A barrique was a French unit of volume measurement. Barrels were made “in an epoch when wine was transported in boats overseas: four barriques corresponded to 900 liters; this measure was equal to one tonneau, and the boats that carried the barriques measured their carrying capacity by tonneaux».
Barrels were first created for transporting wine. Far from modern inventions, their origins reach back into pre-Christianity, and it seems that the habit of conserving wine in wood begins with the Gallics and Celts. In the past, various types of wood were used, such as acacia or chestnut, but these were later abandoned because of the excessive amounts of bitter tannins released into the wines. Today, the most common type of wood used to construct wine barrels is Quercus sessilis or Quercus robor, the sessile oak (very diffuse in France) and pedunculate oak, both highly prized varieties.
Slavonia and America
While France remains an essential point of reference, both Slavonia and America are both important producers of wine barrels. A crucial difference between French and American oak, Quercus alba, is that American oak lends itself to being sawed, which is never done with French oak, and thus made into barrels with much more ease. However, it’s important to note that the most prized wood is obtained exclusively from very old trees (often over one hundred years), whose age allows the tannins in the wood to mature and soften.
The barrels forests
In France, the management of centuries-old forests (often state-owned), where barrel wood comes from, is strictly regulated in order not to cut down trees that are too young, and never in quantities superior to regulated amounts in order not to deplete the forests. French oak is not the only type to possess great qualities: Slavonian oak can also obtain excellent results. However, the norm has been to cut down young trees, compromising the possibility to reach standards equal in quality to the French oak.
The quality of the cut
The fame of French barrels does not only depend on the type of wood used, but also on the quality of its “cut,” called a quarter split, an art that has been traditionally passed down in France for years. The staves are split, never sawed, along the wood’s natural grain. The split is always made tangentially to the medullary rays (which allow for the radial transmission of the trees’ nutritious sap), which run vertically through the trees. This way of “cutting” the tree is without a doubt more highly prized, but quite a bit costlier because of the significant wood waste (see the white part in the top photo), which comes from splitting the wood in quarters.
The staves that are obtained from this (the long planks of wood that form the barrel) will have medullary rays that run parallel to each other, thus reducing the possibility of the eventual loss of wine and excess oxygen. These inconveniences can happen when the rays are perpendicular to the staves, as happens when the natural grain of the wood is not followed, creating flow channels on the inside and outside of the barrel.
A long seasoning
After they are split, the staves are seasoned out in the open, exposed to the rain and sun for a total period that lasts between two to four years. During this time, the wood becomes more compact, while the rains disperse the wood’s green tannins and wash away undesirable components..
Toasting over a natural flame
The flavor of the forest
After the toasting, the heads, or barrel-ends, are added. These are made of lengths of wood assembled in a particular way so as to avoid the use of iron nails. This is where the tonnellerie, or cooperage (the barrel-maker) sears his name and the name of the winery that will use it into the wood. Not only that, but the barrel will also have the name of its forest of origins seared on it, an important indication because—as is also true with wine—the raw material that makes barrels has its own “terroir” and “cru” where the wood grows to acquire unique and recognizable points of quality.
 Maurizio Castelli, 100 domande e 100 risposte sulla Barrique a Emile Peynaud, Compagnie Vinicole Conseil, pag. 15
 Idem, pag. 7