🍷 Demijohn

A demijohn, or carboy, is a large bulbous glass bottle with a narrow neck, traditionally encased in wicker. Historic demijohns held from about 4.5 to 45 litres. The wicker, bamboo, reeds, willow twigs or sometimes leather protected the fragile glass in storage and shipping.

The name appears as dame-jeanne in French, damigiana in Italian and damajuana in Spanish. Demijohns held wine and other liquids: in Italy, large wicker-wrapped bottles held open wine that buyers brought to be filled, and in Portugal and Spain sherry and port matured in demijohns before being decanted into ordinary bottles. They also carried olive oil, brandy and rum.

In home winemaking, a glass or plastic carboy of 1 to 6.5 gallons serves as a secondary fermenter. The wine is moved into it once its specific gravity falls to about 1.020–1.030. An airlock partly filled with water lets carbon dioxide escape and keeps air out. During active fermentation the carboy should not be filled above its shoulders; afterwards it is filled to within a few inches of the airlock to limit oxygen exposure. Everything that touches the juice or wine must be washed, rinsed and sanitised.