Charmat method

What it is

Federico Martinotti, director of the oenological institute in Asti, patented the technique in 1895. Eugène Charmat refined the equipment in 1907 with an industrially viable autoclave. Hence the double name: in Italy the method officially goes by Metodo Martinotti, while internationally it travels as Charmat or cuve close. The core remains the same: second fermentation happens not in the bottle but in a sealed pressurised stainless steel tank.

How it works

A still base wine enters the autoclave together with liqueur de tirage (sugar plus yeast). The tank is sealed. Yeasts convert sugar into alcohol and CO₂, which dissolves into the wine because the pressure cannot escape. The process runs anywhere from 30 days to six months, depending on the target profile. After that, the wine is filtered isobarically (under pressure, so the CO₂ does not bleed off), dosed and bottled.

Key parameters:

• Pressure: 5 to 6 bar final pressure, comparable to bottle fermentation
• Temperature: 12 to 16 degrees, lower than bottle fermentation for finer aromatics
• Lees contact: a few weeks for standard Charmat, six to nine months for Charmat Lungo

The variants

Charmat Lungo is the lesser-known version where the wine stays for months on dead yeast inside the tank. Producers like Bellussi and Bortolomiol apply this to Prosecco Superiore DOCG. The results edge noticeably closer to bottle fermentation in texture, although the aromatic profile stays distinct: less bread, more matured fruit.

Read critically

The assumption that Charmat is by definition inferior to the méthode champenoise does not survive contact with a well-made tank wine. The difference does not sit in the method itself but in two specific consequences of it. One: short lees contact means little autolysis, so few brioche and hazelnut notes. Two: CO₂ released from a large tank integrates differently than CO₂ formed inside an individual bottle, which makes the mousse less fine-grained.

For grapes where autolysis is not the goal, like Glera, Moscato or the aromatic varieties of Asti, the tank method is the logical choice. Glera held on long autolysis loses the fresh-fruited identity that defines it. The method debate is therefore conditional on what you want from the grape. It is not a quality ladder.

Where you find it

Prosecco DOC and DOCG, Asti DOCG, Moscato d’Asti DOCG, Lambrusco (most versions), entry-level Sekt, and increasingly sparkling wines from Germany, Spain and the New World where producers want an accessible profile without the cost of bottle fermentation.

Cost and scale

An industrial Charmat installation of 50,000 to 100,000 litre capacity costs €1 to €3 million, comparable to a spinning cone but built for very different purposes. The production cycle runs 30-180 days per batch, against 12-36 months for bottle fermentation. One Charmat installation can therefore deliver the output of a traditional-method facility 5 to 10 times larger. For the winemaker that means a fundamentally different capital allocation: less floor space, less bottle storage, less hands-on labour. For Prosecco producers Charmat is therefore commercially the only viable choice given the price segment.

What the glass reveals

A well-executed Charmat wine shows clear primary aromas, a lively mousse (especially in the first 10-15 minutes), and a short to medium finish. It lacks the bread and nut notes that long lees ageing delivers, but that’s exactly what defines the style. An Asti DOCG from Bocchino tastes of fresh white peach, orange blossom and honey, not of autolysis. Anyone wanting Champagne-like depth doesn’t buy Asti. Anyone wanting living fruit aromatics doesn’t buy Champagne. The choice of method follows the choice of what you want in the glass.

For the drinker

Drink Charmat wines young, cool (5-7 °C), and without ceremony. The style suits breakfast aperitif, terrace hour, antipasti platters, fruity desserts. Not for toasts or formal dinner table, that’s Champagne territory. For the value buyer, a €12 Prosecco DOC or an €18 Conegliano Valdobbiadene Superiore delivers more pleasure per euro than an entry-level Champagne at €30. The method isn’t a second choice, it’s a different choice.