Editor’s note: First of a two-part series. “The cooper’s work was not a minor thing in daily life. Wines, liquors, ciders, and beers were all held and aged in casks, and to some extent, they still are.” – William Bryant Logan, Oak: The Frame of Civilization

Not far from Napa Valley, near the shoreline of Suisun Bay facing Mount Diablo, there’s a wine barrel company with a corporate park address and a discreetly marked façade. The location conceals an age-old craft practiced behind its doors. But, according to the master cooper running the show, those doors are always open.

At Tonnellerie Ô in Benicia, Quinn Roberts leads a team of coopers, building oak barrels that rank among the best produced by American cooperages. In some ways, the Napa native and his staff are setting a wine industry standard, not just with their barrels, but through a program to show how coopering and winemaking go hand-in-hand.

Experienced at 48, Roberts is up to the task. He might be America’s only second-generation master cooper. Together with his now-retired father, Keith, the Roberts duo have demonstrated over nearly half a century that their craft is as integral to fine winemaking as almost anything that happens between budbreak and bottling.

“Barrels were made by hand in the old days,” said the younger Roberts at Tonnellerie Ô on a recent morning. “It was the only way it could be done.”

He’d just given a tour of the facility, then sat down in a conference room to talk about silviculture, or the growing and cultivation of trees, and the contemporary craft of cooperage. He also discussed the unique Master Cooper education program Tonnellerie Ô offers to its customers, which incorporates both disciplines.

“In the last 20 or 30 years, with all the advances in technology, barrels have become mass-produced,” Roberts said. “They have to be produced on an assembly line as efficiently as possible. So, being a master cooper has as much to do with understanding those processes and machines as it does with knowing how to use hand tools to build a barrel.”

A dozen craftsmen make up the Tonnellerie Ô assembly line. Under Roberts’ direction they “mass”-produce a little over 40 barrels per day, a fraction of their larger competitors’ output. Still, as a modern cooperage, hydraulics, computers, and even lasers are employed in the manufacture of its wine barrels. So are hammers, drivers, and sandpaper — the hand tools of a cooper’s trade.

Meanwhile, safety glasses and earplugs are just as indispensable. Contrasting its tranquil, glass-walled suites of offices, Tonnellerie Ô’s production floor is a sawdusty, noisy place. And during the chilly morning visit, workers wore thick warehouse gloves: the high-ceilinged space was colder than a wine cave, and oak, like all wood, comes with splinters.

But not all oak is created the same.

Roberts started his tour next to several stacks of French oak staves, the long slats his coopers cut to size to construct the main body of a barrel (shorter staves are used to build the heads, the top and bottom portions). For a current work order, the wood had been milled by the Gauthier family, the cooperage’s go-to French supplier in the Loire Valley village of Méry-ès-Bois. A subsequent order for American oak barrels would, Roberts expected, be made up of wood from Minnesota.

Later, covering the basics of silviculture, he drew cross-sections of American and French oak logs on a whiteboard in the conference room to illustrate differences in the respective trees’ heartwood, the dense material growing a couple of layers under the bark. Such variations are a major factor for millers and coopers alike.

The American species, Quercus alba, or white oak, is harder at its core than French oak. Conversely, the heartwood in Quercus petraea, from which French staves are milled, is slightly porous. This difference in the trees’ anatomies makes for a more laborious, and expensive, milling process in France.

“It’s the main reason why American oak is less expensive than French,” explained the master cooper. “The rule of thumb is that even from a perfect log of French oak, because of its porosity, only about 20 percent of it can be turned into staves. With American oak, it’s double that, at least. So the raw material is much less expensive.”

For wineries that can afford it, the higher price of a French oak barrel is just a cost of doing business. Not all winemakers incorporate oak into their regimen, let alone new barrels or staves from France. But among those that do, a certain style of wine is the desired result: aromas and flavors from French barrel-aging are “sweeter” and often more integrated than they are in American oak-aged wines.

Tonnellerie Ô customers seem to lean French. For 2018, Roberts noted that the sales ratio was about 60/40 French to American stave barrels. Regardless of the origin of the wood, however, his approach is the same.

“I think a lot of times people assume that because you’re a cooper you like a lot of oak in your wine, and of course it’s better for me in the long term if people are using a lot of new oak. But really, in terms of style, I much prefer the restrained, subtle use of oak.”

Unless winery clients request it, Roberts and his coopers avoid making heavily toasted, “high-impact” barrels in favor of products that play a supporting role in the finished wine. “[We] want the wood to complement and respect the fruit in the wine, rather than overwhelm it,” he said. “And, in fact, some of the new barrels that we’ve come up with in the past few years are designed with that in mind.”

During the 45-minute tour, he went from work station to station around the production floor, stopping to explain each part of the process. The “toasting” step—charring the inside of a newly constructed barrel with controlled flames— is of utmost relevance to his winemaker clients, since it will affect the aroma and flavor of the wine to be aged in the finished product.

But before that “most dramatic part of the whole process,” as Roberts described it, a number of things happen, from the initial “planing” of the wood— cutting the broad, top and bottom faces of the staves — to “jointing” or cutting the edges of each piece so they fit together inside the barrel.

