Type and origin of wood
Only oaks exclusively from the Limousin or Troncais region may be used for the production of barrels used for cognac maturation/ageing. The regulation specifies the minimum age of oak intended for the production of a barrel for maturing cognac at 100 years. As with the recommended cognac maturation times, this limit is well exceeded and producers use oaks up to 120 or 140 years old.
Forest selection and its reproduction
The reproduction of the forest is ensured by the regulation, according to which two young ones must be planted instead of one old oak. The choice of forests specified in the regulation was not random. The manufacturers researched the properties of different oaks and eventually opted for the two areas. Oaks grow in the forests of Limousin and Troncais, which have their own specifics that distinguish them from oaks from other parts of France or from other countries of the world. They grow faster and have a softer composition. They are richer in tannins than other species and therefore these trees are mainly used for eau-de-maturation/ageing.
Wood splitting
After the oak has been harvested, its wood is not cutted longitudinally but splits in order to preserve its longitudinal structure, which ensures watertightness. Strict quality control of each piece of wood is a matter of course. Defects in the wood may occur during processing and therefore some pieces are set aside or discarded completely for use in the manufacture of barrels.
Drying
After splitting, it is extremely important to let the splints dry. Oak generally contains about 35 to 40% water, which must be reduced to 14 to 18%. Natural drying takes place in the open air and lasts for three or more years.
Processing of splints
The splint prepared from dried wood is planed in an arc, which later gives the formwork the round shape of a barrel. The edges of the plate are then planted so that they fit together and ensure that the barrel is watertight. Finally, they are shortened to the required length. The smallest splints and those previously discarded due to minor defects at the edges are placed next to each other. Using a large compass, the cooper determines their best configuration for the bottom of the future barrel. The individual splints are fixed with hardwood pegs. The bottom must then be perfectly shaped to fit exactly on the barrel with the required tightness.
Final adjustments before passing the barrel
Oak wood is ideal for the production of barrels, mainly due to its strength and porosity, while its strength must be slightly modified by the barrel manufacturer. First, in order to avoid the risk of breaking the splints and to allow the wood to bend, it is slightly heated in a process called "le cintrage". Metal-hooped splints are placed over a small fire. Due to the effect of heat, the wood becomes more flexible and at the same time it is moistened, which allows it to be joined into the final shape. Gradually, the splints are joined until they close tightly. This is followed by a second, additional heating resp. variable-intensity firing, which is carried out according to the requirements of the cellar master. Already at this stage of barrel production, the final quality of cognac after years of ripening may be affected, depending on the degree of firing inside the barrel.
light
the inside of the barrel is bright
medium
the inside of the barrel is more brown
intensive
the inside of the barrel is almost black
Once the bottom and lid (barrel bases) are in place, a watertightness test follows by blowing water and compressed air through the closing hole. The barrel is sanded at the end with sandpaper and a wooden pin or cork hits the filling hole. A fine fabric is also used to improve the water resistance of the barrel. The barrel is now ready to adopt an eau-de-vie, which will provide the perfect conditions for various length of ageing.