Scotch & Sherry: From the Forests to the Cooperage

Originally published in Unfiltered #94
Words: Richard Goslan

The Scotch Malt Whisky Society goes to great lengths to ensure that we can trace the provenance and guarantee the quality of the casks we use for sherry maturation – and that includes being able to see exactly where the wood comes from, as well as how the casks are coopered.

It all starts in the woods. And a journey into a mighty oak forest that stretches from Galicia in the far northwest of Spain, across Asturias, on into the Basque country and then over to southern France. We’re heading into the Cantabrian mixed forests region, to find out more about the source of this Spanish oak for creating sherry casks in the company of Narciso Fernández. He’s the director general of Forestal Peninsular, which owns two sawmills in the north of Spain. He’s also the president of Tevasa cooperage in Jerez de la Frontera. Narciso’s business is all about oak, staves and casks. Lots of casks.

Into the woods

Along with Narciso, we head into the forests to find out more about how his sawmill works with Spanish oak to create the staves that ultimately go into making sherry-seasoned casks for The Scotch Malt Whisky Society. Narciso leads us deep into the forest, where a team is already at work felling oak trees, the treasured quercus robur. The trees are selected based on their diameter, around 60-70 centimetres, which makes them between 70 and 80 years old, sometimes older.

Seeing a tree being cut down obviously brings questions of sustainability. The forest is government-controlled and issues permits for a certain number of trees to be felled in specific locations. Companies such as Forestal Peninsular are part of the Programme for the Endorsement of Forest Certification (PEFC), which promotes sustainable management of the forests through independent third-party certification. Every tree felled by Forestal Peninsular will be issued with a certificate of sustainability by PEFC that shows the tree’s specific origin and demonstrates the legal and sustainable sourcing of forest products.

Regeneration of the forest is a completely natural process

“This space is approximately 20 hectares or more, and there are probably around 1,500 trees in this space,” says Narciso. “But it’s only possible to cut around 150, a maximum of 200 in a year. The other trees continue growing, and if possible we won’t cut here in this space for the next 15 or 20 years.”

Regeneration is also an ongoing and completely natural process. It’s forbidden to change the use of the forest in any way, for example by planting any other species of tree. As an oak tree is felled, acorns are scattered randomly and left for nature to take its course, in an area with enough space and light for its roots to start expanding – and beginning its own journey over the course of the next 70, 80 or 100 years.

“Our philosophy with the company is the same as my father’s when he founded it 70 years ago,” says Narciso. “We want to end our working lives with a better forest than when we started our work. We want our sons to have better quality, healthier forests, than I see today.”

Once the tree is down, Narciso’s team quickly engage in their various tasks. The foliage and branches are stripped off to leave a bare trunk, which is then grabbed by a huge claw on the ‘autocargador’ and hoisted onto its loading bay.

From one tree, it’s possible to cut between 100-120 staves. When you consider that a finished cask will be made up of 32 or 33 staves, that means that you only get three casks’ worth of staves from a single oak tree. The outer area of laburnum, or sapwood, contains a high level of moisture and has to be removed. Only the duramen, or heartwood, is suitable to be transformed into staves.

Narciso asks operator Benedisto Seren to hold the tree at an angle to demonstrate the amount of water pouring out of the newly sawn cut. Narciso explains how a tree in this condition contains around 70 per cent moisture, which we can see already dripping out of the trunk.

Richard Goslan and Euan Campbell at the sawmill in Galicia, where the logs will sit for between two to three months

A patient process

Ah yes…the flavour. It all comes back to flavour, and quercus robur has a distinct character that influences whatever liquid is left to mature in that species of wood.

“The region and the species of the oak are very important,” says Narciso. “With Spanish oak, quercus robur, the main character comes from the high content of tannins. These go on to produce special smells, special flavours and also more colour. The variety of sherry wine used to season the casks is very important, but it’s the tannins in quercus robur that bring more colour and those flavours of dried fruits, spice, nuts and chocolate.

“American oak, quercus alba, is lighter in tannins, and is immediately different both in colour and flavours. The colour is lighter, the flavours are fresher, with more vanilla, more apple, more yeast. Both wood types have their character, and both are capable of creating fantastic whiskies.”

