If champagne sits around long enough for most of its dissolved carbon dioxide gas to form bubbles and escape into the air, we say that the champagne has gone flat.
When we drink flat champagne we don't feel the pleasant fizz of new bubbles forming. To keep champagne tasting good, we want to keep the formation of bubbles to a minimum until we drink it.
Does A Good, Clean Glass Matter?
There's a scientific basis for the idea that champagne retains its dissolved carbon dioxide longer and therefore tastes better if it is poured into a good, clean glass.
It is practically impossible for dissolved carbon dioxide to come out of solution and form a bubble spontaneously in the middle of a liquidso it doesn't happen. Instead, new bubbles tend to form where tiny pockets of air already exist.
Glass Pits And Dirt Deposits
Places that might harbor such tiny pockets of air include microscopic scratches and pits in the surface of a glass, and crevices along the edges of dirt deposits.
Pour champagne or beer into a glass and you'll see that bubbles don't appear just anywhere; instead, they rise in steady streams from a few definite places on the bottom and sides of the glass.
Those are places where tiny air bubbles were trapped when the liquid was poured. Presumably a perfectly made, immaculate glass will have fewer such places and will trigger the formation of fewer bubbles.
Steer Clear Of The Plastic Cup
This same reasoning suggests why plastic cups are bad for champagne drinking. Wateror champagne, which is mostly water doesn't spread out and cover plastic surfaces well.
When champagne is poured into a plastic cup, many air pockets form, each of which is the seed for a column of bubbles carrying the champagne's dissolved gases into the air. Champagne goes flat fast in plastic.