As far as job titles go, ‘master of wood’ is pretty hard to beat. “It looked great on business cards,” smiles Scotch whisky industry veteran Stuart MacPherson. “Some of my colleagues may have said it was more along the lines of ‘lump of wood’, though,” he adds with a self-deprecating laugh.
MacPherson spent 43 years at Macallan owner Edrington, becoming master of wood in 2012, a title that put him on par with the industry’s master blenders and master distillers. During his tenure, The Macallan became synonymous with whiskies aged in sherry casks, trumpeting its use of both American and European oak on its labels and in its marketing. One of MacPherson’s lasting achievements was building an audit trail that allowed The Macallan to trace the provenance of its casks from the forests in which the trees grew through to their locations in Scotland’s warehouses, via sawmills and cooperages.
He spread his wings in 2021 to become a consultant, including for Nine Rivers Distillery in China, and in 2022 was named master of wood at Ardgowan, a £20 million Lowland single malt distillery being built between Greenock and Inverkip, 30 miles west of Glasgow on the shores of the Firth of Clyde on Scotland’s west coast.
His first task was to commission Spanish cask maker Bodegas Miguel Martín to create “the infinity cask” — billed as the first unique Scotch whisky cask to be designed in more than a century. MacPherson specified every detail for the bespoke casks, from the species of oak selected for the timber to the temperature at which the wood would be toasted.
MacPherson and his Ardgowan colleagues are remaining tight lipped on the precise details of their casks, which will each cost between 30 and 40 times more than a standard off-the-shelf vessel, putting the total value of the deal with Bodegas Miguel Martín at £100 million. What they will say is that the casks are big — really big.
The 2009 Scotch Whisky Regulations dictate that the oak casks used to age the spirit cannot exceed 700 litres in volume, with the infinity cask “just” squeezing under that requirement, according to MacPherson. By comparison, bourbon barrels hold about 200 litres, while the casks found inside the sherry-producing bodegas or wineries at Jerez in southern Spain tip the scales at 600 litres, and the butts that were once used to ship sherry to the UK weighed in at 500 litres.
Since 1981, sherry has only been exported in bottles (precipitated by regulatory changes in Spain), and so a whole industry has grown up to produce casks for Scotch whisky distillers and other spirit producers replicating the size and shape of the old transport or export butts. Instead of carrying fortified wines across the seas, these casks are seasoned with sherry for a minimum of 12 months to receive certificates from El Consejo Regulador, the official body in Jerez that guarantees the provenance of both the sherry and its casks.
In contrast to the Scotch whisky industry standard of seasoning for between 12 and 18 months, MacPherson has opted for 27 months, with his casks being bathed in oloroso and Pedro Ximénez sherries at Sanlúcar De Barrameda, one of the three sherry-producing centres in the Jerez region.
Sanlúcar’s location on the coast mirrors Ardgowan’s position on the Firth of Clyde. Construction work began in October 2023 at Ardgowan — a privately owned 18th-century stately home, castle, and gardens — with the distillery due to be completed next year. Ardgowan’s team hopes Sanlúcar’s proximity to the sea will imbue the casks with a saline maritime element that will eventually be transferred to the finished whisky.
As well as taking over a cluster of estate buildings – including cottages, a disused sawmill, and former horse stables – Ardgowan’s main building will be a new 21-metre tall “cathedral of whisky”, designed as both a production facility and tourist attraction. Once it’s up and running, the distillery will have created 47 jobs in an area that still suffers from the industrial decline that saw the decimation of the River Clyde’s traditional shipbuilding industry.
The first batch of MacPherson’s casks have already been produced and are undergoing seasoning in Sanlúcar.
Once the casks are full of spirit, his next task will be to continue shaping Ardgowan’s wood policy, so that the distillery gets the most benefit from its expensive new toys.
“The way we looked at it at Macallan was that a cask was like a teabag, basically,” MacPherson explains. “The more you fill and empty it, the less extractives are going to be beneficial to that spirit — we tended to use a cask twice and then we would use it for other products within Edrington’s range.”
