The screech of wood meeting an industrial planer blade pierces the air. One by one, rectangular boards a meter in length meet their fate, emerging from the machinery just a bit more trim and shapely. A few meters away around a corner, huge balls of fire burst to life and subside, leaving behind the evocative smell of charred wood. The background accompaniment to the theatrics is the constant, arrhythmic clanking of metal hitting metal, hammers striking bands of steel. The scene is worlds away from the calm serenity that wine and spirits markets strive to convey in promoting their products.
Outside, it’s a sunny, blue-sky February morning in Jerez de la Frontera, Spain. Federico Sanchez-Pece Salmerón, the director of Communications for Grupo Caballero, has brought us to the Antonio Páez Lobato cooperage, one of several that supply sherry producer Lustau with newly made casks for their sherry wines. The casks being constructed mere inches from us will soon hold sherry, but won’t reside in a place of honor within a sherry solera. Rather, their final destination is far away from Andalucia, where they were born here in the southwest of Spain. But we’ll come back to that later.
When you dive headlong into the world of aged spirits, terms like ex-bourbon, American oak, French oak, first fill, and char-level fill your consciousness. Every ounce of aged bourbon, single malt Scotch whisky, aged tequila, or fancy rum has spent time in a cask which once was just a collection of new wood staves in a stack somewhere. Bourbon regulations, for example, require that anything sold as bourbon must be aged in new oak casks, having held no other spirit previously. Once the bourbon has aged, that cask can’t be used again for bourbon. Yet other spirits like rum, Scotch whisky, and tequila have no such restrictions, so producers of these sprits happily buy all the once-used bourbon casks they can get their hands on. Thus, American distillery names like Heaven Hill or Maker’s Mark are found on barrel heads in aging warehouses all over the globe.
A lesser known but equally important story involves Spain’s sherry casks, which also frequently migrate thousands of miles from the bodegas where they first held sherry. For centuries, the British have been profligate consumers of sherry (think Harvey’s Bristol Cream, for example), shipped to the UK in casks prior to bottling. Naturally, with all these sherry casks arriving in the UK, and in particular Scotland, the Scotch whisky industry began using the emptied casks to age their product. Naturally, the many liters of sherry naturally remaining in the cask’s wood (even after emptying) influence the whisky’s flavor profile. In fact, the Oloroso sherry influence is one of Scotch whisky’s hallmark flavors. While not every whisky producer uses ex-sherry casks, a number of producers are famous for their sherry-influenced profile (aka “sherry bombs”) including The Macallan, Glendronanch, and Glenfarclas.
It’s important to understand that casks used for aging Scotch whisky and other spirits aren’t randomly ripped from a solera to be sold off. The casks in a solera are a highly prized, integral system and may be used for a hundred years in some cases. After thousands of liters of sherry have passed through them, the wood becomes relatively “neutral” and no longer imparts strong flavors like vanilla, as a new cask would. Instead, the “sherry” casks used for aging spirits have typically held sherry for only a few years and never spent time in a solera.
A few decades ago, Spanish sherry producers began bottling sherry themselves rather than sending everything direct to the UK, and the flow of sherry shipping casks to Scotland all but dried up. However, the Scotch whisky producers have well-established flavor profiles, and those profiles require using sherry casks. Out of this necessity was born the idea of “sherry cask seasoning,” wherein Spanish cooperages and the sherry houses collaborate to build casks, fill them with sherry (typically Oloroso), and then store them in a warehouse for two or three years. Once emptied, the wet “seasoned” casks are shipped to the eager buyer. For instance, while in Jerez, we learned that The Macallan purchases seasoned sherry casks from Williams & Humbert. As for the sherry that had been in the casks, it may be used for a few more aging cycles. Eventually, the seasoning sherry is distilled to extract the usable ethanol or made into prized local Jerez sherry vinegar.
Arriving at the Antonio Páez Lobato cooperage, through a motorized gate and parking outside a nondescript metal building that reveals nothing of what goes on inside, we’re met by Isaac Páez, the third generation of this family-run enterprise – his grandfather started it in 1956. Federico translates for us as Isaac explains the vast stacks of wooden staves, stacked in alternating directions, outside of the cooperage building. Staves are stacked in this particular configuration to allow maximum air flow between them as they dry in the Spanish climate, a combination of hot summers and rainy winters. This is the only cooperage in the region that dries all their wood naturally, rather than using ovens to accelerate the drying process.
Most of the wood used here is European oak from Romania and France, although they sometimes use American oak when requested. Over the course of many months, the rain washes away much of the tannins, and Andalucia’s annual 320 days of sun dries them out. Two hundred truckloads of staves arrive here every year. When it first arrives the wood is around 30 percent humidity. By the time it’s air-seasoned and ready to use, the humidity has dropped to 16 percent. Over the course of a year, the cooperage uses the €8 million worth of wood (about 8,000 cubic meters,) to construct approximately 22,000 casks, at the rate of one hundred per day.
Entering the cooperage, we come face to face with yet more stacks of wood. The last thirty days of air drying must be done under cover to prevent them from getting wet. A pair of workers feed the roughhewn staves through a large power planer, giving them a slight angle on their sides and allowing them to form a circle when arranged side by side.
