Try a handful of whiskies these days and you're more than likely to have a number in that selection which will have spent some time maturing in ex-sherry casks. From Macallan to Glenfarclas, Yamazaki to Jameson, the tradition of using casks which previously held sherry is a long-standing one. But, as whisky manufacturers increase production and need ever more casks, there is talk of supply chain issues, of sherry producers not being able to keep up.
What's key for the whisky maker? Having a strong relationship with a bodega where you can trust the quality of casks coming to you for use in maturing your spirit. It is this relationship I witnessed on a recent visit to José y Miguel Martin (J&MM), a family-owned sherry producer in the dusty hills near Huelva in the south west of Spain, which provides all of the casks for the similarly family-
At the factory, tractors of all shapes and sizes queue in the dusty, sun-soaked yard, ready to disgorge their brimming loads of green and white Palomino and Colombard grapes into a juicy and pulpy pit - it's an incredible sight to catch, and one that only happens for around six weeks each autumn.
This contrasts highly with the scene inside the next-door building, the final destination for these grapes. While it is traditional looking farmers driving mismatched tractors that mesmorise bystanders outdoors, indoors it is the 200,000 litre stainless steel fermentation tanks that create awe - the old world and the new, combining together to show the sherry industry is not just about old dusty casks in dank warehouses, but is also a very slick and modern operation.
The main factory at J&MM - initially assaulting on the senses with a smell of chlorine from freshly cleaned floors - is not how one may picture the world of sherry but it is part of the reality for a prosperous operation such as this one. In the tanks, the juice from the pulped grapes that arrived from those farmers will ferment naturally for varying quantities of time before neutral grape spirit is added to the mix to stop natural fermentation and increase the alcohol levels.
While certainly not the full operation for J&MM - there is also a major on-site cooperage, expansive yards for drying staves, three other stainless steel tank filled warehouses, traditional solera system maturation warehouses and a vinegar factory - this squeaky clean space is the first link between the sherry and whisky industries, for it is the Oloroso maturing in those fermentation tanks that will go on to season casks used by whisky producers.
For J&MM this link-up is essential: over 50 per cent of its business comes from providing casks to whisky producers such as Glenfarclas, who it has worked with for nearly 25 years.
"At the moment there is a shortage of wood in the industry. So having the relationship with J&MM is essential - strong relationships are everything in this industry and it is a real challenge for the whisky industry because there are simply a finite number of casks out there," explains George Grant, brand ambassador and sixth generation of the family that owns Glenfarclas.
But this potential shortage of casks is not for lack of trying from the manufacturer's perspective. Recognising the potential risks in supply chain constriction, J&MM bought shares in sawmills in the north of Spain and in the USA so that production could continue at its on-site cooperage, where between 85-100 casks a day are made by hand. Three other nearby cooperages also make casks solely for the sherry producer.
To understand the process, owner Miguel takes us to an expansive, sunlight filled lot, where row upon row of American and Spanish oak staves are drying in stacks. Here the Spanish oak will air-dry for a year to 18 months, while the American oak staves will remain for three to four years.
The company currently has a 60/40 split of Spanish versus American oak in its supply chain, and Miguel explains that while many people only associate sherry casks with European oak, it is not always the best wood to use.
"European oak is much more porous and is not necessarily better - it is different. We would never mature Fino sherry in European oak because the wood is too rich in tannins," he says.
Inside the next-door building, those staves are sanded and shaped by experienced coopers, before being placed inside the metal hoops that will hold them together.
From here, the coopers roll the half-finished barrels over top bursting flames, which shoot out from gas cylinders in the floor. Thick ropes connected to pulley systems are wrapped around each barrel and pulled tighter and tighter to help mould the barrels as the flames toast their insides.
Once cooled, the newly formed casks will be filled with Oloroso sherry - made on-site in those large fermentation tanks - and left to season for five months. The Oloroso can be used up to four times before it is transferred to the company's vinegar factory.
As we finish up our visit around J&MM, I am struck by the fact the
process almost seems like a production line. While all done by hand at this family-owned business, it is clear there is pressure to keep up the fast rate of cask production to service an industry thousands of miles away. As Miguel explains: "Seasoning casks for the whisky industry doesn't help in the production of any sherry product. Both Oloroso and PX sherry, as products on their own, need old casks to mature in. So the process of seasoning casks for Scotch whisky is a totally different system of quality than creating a solera system for sherry production. Seasoning casks is only for the benefit of the whisky which will go into those casks."
It leaves me wondering how long it will be before the balance tips from sherry producers making a majority of casks and product for sherry, into a system where the sherry is produced just to service the appetite of the voracious whisky industry.
I will definitely be mulling this over the next time I enjoy a rich glass of ex-sherry cask matured whisky.