It's an expensive experiment. Boston Beer Co., owner of Sam Adams, spent $1 million and two years perfecting its Sam can; Grand Rapids-based Founders Brewing Co. spent millions refining its canning line.

Of the 2,400 U.S. brewing companies, 97% are small independents. It was inevitable that these hometown brewers would experiment beyond the large-brewery approach, said Julia Herz, craft-beer program director at the Boulder, Colo.-based Brewers Association. In 2012, 3% of craft brewers' beer was canned, according to the Brewers Association, which expects that figure to increase exponentially this year.

Beer's natural enemies are oxygen and light, which degrade freshness and shelf life of the brew; glass bottles automatically trap oxygen and allow light to penetrate. Cans, on the other hand, seal air out and block light.

"You can really do a disservice to beer, quickly, at the packaging [stage]," said Mike Stevens, CEO of Founders, which will launch its All Day IPA in cans later this year. He forecasts a 25% increase in overall volume of All Day IPA after the national can launch. Sierra Nevada's Pale Ale and Torpedo brews were huge hits last year, so it introduced Summerfest cans in late May. Other brewers in cans this summer include Shipyard, Two Brothers and Ska.

"Craft brewers are grassroots, and their sense of storytelling is: one can, one bottle, one keg at a time," Herz said. "There's more room on the actual can to put their story. ... The more they can talk about their personality, the better."

The can needs to do the talking for craft brewers because they often don't have the budget for TV and radio ads. Big brewers, however, are spending to promote their cans. Miller Lite ran a TV campaign from Commonground that asked, "How do you punch it?" and investigated how household items can puncture its Punch Top can. Coors Light's "most refreshing can" TV campaign featured celebrity Ice Cube. And Bud Light has a local campaign with digital, radio and print media in Louisville, Ky., where it's testing its vented can.

Advertising Age is a sister publication of Crain's Detroit Business.