There’s something unlikely about the pairing of Scotland and Andalusia – the fine single malts of Scotland’s craggy landscape being matured in barrels shipped from the warmth of Jerez, where orange trees line the streets. Together, however, the raw spirit and these barrels – drenched in the complex flavours of the Sherry they previously held – create something all the more special.
Today you’ll find spirits aged or finished in any number of casks – previously bearers of Bourbon, wine, Port, Madeira and more. Sherry casks are, however, the traditional choice – but why?
Well, largely thanks to the Scots’ penchant for Sherry. The fortified wines of this southern Spanish region have been savoured north of the border since the 16th century, although it was a trend for Sherry and rum punches in its clubs during the 18th century that really caused a rocket in sales. Doubtless this was tied to Scottish interests in Sherry, with bodegas in the hands of the likes of Arthur Gordon and George Sandeman (also of Port fame) .
At the time Sherry was – like most wines – shipped in cask, then bottled on arrival. These barrels wouldn’t be the ones in which the Sherry had been maturing (ie they weren’t part of the solera), but barrels explicitly made and used for transport, holding Sherry for a matter of months as it was shipped from Spain to its final destination. This kept the Scotch whisky industry well stocked with a steady supply of Sherry casks being delivered right to its doorstep.
And producers found that these barrels – thought to have absorbed as much as 10 litres of Sherry – delivered layers of complexity to the spirit that fills them, adding notes of dried fruit, nuts and sweet spice. Of course the sort of Sherry that filled the barrel impacts the style of the final whisky. Biologically aged styles – Fino and Manzanilla – are rarely used, while the nutty, spice and dried fruit notes of Oloroso are the most common choice. Pedro Ximénez or PX – the lusciously sweet, almost treacle-like style of Sherry – lends the richest notes to a whisky.
Gradually, however, regional bodies around the world started insisting wines were bottled at source to protect their wines from possible adulteration. And so in the 1980s, the death knell almost sounded for Sherry-cask-aged whisky, as it became illegal to transport Sherry in cask. This, paired with Sherry’s fall from fashion and therefore decreased production, made Sherry casks rare beasts.
But – to the relief of whisky-lovers everywhere – the industry found a solution. Today, the production of Sherry casks for the whisky industry has become a second avenue of income for Sherry bodegas. The barrels are filled with Sherry with the sole purpose of flavouring the cask – either at the bodega in Jerez, or in Scotland (having shipped the Sherry over).
Technically, there’s no definition of “Sherry cask” under Scotch whisky regulations. While casks have to be made of oak and hold no more than 700 litres, the rules don’t specify how long a cask would have to hold Sherry for the term to be used on the label. In fact, at present, the casks don’t in fact have to hold “real” Sherry – and as a result much of the fortified wine used to season casks is from beyond the borders of the Sherry triangle.
“True” Sherry casks are in high demand. Today they can fetch as much as 10 times the price of a Bourbon cask. Given their expense and rarity, it’s no surprise that producers use these casks many times over. However, with each use the impact of the Sherry flavour is reduced – meaning that “first-fill” casks are all the more special.
With such a long tradition, Sherry-cask-aged whisky isn’t going anywhere – but it’s certainly getting harder to find.