Wine Barrels: Construction & details 

The average wine barrel has a useful life expectancy of five to seven years. After that time, the oak has little or no beneficial flavor components left to impart to the wine, and the barrel becomes essentially a neutral container.

Barrels can be restored by shaving away several layers from the inside of the staves and re-charring the wood, or by adding inner-stave oak slats. This can extend the life of a barrel up to ten years, however the results are not the same as with new wood. For that reason, after the initial life cycle of the barrel, most wineries purge their old stock. Often these barrels are cut in half and sold as planters — not a very fitting end for a work of craftsmanship.

Construction of a cask

The making of a wine cask or barrel (Wet Cooperage) is a task for only the most discriminating craftsmen. For coopers, quality is intimately connected to the selection and control of raw material. A good barrel can be made from only the best wood, found typically in one-hundred-year-old, or older, trees grown with a trunk diameter usually exceeding five feet. Cooperage oak is of the highest quality, straight, containing no knots or burrs, with little sapwood and regular rings, commonly known as the grain of the wood.

Selection of wood

Logs must be hand split to preserve wood grain without breaking veins, essential to making impermeable barrels. After splitting and planing, the stave wood is stored in tiers, exposed to air and water as the wood is naturally aged by weather. Through exposure to the elements, the wood is purged of impurities, undesirable odors and harsher tannins, which might overpower the flavor of the wine. This aging process takes several years.

After aging, the stave lumber is cut to proper length, tapered at each end, beveled, planed on the outside and slightly hollowed on the inside. After being inspected, the staves are given to the cooper for assembly.

Assembling the cask

The cooper selects the best staves, assembling them inside a metal hoop that acts as a jig. This operation is known as mise en rose or "raising the barrel". Three metal hoops are forced into place, creating a solid hold on the staves, which are then dampened by the cooper. At this point, the "rose" or partially constructed barrel is placed over a small wood fire. During this step, the inside of the barrel is charred or "toasted". The amount of char has an effect on the wine aged in the barrel. Winemakers can select from Light, Medium or Heavy Toast. The Toast decision is made based on the variety of grape and style of wine that will be aged in the barrel.

Wood fibers, rendered flexible by the heat and humidity, can now be bent using a winch to gradually arch the staves and tighten them to obtain the shape of the barrel. The ends of the staves must be trimmed and a croze, or groove, is cut in the staves to receive the barrel-head. Barrel heads are custom cut to fit the croze and assembled using dowels and river reed to make a perfect seal.

To finish assembly, the cooper sets up the barrel, fits the heads into the croze, and completes the final hooping with a large mallet. It takes approximately eight man-hours to produce a single wine barrel.

Next: Woodworking