In broad terms, wood and spirit interact in three main ways: the spirit extracts flavours and textures from the wood; the wood removes impurities from the spirit; and compounds from the wood and spirit combine to produce further flavours. The more often a cask is used, the fewer parts of the wood remain chemically active to interact with the spirit.
“While sherry bodega casks might be 50, 60, or even 70 years old and will have an initial impact on the spirit, when you look at longevity and the investment and commitment involved then you really want a new cask because you get more interaction between the cask and the spirit,” MacPherson adds. “That’s why we’ve gone down the route of commissioning these bespoke casks.”
Once Ardgowan has begun production, MacPherson will continue to work with Max McFarlane, the company’s master whisky maker, to assess how the distillery’s new-make spirit will marry with the wood. An Inverkip local, McFarlane worked with MacPherson at Edrington, and has created the Clydebuilt range of blended malt and single grain whiskies to generate interest in Ardgowan ahead of the launch of its own whisky.
The long 27 months of seasoning for the casks is reflected in the Ardgowan team’s other choices — “slower and longer” could be its mantra. Many start-up distilleries in Scotland have opted for smaller casks to increase the amount of spirit coming into contact with the wood and thereby bringing their whiskies to market more quickly, but Ardgowan’s giant casks mean the interaction between the wood and spirit will be slower — its first whisky is expected to slumber for seven years before being bottled.
Its average fermentation is expected to be a lengthy 72 hours, with 11 fermentations taking place each week. In the initial phase, a 12,500-litre wash still and a 9,000-litre spirit still will be installed – both being made by coppersmith McMillan at Prestonpans near Edinburgh – and fed by six washbacks and a five-tonne mash tun, delivering just shy of one million litres of pure alcohol annually. A second set of stills will then be added along with another accompanying half-dozen washbacks, doubling the distillery’s output to two million litres.
Like many of Scotland’s new-wave whisky distilleries, Ardgowan also aims to minimise its impact on the environment. The site for the distillery sits on the edge of Clyde Muirshiel regional park next to Kip Water, a small river. The company is working with Heriot-Watt University in Edinburgh, McMillan owner Briggs of Burton, and technology developer Hydrogen Green Power to create a system to capture the carbon dioxide produced during its fermentations and turn it into methane gas, a feat not yet achieved by any Scotch whisky distillery.
The stills are likely to be heated using mains gas initially, but the distillery is eyeing a switch to hydrogen within 18 months, if current trials at other sites prove that the technology is feasible. Either way, Ardgowan also aims to feed its byproducts into an anaerobic digestor, a sealed container in which bacteria break down natural materials to produce methane, the same fuel found in mains gas.
That same focus on the environment is also reflected in MacPherson’s nascent wood policy. “It’s only what we call the ‘heartwood’ of an oak tree that’s used to make casks – that’s only about 25 per cent,” he explains. “Forest management is tightly controlled by the governments in France and Spain, but it’s still important to get the most out of your investment in those casks because they’re a precious resource.”
While MacPherson has made his name in the Scotch whisky industry, it could have all been so different. Another career beckoned when he was at school: becoming a physical education (PE) teacher.
“I did a lot of athletics as a teenager,” he remembers. “I was a middle-distance runner, 800 metres and 1,500 metres, and quite a good one. I had a summer job working in a cooperage with all intentions of going back to school to become a PE teacher. But I got quite fascinated with the art of coopering.”
That fascination led to him accepting an apprenticeship in September 1979 to learn coopering, or barrel making, at the Clyde Cooperage in Glasgow, which was owned by Robertson & Baxter, the forerunner of the modern Edrington Group. The cooperage moved to Lochwinnoch in the 1980s and then to the North British Distillery’s Addiewell site in the early 2000s.
Running’s loss was whisky’s gain. Swapping being a master of the track for becoming a master of wood has allowed MacPherson to leave a legacy, not only at Macallan but now at Ardgowan’s fledgling distillery, too.
