stouts with different chocolates, cocoa powder [and] even marshmallow fluff. That’s the fun part of the firkins. You put everything in there, seal it and then it carbonates on its own. The first time you tap it, the surprise is unveiled for everyone, including yourself.”
As fun as firkins are, the one-off nature of the brew and tapping makes their availability limited. But events celebrating cask-conditioned beers are becoming more prevalent.
“The tapping process is so much fun. Everybody gets all riled up and one person slams it in with a mallet and pours the first taste. There’s ceremony to it,” says Hansen. And then there’s avoiding getting wet when the tapping commences. Once hammered in, the pressurized liquid needs a place to go, adding to the visual spectacle.
“The visual presentation of the old-style vessel sitting on a table, being poured by gravity is a trip back in time,” says White.
Firkins also offer an old-fashioned antidote to endlessly market-tested craft brews.
“Most beers go through a brewing process and then a permitting process and along the whole way you taste it,” says Alexis Miller, director of Alys Beach’s Firkin Fête in Florida. “With a firkin, you can’t do that. Once it’s tapped, it’s tapped. You have to drink it. It’s always a surprise. There are a lot of wine festivals. There are a lot of beer festivals. This is something unique for a craft enthusiast.”