Should sparkling wine be stored on its side or its end?
I immediately grabbed my ancient copy of Amy Vanderbilt’s Etiquette: The Guide to Gracious Living to see if she said anything about the correct procedure in her chapter “The Ritual of Drinking.” She does confirm what you say in general: “All table wines should be stored on their sides, to keep their corks moist (and uncrumbling), in a cool cupboard, away from the light and from steam pipes. . . . Wine with plastic corks may be stored upright.” The separate discussion of champagne only speaks to opening it, and she doesn’t exclude it from being served with meals the way she does with port, sherry, and madeira, so I think this instruction may be taken to apply to champagne as well. On the other hand, I would do what the bottle says. (Actually, since I never buy wine except to consume it soon, this isn’t something I’ve ever worried about, and I store everything upright. But that’s in my dorm room, where many rules are suspended indefinitely.
I’m not sure whether this also plays specifically into the label’s recommendation, but I do know that while the champagne is being made, the bottle’s orientation has a lot to do with managing the sediment (mostly yeast) that precipitates or consolidates over time. While the bottles are fermenting, they’re stored at an upside-down angle, with a temporary cork, and turned slightly every few days. (A process called “riddling“, which is apparently part of the widow Clicquot’s claim to fame.) This encourages the sediment to collect in the neck, where it’s later flash-frozen and popped out (“disgorged”) before the traditional mushroom-shaped cork is stamped down. It’s probably moot now, since modern techniques can basically eliminate all sediment from the bottles we buy, but I wouldn’t be surprised if the habit of storing champagne upright initially had to do with getting any residual sediment to collect at the bottom of the bot
