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The Ancient Craft of Barrel Building

by David on June 20, 2009

The art of barrel building is an ancient craft that goes back to Roman times, and it hasn’t changed very much over all those centuries. If you visit a modern-day cooperage, or barrel-building company, with its blazing fires and deafening pounding, you might think you’ve entered a time machine and gone back a few hundred years. They have some power tools, now, that that didn’t exist then, but otherwise the barrels are still very much hand-crafted. And, to this day, they make these water-tight vessels without using any glue or nails. This is why the title “Master Cooper” is a highly respected one. For a brief video on barrel building, click here.

In Europe there are formal training programs, much like trade-schools, for aspiring coopers. So far, we have no such training programs in the U.S. and so it’s on-the-job training. Consequently, most American cooperages are managed by European-trained Master Coopers.

White oak is far and away the most commonly used wood for wine barrels. There are two species in France, Quercus robur and Quercus sessilus, that are different from those found in the US, which is dominated by Quercus Alba. Eastern European oak, which is the same species as the French, is being used more frequently now too.

In addition to the species, the cooper needs to consider the location of the forest, often in concert with the Winemaker. In France they have a very active reforestation program and to protect the forests, trees are auctioned only once a year in the fall. At that time, an expert from the cooperage goes to the forest, after the trees are felled, to select the best oak for his barrels.

Of course, the wood needs to be free of knots and other major flaws, but beyond that an important consideration is the wood grain. We know from experience that the width of the grain has a significant influence on the rate at which the oak flavor is extracted into the wine, and also tannin, which is important to the wine’s texture and structure. Does the winemaker want big oak aromatics or does he want more structure? The cooper needs to know what kinds of attributes the winemaker is looking for in order to make a good selection.

Back at the cooperage the logs are either split along the grain for French oak or quarter sawn for American oak to begin to form the staves that make the barrel. The difference in splitting vs. sawing means a difference of only 20% of the French wood being usable for barrels, while as much as 50% of the American oak can be used, reducing the cost considerably. It’s not that they wouldn’t like to saw the French oak, it’s just that the physical properties of the wood won’t permit it. For French species, sawn barrels mean leaky barrels.

Most winemakers will decide whether they want to use French or American oak, based upon the stylistic impact they’re trying to achieve and perhaps their budget. Many use both and blend, as we sometimes do here at Goosecross. 60-gallon French oak barrels cost around $1,000.00 these days (2009), where an American barrel goes for less than half of that. In general, sensorily, American oak is usually stronger in aroma and flavor than French oak, which for one winemaker is perfect, and for another is too much. They can think of the barrel choices as kind of a spice rack.

In either case, the forest of origin is important, and the winemaker may request that the oak come from the well-known Vosges or Allier forests in France, or Missouri, Minnesota or Virginia oak among other choices here in the US. About 90% of our barrel inventory at Goosecross is French. Geoff Gorsuch, our Winemaker, prefers a subtle influence and introduces in just a little American oak for extra spice for certain varieties. He has also purchased a small number of Hungarian oak barrels for research purposes.

The newly formed staves are stacked outside to age and dry in the sun, rain and wind for a few years. The rain is crucial for depleting tannins in the wood and mellowing it over time. After they’ve reached about 16% moisture, they’re cut to the proper length, tapered at each end and beveled.

With a practiced eye and years of experience the Master Cooper carefully selects the 25 to 30 staves it takes to put a barrel together. Because he can’t use any glue or nails, he needs to choose a combination of staves that will form a water-tight vessel perfectly. He makes his selection and raises the barrel with dazzling speed, holding the selected staves together with temporary metal hoops. At this stage, they call it a rose.

Now, to the fire! The cooper takes the rose over to a small fire pot, fueled by oak scraps, and sets the wide end down around it. He swabs it with water, which works with the heat to make the wood flexible so he can bend it into shape. He pulls on a cable to slowly arch and tighten the staves into the shape we all recognize. A minority of coopers offer the option of “water bending,” which employs steam to bend the staves into shape. This is done to further reduce tannin in the wood, most often for aging white wine or very soft reds.

After shaping the barrel the true toasting begins. The terminology is confusing because barrels may be charred or toasted. Charring is literally lighting the barrel on fire to blacken and blister it, as is done for whiskey barrels. Charred barrels are not suitable for wine for a variety of reasons. Toasting is indirect heat from the fire and in addition to helping to bend the wood into shape, it works much like a bread toaster, darkening the wood more and more by either prolonging the process or increasing the temperature. The winemaker can request a light, medium or heavy toast and his choice will produce noticeably different flavor contributions to the wine, from slightly toasty, to caramelized, to dark characteristics like chocolate or coffee bean and smoke. There are many other aromatics affected by the toasting method, which is individual to the cooper, that affect the level of spice, nutty or vanilla-like aromas you may notice in the wine later. Some would say that the toasting method and the grain width are the most important choices made by the cooper or the winemaker.

Once the barrel is bent into shape and has attained the right level of toasting a machine cuts a little groove in either end of the barrel, called the croze, to hold the heads, or the ends of the barrel, in place. To make the heads, different lengths of oak planks are cut to fit, and held together with dowels. The cooper places river reeds in between the planks to assure that the head is water tight. The heads may be toasted at the winemaker’s request.

With the heads inserted the barrel is ready for its permanent hoops. This is an extremely noisy affair as the cooper walks round and round the barrel, pounding the metal hoops into place with a block with a very heavy mallet. This method, to the observer, appears to be a sure-fire way to end up on the emergency room, yet these strong, hard-working men manage to do this over and over on a daily basis without incident (for the most part!).

The finished barrel needs to be tested to make sure it’s leak proof, another very loud process which is accomplished by pouring a little hot water into the barrel under pressure to identify any areas of weakness. Then it’s ready for its beauty treatment-it’s planed and sanded to make it look and feel smooth and pretty.

Some coopers sign their barrels! Each one is a work of art and worthy of that signature at the end of the arduous process it takes to bring the barrel together.

A little barrel trivia

  • A French barrel is 60 gallons, which is the equivalent of about 25 cases of wine or 300 bottles.
  • We estimate losing about 5% of our wine annually to evaporation from barrels. It’s called the “angels share.” With about 220 barrels in our inventory at Goosecross, we’re blessed to be host to lots of very happy angels.
  • An empty barrel weighs about 100 pounds and full, about 600! Best to avoid barrel cellars during earthquakes!

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