The cask makes the whisky, with the vessel’s previous contents playing a vital role in the quality of the spirit that ends up going into the bottle. But what kind of casks can distillers legally use? Angus MacRaild casts his eye over how the rule book has evolved

As whisky production in Scotland took its tentative steps out of infancy, it did so hand in hand with the cask – a wooden, coopered vessel in which new spirit, over time, was found to be enriched, softened and improved to a point of almost miraculous palatability.

The process of discovery is often romantically thought of as an evolution of serendipitous pragmatism, whereby casks used for transport were left, for whatever reason, only to yield an improved content. In reality it was almost certainly an inevitability, as the beneficial nature of cask maturation was already known by wine makers in Europe since at least 500BC. That knowledge was certain to eventually spread north to the fermenters and distillers of grain.

Whisky owes the wooden cask a great deal. However, it is only in recent decades that there has been a tightening of the laws surrounding what wood you can fill and why. The basic principles were defined in the Scotch Whisky Act of 1988, which stated Scotch whisky must be matured in a wooden cask not exceeding 700 litres in capacity. This was further refined by the Scotch Whisky Order of 1990 where the ‘wood’ was specified as oak. These decisions were arrived at as a result of consultation with the industry and research by the Scotch Whisky Association into what could reasonably be defined as ‘traditional’ cask types based on historical industry practice.

Further to this there are sub-categories of cask which are deemed acceptable for use in maturation or finishing. These guidelines were arrived at by the SWA in the early 2000s after they noticed a rise in the prevalence of the practice of finishing a whisky in different casks that would have formerly held a variety of different spirits and wines. Their research and consultation in the early 2000s yielded the following guidelines on permissible cask types under existing UK law:

“Bourbon and other whisky, grape brandy (including Armagnac and Cognac although they are technically wine spirits), rum, fortified wine (including Sherry, Madeira, Port and Malaga), still wine (of whatever type or origin) and beer/ale. If members wish to use any other type of cask for the maturation or ‘finishing’ of Scotch Whisky, the onus would be on them to establish that that type of cask had been traditionally used in the industry and to provide evidence to that effect. It is unlikely that a court would accept a particular type of cask as traditional unless there was evidence of significant use of that type of cask in the industry over a number of years. For example, Counsel did not believe the Association had found sufficient evidence of the use of Calvados casks in the past to justify their use for the maturation or ‘finishing’ of Scotch Whisky”

These very guidelines were recently quoted back to the SMWS when one of our bottlings – 35.178 – was released after a period of extra maturation in an ex-gin hogshead. The SWA in this instance disputed the historical use of gin casks (or indeed the maturation of gin full stop) and suggested it wouldn’t be wise for the SMWS to make a habit of using gin casks. There is indeed historical precedence for the use of chestnut casks in whisky maturation so a distiller might make arguments for its use again today – although, not being oak, it is unlikely to get very far.

Perhaps the most notorious story in recent years that illustrates the tension and necessary dialogue that exists between the SWA and whisky producers is that of Compass Box and The Spice Tree. The Spice Tree was a blended malt whisky which spent time in casks with ‘inner’ staves of toasted French oak, which John Glaser of Compass Box intended to add a herbal, spicy quality to the finished whisky.

The SWA objected to this practice on the grounds that it wasn’t traditional. Glaser’s solution, after consultation with the SWA, was to have specially coopered American oak casks produced with ends made of heavily toasted French oak. It’s a neat illustration of how there can often be creative solutions to problems or disagreements which arise. It’s also important to point out that the SWA do not seek confrontation, nor do they desire to get embroiled in legal battles. They want a producer to be able to sell products that everyone is happy with as much as they are tasked with protecting the ‘traditions’ and character of Scotch whisky.

Oak has overwhelmingly been the main wood type in which Scotch whisky has historically matured. And while there are varying species of oak, they all broadly possess similar, necessary properties. It doesn’t easily leak once coopered; it allows for even evaporation; it doesn’t impart unpleasant flavours to the distillate; it is prevalent enough to meet the demands of a large scale industry. Indeed, distillers such as Bill Lumsden of Glenmorangie have experimented with other wood types such as Brazilian cherry wood and found it sorely lacking. The fact that the SWA does not mind distillers experimenting with other wood types says a lot about the unshakable confidence people have in oak.

If a distiller discovers a new wood type that suits their distillate – which well they might, as the new Dornoch distillery plans to mature some spirit and gin in juniper wood casks – and wishes to bottle the results, the SWA is happy to work with them to see that the product can be released as a ‘spirit drink’. That’s provided the labelling, imagery and language do not infringe upon those of Scotch whisky.

So, there remains a small grey area where producers of Scotch whisky may experiment with cask type, provided they can prove that it has historical precedent in the industry. The guidelines exist to ensure minimum deviation from the established character and colour of Scotch (contrary to popular belief the flavour of any contentious whiskies are taken into account by the SWA).

While modern, small scale bottlers and distillers will no-doubt see this as a stifling of creativity, larger companies see it as a protection of Scotch whisky. Perhaps debates about wood are a distraction though. Ultimately, from the consumer’s perspective, producers already have the means to make incredible whisky within the existing legal framework and definitions.

Rather than attempting to deviate from that, why not push for the most distinctive and exemplary whiskies possible within existing definitions? Experimentation is only a success if it delivers true quality.