Oak Barrel Making: Technology Assists HandworkTo make oak barrels in the U.S., Demptos Tonnellerie of Bordeaux, France operates the Demptos Napa Cooperage in California. Traditional hand crafting is augmented with specialized equipment, including laser etching from Dadian Systems, Worcester, MA, to brand the barrels for clients and datea stamp them.

Located in Napa Valley, this cooperage makes barrels from American oak as well as from the staves prepared and shipped from Demptos Bordeaux. (The parent company acquired a large European stave maker in 1999.)

The American oak staves (species Quercus alba), used on barrel bodies and barrel heads and joined without glue or nails, are carefully chosen from an exclusive designated forest in Missouri, selected for its high quality timber. A local stavemaker mills the logs for Demptos.

"Highly skilled in the use of Quercus alba for barrel-making, Demptos Napa Cooperage has demonstrated the qualities of its 'new generation' of American oak barrels both in the United States and worldwide," says Demptos.

The process of barrel making is much the same as in ancient Roman times. Staves are hand matched to establish a symetrical barrel shape, then bent slow over a flame with frequent water showers - akin to steam bending wood for other purposes.

Oak Barrel Making: Technology Assists HandworkWorldwide, Demptos acquired SO.GI.BOIS in 1999, a respected stavewood producer; later expanding into Hungary, South Africa, and in 2007, opening Yantai Demptos Co. in China.

Controlling the oxidation process in wines depends on the choice of wood grain for the barrels, notes Demptos, since porosity plays a crucial role in the degree of aeration of wine during aging. Porosity and wood grain are intimately connected: the higher the porosity, the finer the grain. Tight-grained wood is the most porous, promoting exchanges between wine and the cellar atmosphere.

Results of a five-year research project is summarized in a science report:

Clarification of the main conditions for good quality wood: oak selection
Previously, cooperage-grade oak was always selected on the basis of its area of origin. This approach was challenged by Nicolas Vivas, who showed that oak selection should be based on grain tightness.

A video by customer Goosecross Cellars winery in Napa Valley shows barrel making at Demptos in Napa Valley, CA. Goosecross Cellars co-owner Dave Topper has written an very good summary of barrel making craft, and notes that unlike Europe, the U.S. has no cooperage training programs, even though U.S. wines (as well as spirits) and our oak and hickory barrels used to make them are popular around the world.

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