It may come as a surprise to learn that you don’t need brute force, or a sharp blade, or quick hands to execute this technique (though it does help to be kind of a badass, like Neal Stephenson, for example). In fact, it's all about finesse.
Here’s why: A bottle of Champagne is under about 90 pounds of pressure per square inch. The diameter of the opening is less than 3/4-of-an-inch wide, so there is a force of roughly 35 pounds pushing on the cork at all times. In the early years of Champagne-making, thinner glass bottles would regularly burst in the cellar, as secondary fermentation released carbon dioxide into the bottle and increased the pressure. Among other mitigating techniques, Champagne houses added wire cages to hold in the corks, and thickened the glass to more effectively contain pressure.
These days, a Champagne bottle usually won’t break for no apparent reason (though they sometimes do), but the key to sabrage lies in one important detail: No matter how thick or strong the bottle is, glass is still a brittle material (meaning it will break instead of bend when pressure is applied). And just one well-placed scratch on the surface will compromise its integrity. In this case, a light score along the 90-degree angle underneath the lip of the bottle creates a microscopic crack where the bottle is weakest. With just one fluid nudge from your saber, the pressure inside the bottle cleaves and opens a crack in the glass, releasing the collar of the bottle and the cork along with it. If done right, the neck won’t shatter or splinter; it will break off with a clean split. That’s because the saber itself doesn’t actually break the bottle, but simply propagates a fracture that allows the pressure inside the bottle to release.
This may take some practice, so chill a few bottles and stand away from others to minimize risk of injuring someone with your sword or flying glass. Once you get it right, it’s a pretty sweet party trick practiced in the tradition of the likes of Napoleon and master sommeliers. Oh, and blade aficionado Neal Stephenson.
Get the full technique at Chefsteps.com