Oak, please

Jean Leon


We're always talking about wine aging in French or American oak barrels. Months of repose in receptacles intentionally crafted to give the wine a different personality. A fuller body, more flavor. A stronger identity. But, what exactly is a barrel and where did it come from?


The origins and history of the barrel

 Thousands of years ago, at the height of the ancient Greek and Roman civilizations, wine was a food of the gods, stored and transported in clay amphorae. It was the most common and frequently used receptacle, but it broke easily. When the Roman Empire conquered Gaul, the Romans discovered that the locals used oak barrels to store their beer. They learned how to make barrels and realized it was the best, fastest and safest way of transporting their wine. In less than 200 years, the famous clay vessel gave way to the oak barrel and in the process brought about an unexpected change in the wine's properties.


A barrel consists of different parts. The image above displays all of the individual elements.


Types of wood and provenance

Keep in mind that oak isn't the only kind of wood used to make barrels. It is undoubtedly the most common type of timber, but cooperages also work with acacia, cherry wood, pinewood and chestnut. Click on the link for more information about each type of wood.

In the past, barrels were made from whatever wood was most abundant locally. However, as it gradually became apparent that different types of wood imparted different properties to the wine, and had different maintenance requirements, winemakers increasingly opted for oak. It is worth noting that oak provides coopers (barrel makers) with the best mechanical properties: wood that is flexible and easy to handle. In addition to these essential characteristics, oak also brings very interesting aromas to the wine.


Alright, now we know why we use oak. Let’s figure out the difference between French and American oak (see image above).

French oak is softer and finer grained with fewer tannins and more vanilla, and it can cost three times as much as its American counterpart. This is due to the fact that French oak, unlike American oak, cannot be sawed, but is split with an ax, with a lot more wood getting lost in the process. French oak barrels allow for prolonged aging, producing elegant, balanced wines with predominant notes of vanilla, dried fruit and nuts, and honey.

As for American oak, it has coarser grain and more tannins. The barrels are more resistant, impermeable, with larger pores than its French counterpart. The notes might not be as elegant, but instead offer a wider range of exotic aromas like coconut, cocoa and smoky or roasted notes of coffee and tobacco.

One of the main differences between French and American oak is the price tag. French oak is more expensive, because it has been sustainably grown for the past 400 or so years. Furthermore, oaks are sold at auctions, and the ONF (the French forestry department) controls the number of trees sold, reserving the right to sell if there is an agreement between buyers.

The trees are grown in a 200-year cycle, which is what gives French oak its weighty reputation.


How does barrel aging affect wine?

The answer is easy. The wood is equally important to the resulting wine as the vineyard, the variety or the blend. There are essentially two reasons. On the one hand, wood allows for controlled oxygenation, which ages the wine and softens its texture. On the other hand—and this is especially true during the early stage of aging—the wood imparts its own tannins and organoleptic qualities to the wine. The wine thus acquires flavors and aromas like vanilla, toast, caramel or coffee, which would be impossible to achieve if the wine didn't enter into contact with the wood. In any case, remember that the length of contact must be adjusted based on the desired wine style. If the wine spends too much time in oak, the wood's rough tannins would end up overpowering the original aromas of the wine.


The making of a barrel

The process is quite complicated, but we'll explain a few of the most important aspects. Below we'll take a step-by-step look at the process of making a barrel:

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  • Splitting vs. Sawing

This is the starting point. These are the two most common methods for cutting logs into staves. When splitting the logs, the ax follows the grain of the wood. The fibers separate, but aren't broken. Sawing implies a pilose exterior surface, well suited to wetness and rather porous (strong saturation and more tannins). American oak is usually sawed, whereas French oak is traditionally split.

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  • Drying and seasoning

The standard empirical rule is one year of seasoning for every centimeter of stave thickness. In other words, two to two-and-a-half years for pieces used in 225-liter barrels and up to three years for 300-liter barrels. “Seasoning” the wood reduces the amount of polyphenols that add to the perception of bitterness and astringency in the wine. At the same time, seasoning increases the level of aromatic compounds in the wood.

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Photo courtesy of Tonnellerie Vinea


  • “Raising the skirt”

This consists in assembling the staves into a shape resembling a skirt. Each stave has a specific name and position in the barrel. Staves are long pieces of wood cut from logs, which are usually 22 to 30 mm thick. They have to be cut to the same length, trimming any excess wood from the ends, which are often split. The staves must also be carefully shaped to ensure they align perfectly flush once the barrel is complete.

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Photo courtesy of Tonnellerie Sylvain


  • Fire bending

The skirt-shaped staves are placed over a fire pot. With the help of a little surface moisture, the effects of the heat and the force of traction, the staves gradually bend to take on the characteristic shape of a barrel. This process is known as “fire bending.”

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Photo courtesy of Tonnellerie Vinea


  • Toast

The barrel is then placed over a flame again, but at a higher temperature to toast the wood's surface. The desired level of toast is achieved by controlling the length of exposure and the heat of the fire: light, medium, medium plus, and heavy. One of our suppliers is a pioneer in ceramic toasting—a revolutionary toasting regimen that makes it possible to toast the barrel very gently and deeply.

The goal of this process is to release substances that impart aromas and flavors to the wine that complement those of the dry wood.


  • The heads

We are nearing the end of the process. The heads are inserted, the wood is planed and sanded, and the barrel is tested for water tightness.

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Photo courtesy of Tonnellerie Sylvain


  • The finish

The final step. The barrel is cleaned and undergoes quality control. In addition, the barrel is branded with the cooperage's logo (either by fire or laser) and other information such as the provenance of the wood, the toast level or the year the barrel was made.

As you can see, the process of making a barrel is long and labor intensive, and barrels play a crucial role in the quality and final bouquet of the wine.

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