the harvest in juice. A pneumatic press is preferable and only whole, unblemished and undamaged grapes must be pressed to ensure a fine juice having undergone as little oxidation as possible. Having been fermented in the same way as a dry white wine, these juices will give a "sparkling wine base".

Once this has been approved by the INAO (the national institute for labels of origin), a little sugar and leaven are added and the wine is then bottled for a second fermentation in the bottle, known as the "development of the mousse". It takes a further 9 months, and thus approximately 15 months after picking, for this wine to be ready for sale.