The magic cognac pot still! How does it work?

Distillation takes place in traditionally shaped copper stills, also known as “Alambic Charentais”. Also known as alembic, it depends on the language.

Process of Distilling Cognac: Bad wine makes great brandy

The design and dimensions of the pot stills are legally controlled. Two distillations must be carried out; the resulting eau-de-vie is a colorless spirit of about 70% alcohol (the aging process afterwards makes the alcohol level drop to around about 40%).

How does Cognac distilling work?

The wine that is supposed to be used for the pot still is called Vin de Chaudière. Basically, it’s not the best wine in the world – it’s actually quite a lousy wine to drink. But there is a reason for this of course: The wine should be low in alcohol, only around 9%.

At the same time the wine should not be too intense in terms of aromas and taste. This is necessary for producing good eau-de-vie.

Is it true that you need bad wines to produce good Cognac?

Also, the wine needs to be acid so the chemical reactions work better. The lower the alcohol degree, the better the concentration of aromas. The wines dedicated to Cognac production are basically quite natural, because the wine makers do not add anything superficial to the process.

Process of Distilling Cognac: Bad wine makes great brandy

Nothing to make them sweeter, more balanced or to protect them from bacteria. This totally restricted in Cognac-making, it’s simply not allowed. The grapes must be totally clean and pure, no additives whatsoever. It would create an aroma one would notice in the eau-de-vie afterwards – as it becomes so concentrated.

Regarding the grapes: There are some varieties one can use for producing wine that is used for distilling. There is only one single variety, which is used by almost everyone in Cognac: Ugni Blanc. Okay, this could seem a bit boring. One single variety only?

Alembic Charentais

The basic procedure of distilling is quite simple: You heat a liquid and it starts evaporating. If the vapors then get in contact with a cold surface, they condensate.

1. Creating the eau-de-vie

Alcohol evaporates quite easily. So if you heat wine, the vapors are quite concentrated with alcohol. The vapors that make their way through the pot still are more concentrated with alcohol than the liquid that remains in the boiler.

The wines are injected to alembics, where the boiling of wine produces vapors. The vapors go into tubes, which pass through cold water – the tubes are cooled and the vapors inside as well. They then condensate into eau-de-vie: Far less in quantity and much more concentrated than the original wine.

Alembics park at Rémy-Martin

So in theory all this seems to be easy. But it isn’t. There are so many different distilling techniques, rum, gin or whisky distillation works very differently. Every brandy from Obstler to Armagnac to Spanish brandies. The Alembic Charentais (the pot still from Charente) is very different to others, such as the Armagnac pot stills. Spirits are all produced in slightly different way.

The Alembic Charentais is not something one can just build like that. Exact rules are set and it is exactly described how the alembic is supposed to look – and how it’s supposed to work. And this has been a tradition since decades.

First, an Alembic Charentais is made of copper, because heat spreads well in the metal. The “chapiteau” and the “chauffe-vin” look like huge balloons. The bricks it is built on guarantee a stable ground for the huge tool and a good isolation.

Pot still and fresh eau-de-vie

2. Cognac gets distilled twice

The wine in the “cucurbite” is heated and the vapors rise, pass through the swan’s neck and then condensate into the serpentine. The liquid, which comes out of the alembic is quite low in alcohol, about 30%. This one is called “Brouillis”.

The distiller will do this procedure twice. The Brouillis is distilled one more time, called “seconde chauffe” or “bonne chauffe”. And during this step, the final eau-de-vie is produced.

The next part is called “coupe” or cutting. The distiller separates the “hearts” from the other parts of the liquid. The “hearts” holds the delicate fragrances of flowers and fruits, it’s quite a complex process: Liquid comes out of a tab, the heart somewhere in the middle of the flow, at the end the “tails”.

The eau-de-vie at this stage is totally transparent, also called “Blanches” -it looks just like water. It only gains its golden color by being stocked in oak barrels for at least two years.

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Process of Distilling Cognac: Bad wine makes great brandy

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Author

Max is a spirits expert and speaker, into marketing, technology, startups, and business development. He’s also a farmer. He likes tools and machines, Game of Thrones, and Better Call Saul. Included in his Top 10 Cognacs are the Audry XO and Bache Gabrielsen 1973.Max founded Cognac Expert in 2010 at his family’s estate in Poullignac, in the Cognac region, France. Started as a blog, today Cognac Expert is the world’s largest website about all things Cognac, a blog, and a specialized online shop featuring 800+ different Cognac bottles.

9 Comments

  1. Avatar

    I think this blog post was actually a sweet start to a potential series of articles about this topic. A lot of users act like they comprehend what they are talking about when it comes to this area and in reality, hardly anyone actually get it. You seem to understand it however, so I think you need to start writing more. Thank you!

  2. Avatar

    I need information on the specifications of the wine pre-heaters on the Alembic charentais cognac stills. is the Wine pre-heater the same size and capacity as the Boiler section “(cucurbite)” or are they different, and what ever the answer, is this always the case?. Also could you provide information on how they are used exactly in the production of Cognac or Calvados?

  3. Avatar

    Very informative article! Great depth and breadth. We make an Eaux-de-vi of grapes, Pisco from Peru using Charentais stills and the 8 grapes we harvest by hand and ferment into wine are very ripe when harvested and inherently flavorful make great tasting eau-de-vi. Eaux-de-vie of grapes is a broader category than brandy/cognac;). You should taste our Piscos…they’re smooth and packed with flavor ranging from dark chocolates and pepper to stone fruit to jasmine and white flowers….all from the grapes. The DOC in Peru dictates no wood aging and our eau-di-vie is better for it.

  4. Avatar
    Jonathan

    Is it the same equipment used to make cahors wines russian style, which is wine must heated to seventy degrees celcius before fermentation? what about grape vodka?

  5. Avatar

    I only plan to make small batches and I don’t have any oak barrels. Can I just add some oak to glass or stainless containers? Any kind of oak better than others?

  6. Avatar

    Just a note; cognac condenses. Condensate is a noun, the product of condensation.

  7. Avatar
    Katja Verkh

    Hey Mike!

    Thanks for the comment 😉

    Wish you a nice day!

  8. Avatar
    David Fryer

    This article is really inaccurate. The cognac region used to use Colombard, not Ugni Blanc, because it was a better wine that produced a more flavorful cognac. They switched to Ugni Blanc after a phylloxera outbreak destroyed the Colombard vines. As Ugni Blanc was phylloxera resistant, that became their new go-to wine. They continued this practice to protect the region name. However, better wine does make better brandy, as is clear from the brandy being made using the Cognac method but with varietals such as Pinot Noir, Semillon, and Colombard by the California producer Germain-Robin. No, bad wine does not make better spirits. Bad wine makes cognac because of a disease and regulations. Better wine makes better spirits.

  9. Avatar
    Katja (Cognac-Expert.com)

    Hello David,

    thanks for your comment! We will re-check our sources and the provided information accurately.
    Thank you for the hint.

    Have a good day!

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