When the barrel has taken its shape and the heads are assembled, our coopers test its watertightness during the proofing step. About 20 liters of water heated to 70 degrees is introduced inside the barrel through the bung hole. The barrel is stirred and rolled so as to distribute the hot water evenly over its entire inner side. Pressure is then injected, simulating the consequences of fermentation in the barrel, which will make it possible to detect and correct the smallest leak if necessary.
Once this step has been validated, the barrel is emptied. We remove the provisional large and thick circles, and we proceed to sanding the hull to give the appearance and the final silky touch.
The barrel is now ready to receive the final galvanized steel circles, 6 or 10 circles depending on the different ranges offered. Depending on demand, the circles can be painted.
In the past, the barrels consisted of only wooden circles (chestnut, hazelnut, etc.), called rolling circles and placed at the heads. These circles were protected the staves to avoid that the bung was removed from the barrel during the rolling and handling of the barrel in the cellars. They were also used to protect the oak barrel from pests such as the cosson, wood-boring insect, which first attacked the soft wood of chestnut and hazelnut. Today these circles have been replaced by galvanized circles. We find wooden circles (chestnut or hazel) on two types of Bernard oak barrels: Bordeaux Château Tradition and Bourgogne Tradition.