The cellar master
The aging process follows 3 steps
The newly made eau-de-vie is poured into new casks, where it stays about 1 year. Tannins of the oak barrel will be extracted to be shared with the eau-de-vie.
Then the eau-de-vie is pourred in 'roux' casks, which have contained several years of eaux-de-vie. This is a transition stage where the eau-de-vie starts digesting wood..
Eaux-de-vie, which are allowed to be named Cognacs, start a long micro-oxygenation process full of many exchanges with ambiant air and wood. The alcoholic strength by volume will start decreasing, the 'bouquet' will get more intense and we start identifying the 'rancio'.