Why Do Champagne Corks Expand After the Bottle is Opened? Why do champagne corks expand after opening the bottle? It all depends on how long the cork has been in the bottle. Champagne for at least 15 months (the law in champagne), it then gets disgorged looking like the one below. Since most champagne is consumed relatively If you ever open an older bottle of champagne—I have had some that has As a side note, aging your non-vintage champagne for one year makes a