The classic champagne technique of France. The methode requires that the secondary fermentation which transforms still to sparkling wine occur in a bottle, most often the one in which the wine is ultimately sold (exceptions being very large or small sizes). Secondary fermentation takes place when a carefully measured amount of yeast and sugar is added to still wine and the bottle securely capped. The carbon dioxide released as a by-product of fermentation cannot escape the stoppered bottle and dissolves into the wine, to be released as bubbles when the bottle is opened. Once the secondary fermentation is complete, the wine rests with the spent yeast for at least a year or perhaps several – longer yeast contact generally produces more complex wines. See Champagne.