Us Against Stem: Bourbon fights the sloppy pour. Credit: Photograph by Darrow Montgomery

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If you order a glass of wine at Bourbon, you get more than just a glass of wine. Your selection is served in a customized piece of stemware, emblazoned with the restaurant’s logo and a not-so-subtle element of quality-control: The Bourbon wine glasses have lines that indicate the level of a proper pour.

Whether that glass of pinot noir is half-full or half-empty is, as always, a matter of perspective. “They always fill it a little above the line, and it makes me feel like I’m getting something extra,” says Angela Zimmerman, a customer at the Glover Park Bourbon (there is another location in Adams Morgan).

Who knows why Zimmerman gets a heavy pour. Perhaps it’s because she’s a repeat customer. Or perhaps the bartender is being careless.

Whatever the reason, this very act of bartender discretion may be under siege. Thanks to advances in wine-­pouring gizmos, restaurants are increasingly clamping down on servers’ ability to pour as they please.

At Proof, a restaurant slated to open this month in Chinatown, there will be no such thing as a generous or stingy serving. The restaurant will use an Enomatic, a wine-serving system with an automated pour. The bartender will merely push a button, and the machine will dispense a predetermined amount of wine. “It’s exact,” says sommelier Sebastian Zutant, who has chosen to use the average of the industry standard pour, which he says is between 5 and 6 ounces. “It’s a 5½-ounce pour every single time.”

Wine-serving systems like Enomatic and Winekeeper, another option for restaurants, consist of a refrigerated case that keeps red and white wines at their ideal temperatures. When a bottle of wine is opened, it’s hooked up to tubes that not only pull the wine out but also pump nitrogen back into the bottle.

“It’s kind of a preservation system as well as a dispensing system,” says Troy Bock, general manager and wine director of Mendocino Grille and Wine Bar in Georgetown and Sonoma Restaurant and Wine Bar on Capitol Hill, both of which use Winekeeper.

“Every time you open a bottle of wine, the oxygen instantaneously starts depleting the characteristics of the wine,” says Zutant. “Oxygen aids in depletion, while the nitrogen is a gas that preserves.”

In addition to guarding against wine waste, the machines can add a bit of elegance to a bar. “Stylistically, it’s gorgeous,” says Zutant, referring to Proof’s Enomatic.

For now, Proof will be the only restaurant in D.C. with an Enomatic, although Bertrand Lapoire, Enomatic’s general manager for the region, says, “I know of a project that could open in the future.” But, Lapoire says, it’s too soon to say for sure.

Whole Foods Fair Lakes in Fairfax has the only other Enomatic in the area. The automated pouring allows the store to have a self-serving system; by inserting a pre-paid card, a customer can select a 1-, 3-, or 5-ounce pour.

Bourbon, which also uses Winekeeper, says the preservation system helps raise the profile of drinks beyond the bar’s signature whiskeys. “I think it’s a great object for bringing attention to your wine list,” says Steve King, Bourbon’s vice president, director of operations.

But King has found one setback: “With the Winekeeper, it’s easy to overpour.”

That’s where the special glasses come in, and they serve dual purposes: “If you fill the glass [to the 5-ounce line],” says King, “it highlights the name ‘Bourbon.’ ”

According to King, customers’ reactions to the glasses have been mostly positive. “They think it’s a nice touch to further the dotting of the i’s, the crossing of the t’s,” he says. But King admits that some are “dismayed” about it and say the exact measuring makes them feel “under the clock.”

In such cases, King explains the reason for the size of the pour to his customers, one of which is that a fuller glass wouldn’t leave enough space to appreciate the nose of the wine. “We’ve always been an educator’s bar,” King says. “With that explanation, they succumb to what we’re trying to do.”