Nearby, the initial form of a cask springs to life. A team of workers coordinate to position 35 staves upright in a loose circle, held together at their top by a metal hoop, several feet in circumference. The resulting shape resembles a stubby, inverted funnel. A second hoop goes on a little lower on the funnel. The workers hammer down the hoops to make sure they’re tight and that the whole arrangement can be rolled to the next stage – fire!
In the adjoining open room, the nascent cask assembly is baptized with fire and water. In one corner, several casks soak underneath a shower assembly. Steps away, fires burns within four casks lined in a row, charring the wood inside. The fuel for the never-ending fires is scrap wood left over from other stages of cask construction. Occasionally a worker suspends a metal plate over a cask with a fire within, accelerating the charring process. Roughly every five minutes, a worker rolls one of the casks underneath a vent hood, and soon a giant plume of flame erupts up through the top of the cask assembly. The open-air room is noticeably warm on a chilly February day—one can only imagine how this job feels midday on a brutal Spanish August afternoon.
With the combination of moisture and heat, the staves become pliable enough for the non-hooped end to be constricted to the same dimensions as the already-hooped end. After a hoop is applied here, the cask has its near final-shape, after which it goes through yet more fire treatment.
As the charring takes place, the workers are constantly in motion, circling the casks, adding hoops and hammering them snuggly into place. These aren’t the final hoops – they just temporarily hold the cask in shape as it progresses through various stages. On the far end of the room, six menacing metal arms rise up out of the floor. After positioning a cask inside the arms and a hoop appropriately placed, hydraulics pull push the hoop into place.
By this point the cask resembles its final form, albeit without its circular ends. From here, it moves to a machine that slowly spins the cask, trimming and beveling the ends, and cutting grooves for the cask head to squeeze into later.
At another nearby station, a worker—all men, most from their early twenties to mid-thirties, and very few older than fifty–carefully arranges a series of shorter staves side by side, making a crude but highly efficient square. He’s laying out pieces that will soon form a cask head. After aligning everything just so, he uses a large compass to ensure a perfect circle can be cut. Another worker then separates the planks, inserts double-ended nails, and pushes them back together with a hydraulic press, thus forming a single, rigid square piece. A pass through a circular saw and some beveling, and a new cask head is born!
It’s fascinating to watch workers wrestle the wooden casks ends into the grooves cut at each end of the cask. First, the hoops on both cask ends are removed, allowing the staves to release just enough and the end piece to be inserted into the cask body. (Hoops in the middle maintain the basic cask shape while this is happening.) The cask ends are inside the cavity, and the worker uses thin metal tools to pull the head into place within the groove—a seemingly impossible task, even as you watch it happen in front of you. Afterward, the cask ends are re-hooped, pressing the cask-ends snugly into place.
But wait – there’s more. The nearly finished cask has a beauty appointment with a giant belt sander. While the cask rotates, a worker moves the belt sander along the cask’s length, smoothing the exterior walls. The center hoops were removed prior to this stage, leaving only the final end hoops to hold the cask shape. To my untrained eye, cask construction seems like a never-ending process of pounding hoops into or out of position.
The final hoops take their place on the cask via another multi-armed hydraulic device – a futuristic, sci-fi octopus with stubby metal arms descending from above. Unlike manually added hoops which are hammered into place, this hydraulic device smoothly and quickly positions each hoop in its final location in the blink of an eye—one of the few mechanized tasks in this room of fifty-plus craftsmen.
At last, the cask is done, but testing remains. While they may look watertight, newly made casks can leak — sometimes along the seam of two staves or through an invisible channel within a stave. Testing is low-tech, but effective: A few gallons of water go in, and the cask is then pressurized with air. After a few minutes, any leaks should be visible – the wood will be wet. Tiny leaks can be fixed with something akin to an oak toothpick pounded into place.
Finally, the cask is deemed worthy to use. The cask ends are branded with the cooperage name and the brand of the customer. These particular casks are destined for John Jameson & Son, the famous Irish Whiskey maker. Issac mentions that these casks are a special project for Jameson, who wanted casks of a particular dimension and capacity to fit their aging facilities: By making the cask shorter and wider, the cooperage was able to maintain the capacity of a normal sherry cask, while meeting Jameson’s size requirements for maximum aging capacity.
The final quality control check for these casks won’t happen for several more years. After the Oloroso sherry has done its magic and transformed the cask’s wood, the cooperage checks once more for any leaks and performs any needed repairs before sending the casks off to the Emerald Isle or points beyond.
While we’d been suitably impressed by cooperages in Scotland, our time at Antonio Páez Lobato was a far more immersive experience. Being inches away from the workers, the fire and the heavy equipment made my understanding of cask construction much more visceral and gave me even more respect for the people who do this rigorously demanding and precise yet mostly hand-crafted work every day.
Mrs. Wonk and I wish to extend our sincere gratitude to Isaac Páez, Lustau, and Federico Sanchez-Pece Salmerón for their time and generosity in making this deep understanding of sherry cask production possible.