Milk Stout Nitro: Left Hand Brewing becomes the first U.S. craft brewer to bottle a nitro beer

Left Hand Brewing will make a big splash tonight by becoming the first craft brewer in the United States to release a nitro beer in a bottle. Milk Stout Nitro pours like a draft beer, complete with a thick, billowy head and bubbles that cascade up from the bottom, similar to the way that bars are able to pour Guinness drafts with special taps.

But instead of using a device known as a "widget" to recreate that effect in the bottle, Left Hand spent two and half years and hundreds of thousands of dollars figuring out another way to gas its beer with a blend of carbon dioxide and nitrogen.

How Left Hand did it is a secret. "We thought about taking out a patent on that process," says Chris Lennert, vice president of operations for the Longmont-based brewery. "But then our process would become public and other people would be able to figure it out."

All he'll say is that the gasses are added throughout the process, "from the filtration to the fermentation to the packaging."

But that's not the only secret Left Hand's been holding. The brewery kept the entire project under wraps until recently, when it took out an expensive ad on the back of Draft Magazine and scheduled a huge party at the Hyatt Grand for tonight. The ad reads: "On September 29th, we declare independence from imported stouts."

"This is a game changer. It's really a game changer," Lennert says.

Guinness was the first brewer to sell nitro beers in a bottle, incorporating a gas-producing widget that would activate when the bottle was opened and create the signature fluffy head on the beer. Since its introduction, the brewery figured out how to inject C02 and nitrogen into the beer itself. Guinness still sells cans with the widgets, however.

The key to making the Milk Stout Nitro work is pouring it hard and not tilting the glass. The point is to release the nitrogen. And in case drinkers have trouble figuring that out, the brewery added a QR code to its striking label that allows people to go straight to a video that shows them how pour.

"Five years ago, we couldn't sell Milk Stout in Colorado," says Lennert. "But it's become really popular, and it has really taken off on draft."

Sixpacks of Milk Stout Nitro will go on sale at liquor stores in Colorado on September 30 for $10 to $11. The silky-textured beer will be for sale in this state only through the rest of year; after that, Left Hand plans to take the beer to all 27 states where it distributes.

Update of last night, with less-than-awesome iPhone photos: