In the back of Schooner Exact brewery in SoDo, behind the towering tanks full of familiar IPA and hefeweizen, brewmaster Matt McClung stands atop a ladder, hovering over a stack of 37 barrels to sample a sour beer he’s aged for over a year—a type of beer that some brewers predict will become the next big thing among Seattle craft brews

Sour beer is a strange creature. The genre dates back hundreds of years to a time when the brewing process wasn’t as sterile and controlled as it is today. Airborne microorganisms occasionally “contaminated” brews, creating tart, funky beer. Over time, brewers—particularly in Belgium—learned to corral the microbes into a sour beverage that can be complex as wine, sharply fruity, or tempered with malty flavors.

McClung, who founded his brewery in 2007, wants to make these heretofore-obscure beers a cornerstone of his program. Working with special yeasts and bacteria cultures, he incorporates fruit like raspberries or apricots and ages these creations in oak barrels for as long as two years to add depth. While the brewer knows exactly how long it takes to produce his Profanity Hill porter, crafting a sour no one else has made before is a matter of tasting, tinkering, and making it up as you go along. The aging, the experimenting with new recipes, and the fact that sours are just now starting to gain traction in the beer community mean that most local sours come in very small batches, surfacing fleetingly on various bar taps.

Brewers at Fremont Brewing, Elliott Bay, Naked City, Epic Ales, and Elysian, to name a few, are running their own experiments with sour beer, in part because it’s popular among beer geeks and, well, because the brewers like to drink it.

Gradually, the general public is catching on. “Someone might start with amber or pale ale and work their way up to more complex beers,” says McClung. He’s noticed sours appearing more frequently in pubs and tasting rooms over the last five years. It seems to be a natural progression; as Seattleites drink more craft beer, they start sampling weirder stuff. “We’re kind of going through a renaissance with beer. Who knows where it’s going.”

Cody Morris at Epic Ales also has an extensive sour program that includes a sour summer ale called Party Time!!!, barrel-aged lambics, and plans for a sour with local apples. Morris thinks the beer is starting to take off as local breweries realize they have a chance to establish sour programs while the beer is still a newcomer. The tendency of Seattleites to embrace the offbeat could help these breweries along in their efforts, and maybe it’ll be enough to push this new frontier in beer to the mainstream, where Morris thinks it belongs. “I see sours as having the same excitement that IPAs had maybe four or five years ago when they first started getting popular.”

Pucker up, Seattle.

Hoist ’em Here:
Fremont Brewing, Naked City, Schooner Exact, Elliott Bay, Epic Ales, and Elysian occasionally offer their sour of the moment at their breweries.

Brouwer’s Cafe in Fremont reliably has a handful of imported and domestic sours on tap and by the bottle.

Urban Family Public House and Stumbling Monk usually carry a sour or two, though the selection changes.