It’s Not a Bad Pour. It’s a Mlíko.

At a small but growing subset of American breweries, a wave of obscure, foam-heavy Czech beers is swelling.

The first time you order a “milk pour” from Niteglow Beer Company in Bushwick, Brooklyn, you might think something has gone terribly wrong. The beer itself, a dark lager made with local grains, is fine. The problem, first-timers say, is its appearance: The glass is full of foam.

This is not a mistake. It’s a mlíko, one of several styles of beer pours originating in the Czech Republic, where lagers are intentionally dispensed with several inches of foam — and occasionally, an entire cupful.

“It adds a different layer of texture that most Americans aren’t used to in beer,” said Jonathan Ifergan, 39, an owner at Niteglow.

Generally speaking, beer foam is frowned upon in the United States, associated with the television show “Bar Rescue” and Saturday nights at Sigma Chi. But more American brewers have started to reconsider it. There’s a growing appreciation for centuries-old brewing techniques from the Czech Republic and the specialty taps that make these foam-forward beers possible. You can find a mlíko at Novare Res Bier Cafe in Portland, Maine; Little Lager in St. Louis; and Notch Brewing in Salem and Brighton, Mass., an early adopter.

“A lot of people are looking for ways to differentiate,” said Eric Larkin, 36, an owner of Cohesion Brewing Company in Denver, who was won over by creamy, low-alcohol-by-volume Czech lagers during his honeymoon in Prague. “Czech lagers aren’t all over the place. There’s still room to grow.”