Both take place in a sophisticated, two-phase machine called a stave jointer. It’s a room-sized box with a conveyor chain that feeds the staves past different bladed tools, calibrated down to the millimeter for planing and jointing. “In the past, before the invention of this machine, there were separate machines required to do each type of cutting. It’s an amazing piece of equipment!” Roberts exclaimed over the loud, sawing din.

A cooper named Rodney manned the stave jointer, loading the uncut slats of wood onto the chain with practiced rhythm. Another cooper, Sergio, took Rodney’s newly cut pieces and skillfully arranged them inside a pair of thick metal hoops into a “barrel flower.”

The half-constructed oak vessel with outward-splaying staves at one end resembles a bouquet, hence the name. Their boss chuckled that they call it a “rose” in-house. “I mean, ‘barrel flower’ kind of makes sense to me because of the way the staves are arranged. The ‘rose’ part is poetic license, I guess.”

A lead cooper named Alejandro runs the toasting room, where the all-important use of fire occurs. As Tonnellerie Ô’s most experienced craftsman —next to Roberts, himself — he is charged with its most important jobs.

“What Sergio does is he kind of sets the table for tomorrow’s production. He’ll fill this space with about 20 barrels.” Roberts motioned to a set of unfinished vessels resting on the floor. “And then Alejandro and his guys in the toasting room, they come in first every day. They’re here at 5 in the morning, and they start pulling barrels in and begin the bending and the toasting.”

At 8:30 a.m., stepping off of the cold production floor and through the toasting room’s doorway was a bit like walking into a New York bakery on a winter morning. “This is definitely the place to be, you know, until about June or July,” he said. “One reason why the guys start so early is that they want to put all these fires out before the hottest part of the day. So they’re typically finished by around 10 or 10:30.”

Every morning, Alejandro and his colleagues are given work orders for the number and types of barrels they’re going to produce that day. The different types are based on three factors: the wood selection, whether French or American oak; the size of the barrel, which in Tonnellerie Ô’s production can range between 200 and 500 liters; and the toast level the cooperage is trying to create.

“So based on all these factors, Alejandro has a ‘cookbook,’” Roberts added, picking up a three-ring binder filled with pages of written and visual instructions. “For every barrel type and every toast level, he’s given specific instructions about what to do.”

First, to create the familiar, curved shape, the barrel flowers are soaked with water, then heated from within using oak scraps burned in a metal cylinder called a brasero. Afterwards, the bouquet end is slowly bent into place on a floor-mounted device. The alternating water and heat “soften the wood fibers and make them flexible so that we can bend them without breaking them,” Roberts explained, though he confessed that happens most days, anyway.

The barrels are flipped around to receive another pair of sturdy metal hoops, which are carefully hammered around the newly bent staves (these temporary “truss hoops” will be replaced after toasting with the more recognizable, shiny metal hoops that are fitted onto the finished product).

Consulting the cookbook, Alejandro and his team stand the hollow barrels over the braseros, this time burning small, controlled fires with oak pieces specially seasoned for the toasting process. They follow the printed instructions to adjust the size and intensity of the fires, which, after 15 to 20 minutes, toast the insides of the barrels to the intended level.

Roberts flipped to the page in the cookbook that corresponded to the barrel Alejandro was working on, a top-of-the-line French oak model with thin staves and medium-plus toast level. “Given all these specifics, you want him to maintain the fire within this range so he doesn’t let it get smaller than that”— he pointed to pictures of braseros extruding flames of different heights — “and he doesn’t let it get bigger than that.”

He added that Alejandro controls the fire simply by putting in or taking out firewood. As with all of the other steps at the cooperage, however, there was nothing simple about it. “It’s tricky. It’s really tricky, and that’s why he’s an expert. Experience is the key.”

As they went about their tasks, from cutting staves to the final steps of mounting the heads and sanding the finished barrels, the coopers at each station made it look deceptively easy. They all worked with the same focused economy of movement, hardly seeming to notice their boss. Roberts’ own expertise appeared second nature, and his commentary rang with authority. Back In the conference room, it raised the question: how did he acquire this knowledge?

He considered the marked-up whiteboard. “I didn’t go to school for it. I just learned a lot from hanging around cooperages and forests. You know, spending time with our suppliers out in the forests when they’re looking at wood, it’s fascinating.”

This would include regular visits to France’s national forests, or forêts domaniales. As part of Tonnellerie Ô’s popular Master Cooper program, Roberts started taking some of their best winery clients to visit these forests in 2017.

“A lot of the forêts domaniales are concentrated within about an hour to two-hour radius of Paris,” he said. “This is where you find it’s the most consistent source of the highest quality wood. They manage each parcel of the forest very carefully.”

Then he paused for a moment. “But, pretty much, I learned most of what I know about cooperage from my dad.”

Considering Keith Roberts’ own career history and direct connection to one of California’s most famous wine families, his master cooper son’s choice of profession makes sense.

(To be continued in part two.)

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