To the sawmill

Next stop is the Forestal Peninsular sawmill near Lugo, where we get an immediate sense of the scale of their operation from the endless stacks of logs piled up in the yard, undergoing their first phase of drying before being ready to become staves.

Inside the factory is a blur of action and noise as a section of tree trunk enters at one end and is stacked up moments later as a selection of perfectly shaped cask staves. Narciso indicates what part of the log can be cut – it isn’t as simple as slicing it into as many sections as possible. Instead, the log is cut into quarters, sawing against the grain to prevent the cask from leaking when the staves are made into a cask. That further reduces the number of staves you can cut from any one section of tree, but is an essential part of the process.

There’s a combination of manpower and technology at work in the sawmill, as machine operators guide the wood through the series of saws, aided by lasers to ensure staves are cut to the perfect size from the appropriate part of the tree. It’s an endless hive of activity.

“In total we need 6,000 cubic meters of staves in the cooperage per year, to be able to create 24,000 casks,” says Narciso. “And for that you need nearly 20,000 cubic meters of logs.”

Euan and I step out to pose for some shots in front of a huge wall of oak, dwarfing us with its scale. Narciso says that judging by their diameter, some of these trees could easily be 200 years old. It’s a privilege to be up close to witness the journey they’re on – and one that we’re able to continue in Andalucía.

This, of course, is where the staves from these ancient oak trees will be transformed into sherry casks. At the cooperage, vast structures of staves are drying under the intense Andalucían sunshine, stacked up neatly as their development is monitored to ensure they’ve dried out to the point that they only contain between 12-14 per cent moisture.

Casks being toasted before being pulled into shape at Tevasa cooperage

Fire and water

Inside the cooperage, the first step is to build the basic structure, known as raising a cask, with around 30 staves fitted around a metal raising hoop, which keeps the top half of the cask in shape. The bottom part of the cask is left opened out, a bit like a badminton shuttlecock, before it’s wheeled into a shower to bring some flexibility back to the dried-out staves.

Then comes the fire. The coopers need to bend and tighten the lower part of the cask, so they position it over an underfloor oven fuelled with leftover oak and let the heat gently soften the wood further. While this is happening, they position a steel loop around the base of the cask, which gradually tightens to pull the staves ever closer together.

It’s a hot and seemingly dangerous business as the casks continually come and go, cables are stretched and loosened, and flames roar out from the top of the casks before being dampened back down with a dousing of water.

The casks are toasted rather than charred, as in the world of bourbon in the United States. The scale of toastingcan be specified by whoever’s going to end up using the cask in question, from light, medium or heavy, but couldbe for between 40 and 60 minutes at a heat of around 240-250 degrees centigrade.

Finishing touches

Following the toasting, the new casks have their heads fitted and some careful finishing, including sanding and the drilling of a bunghole. Once they’ve been tested as thoroughly leak proof, they receive the all-important cooperage branding.

It’s an exhilarating, noisy but perfectly choreographed environment, with skilled coopers – some from different generations of the same family – handling the casks with a familiarity and confidence that can only come from extensive experience. When you’re creating almost 100 casks every day, everything has to work safely and seamlessly.

“At Tevasa cooperage we build 92 cask per day, and when they leave here they are totally ready,” says Narciso.

“But they aren’t sherry casks yet, they’re only casks. Next, we need to send them to the bodegas in and around Jerez, where they will start the process to be seasoned with the sherry wine that the customer prefers – normally oloroso, or Pedro Ximénez, or it could be amontillado or manzanilla – it depends on the customer. And that part of the process could last from a year and a half to more than two years, also depending on their preference.”

Narciso does another quick stock take of the journey of these pieces of wood from the forests of Galicia to the point that they’ve become a cask, seasoned with sherry and then ready to be filled with whisky.

“From cutting down the tree to sending the cask between the cooperage and the distillery, we’re talking about a minimum of five and more often up to six years,” he says.

As with a good whisky – you simply can’t rush the process.

Unfiltered Magazine is The Scotch Malt Whisky Society’s premium whisky knowledge magazine delivering quality content exclusively to members in an immersive multimedia format monthly. To view Unfiltered #94 in its entirety (as well as all back issues), log in and access the members’ portal or join The SMWS today — the world’s most colourful whisky club.