THE BARREL SOURCE EDUCATION CENT
THE BARREL SOURCE
The art of
barrel making, known as cooperage, is an ancient skill. Despite
improvement from modern research, analysis, machinery and wood
selection techniques, the actual barrel making process has changed
very little over the years and is extremely time intensive. To
achieve the highest standards of quality, most of the work must
still be done by hand by a highly skilled cooper. The following
information is adapted from the famous French cooperage Seguin
Moreau, where many premium California wineries … including Clos du
Bois … source French oak barrels.
Every season, when
trees are felled, experts from the cooperage are on hand to select
the best oak wood for use in the manufacture of barrels and vats.
This selection is the initial phase that essentially determines the
quality of the finished product.
The oak is
examined both before and after being cut, and wood is selected based
on many criteria, including tree shape and growing conditions. These
factors determine the textural variety of wood fibers, the fineness
of its grain and its tannin content. Tight grain and fine tannin
content are found in the best wood.
The logs must be hand
split to preserve wood grain without breaking wood veins, which is
essential for creating impermeable barrels. The oak log is first
split in two, then into quarters to obtain wood for the oak staves
(called merrain). After splitting and planing, the stave wood is
stored outside in tiers. Exposed to air and water, the wood is
naturally aged by the weather for several years. During the aging
process, the development of sugars and acids are
|After aging, the staves are formed by machines into
the proper shape and form for barrel assembly. After they are
cut to the proper length, they are tapered at each end and
beveled. Then they are planed on the outside, slightly
hollowed on the inside and jointed by high precision
After being inspected and selected, the
staves are given to a cooper for assembly. At this essential
stage of the manufacturing process, man steps in. The
craftsman with irreplaceable experience and, above all,
appreciation for work well done now adds his personal touch.
The sharp-eyed cooper selects his staves, setting aside those
that do not suit him. Then he assembles the staves inside a
metal hoop that serves as the assembly jig. This operation,
so spectacular in its speed and precision, is what the
cooper calls the "mise en rose" or "raising the barrel."
in place by three metal hoops that have been forced into place, the
"rose" is then subjected to a trial by water and fire in the
workshop, where it takes its final shape. Repeating movements that
are part of the most ancient tradition of his art, the cooper seals
joints by passing a wet cloth inside and outside the staves, then
heating the barrel over a wood fire for approximately 30 minutes.
Rendered flexible by heat and humidity, the
wood fiber can now
be bent by the cooper, who uses a winch to gradually arch the staves
and tighten them to obtain the shape of the barrel body. The body is
held trussed in place like this until the metal hoops are definitely
The length of heating results in a "toast level" on
which the flavors of the wine aged in the barrel will partially
depend. During the heating of the staves, some substances of the
wood are caramelized and develop a multitude of aromas, such as
vanilla, fresh bread, buttered bread, or a touch of nut, that will
be found in the final taste of the wine. Toast level will be
adjusted according to the customers' requests: light, medium or
After the bending and heating of the staves, a
very precise machining step is necessary to trim the ends of the
staves and to cut the "croze," the groove in the staves that
receives the barrel heads. Custom cut to fit the croze, the heads
are produced with every respect of the most traditional rules for
barrel making. Parts are assembled exclusively with dowels and
natural, soft, flexible and rot-proof river reed to provide a
|The cooper then finishes the assembly of his
barrel. The body is set up and the heads fitted into the crozes that
have been coated with a paste of wheat flour. Then comes the final
hooping, put in place with a large mallet. |
Once the barrel
is finished, a rigorous test of impermeability is made, by pouring a
small amount of hot water under pressure into the barrel. This
procedure makes it possible to immediately detect any leaks, or mere
traces of moisture caused by an unusually porous areas or
After the barrel is inspected and
passed, the cooper does the final finishing work, planing and
sand-papering to enhance the quality of the oak used and the
perfection of the workmanship. His work finished, the master
craftsman signs his name on the barrel, a custom that has existed
throughout the history of French barrel making.
notice that both French and American oak barrels are used to age
many wines. While the barrel making process is similar for each, the
wood imparts different characteristics to the wine being aged.
Winemakers may choose a combination of the two to achieve a
particular effect in the finished wine.
difference between French and American oak? Simply put, French oak
adds more subtle flavor to wine, while American oak is more
aggressively flavored. Once again, the use of French and American
barrels of various ages provides a broad spectrum aromas, flavors,
and textures to the blend, in much the same way as cooking with many
ingredients improves the flavor of food.
In the past,
American barrels were known to be overly aggressive, which was
blamed on the character of the wood itself. It was then learned that
the methods used to make barrels in America, while suitable for
whiskey, were leaving too much flavoring in the wood. When American
coopers began applying French methods to American oak, the resulting
barrels, while still more powerful than the French, were very well
suited for wine.
Kiln Dried Wood
|Old American Wine Barrel:
|Modern American Wine
Air Dried Wood
|Air drying of stave wood outside softens the
barrel tannins. The gentle toasting of the inside of the barrel
changes the physical and chemical properties of the wood. The heat
caramelizes sugars in the wood, giving rise to new compounds which
add complexity. The toasted wood also acts as a buffer between the
wine and the raw wood underneath. Both barrels in this exercise have
"medium" toast. On the inside, they have the color of cocoa.
Although American barrels are now made from air dried wood,
stave wood is sawn from the trunk, rather than split, because
American oak has its internal vessels more thoroughly plugged with
structures called tyloses (tie-lows-es). French oak has far fewer
tyloses and tends to leak if sawn. An advantage of sawing is that
more staves can be made from each trunk.
barrels have made remarkable progress in terms of quality since
1990. The differences between many American barrels and French
barrels is now a matter of style. At many wineries, the character of
each type of barrel is used in the same way as seasonings are used
to enhance the flavor and texture of gourmet
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