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What is the difference between a cognac barrel and a whisky barrel?

Cognac and whisky tend to be aged in oak wood barrels during the maturing process and it’s precisely this stage following the distillation, that gives the spirits their unique aromas, flavours and sumptuous colour. Cognac though, unlike whisky, is matured only in barrels dedicated to cognac but it’s a different story with whisky, which can be matured in ex-sherry, port, sauternes or bourbon barrels, letting the spirit soak up those divine remaining aromas.

Why are cognac and whisky aged in casks? Well, it’s actually quite straightforward. It’s during this ageing process that the spirit is infused with flavour, bringing a delightful, unique complexity to each barrel. Over the centuries, these traditions have come to be set in stone with their own formal rules. For instance, cognac has to have been matured for at least two years, giving it the qualifier ‘VS’. If matured for four years, then it’s qualified as ‘VSOP’ and ‘XO’ for six years. Scotch whisky on the other hand, requires a minimum of three years' maturation in order to be defined as whisky.

However, you can’t mature spirits in just any cask. It might look simple but a lot of work goes into finding the right casks, hewn from the right wood and crafted in the right way.

Oak wood is usually the number one choice for casks used to mature whisky and cognac because of the way the spirits interact with the material. The mysterious aromas in the wood, whether new or used, vary widely in different types of oak. This means that choosing the right wood is half the battle and has become a real art in its own right. The wood’s origin, age, thickness, texture and toast are crucial to the master blenders of each house as they also predict how the original character of the spirit will change and express itself once it soaks up the surprisingly smoky, spicy and fruity flavours locked in the oak.



Cognac is matured only in dedicated cognac barrels, i.e. new barrels made especially for cognac maturation. At Hennessy, all eaux-de-vie are aged according to age-old traditions in handmade French oak casks.

The wood used for making Hennessy barrels comes from two main sources: the Tronçais and Limousin forests in France. The former’s soft tannins and the latter’s balanced strength are very desirable characteristics for cognac-makers. Limousin oak is particularly prized for its rich and creamy vanilla aroma.

Hennessy’s own barrel cooperage, the Tonnellerie de la Sarrazine, is a colossal collection of almost 350,000 barrels. The Tonnellerie has been making casks according to an expertise passed down from generation to generation for no less than 250 years. During the life of an eau-de-vie, old or new cognac barrels may be used depending on the flavour profile that the master blender wishes to impart into the spirit.


It is possible to use barrels over and over again when maturing whisky. At Glenmorangie however, each cask is used only twice, which is a way of ensuring maximum flavour and creating that coveted round, smooth taste. The result for Ardbeg is three core expressions of single malt whisky that are renowned across the world as arguably the peatiest, smokiest, most powerful and complex single malts you can get.

Traditionally, Scotch whisky-makers prefer used, ex-bourbon American oak casks for the flavours they impart, rather than the brand new casks favoured by cognac makers. Glenmorangie and Ardbeg use ex-bourbon casks for their signature Original and Ten-year-old labels, as well as most of their other single malts. At Glenmorangie, they go to great lengths to find the right ‘bespoke’ ex-bourbon cask, which will impart some of the spirit’s trademark flavour. The team has travelled the world for over three decades, seeking out casks that yield intriguing layers of flavours.

Glenmorangie’s single malts can undergo a double maturation after their time in ex-bourbon casks, depending on what the master blenders deem necessary to obtain the perfect blend and expression for each whisky. Not all the spirit undergoes the same treatment each time: for example, most of Glenmorangie Grand Vintage 1990 is matured in ex-bourbon casks and only a portion will be aged in ex-sherry casks.

You can taste the nuances of each cask’s influence by tasting Glenmorangie’s Quinta Ruban, Lasanta and Nectar d'Or These single-malt whiskies are first matured using a wide range of ex-bourbon casks for ten years before each is matured for an extra period in different, hand-selected casks. Ruban undergoes its extra maturation in Ruby Port casks from Portuguese Quintas, for the smooth, exotic taste they impart, while Lasanta goes through Sherry butts for a full-bodied, rich and nutty taste that can sometimes even be sweet. Nectar d’Or undergoes its extra maturation time in the finest Sauternes wine casks from France, for the luscious, vibrant taste obtained. What all this shows us is that there is no set formula – and that’s the magic of making whisky!

Who knew that so much work went into the choice of casks for both whisky or cognac maturation and that casks were so important for obtaining the perfect flavour? Just like wine, the process is a fascinating centuries-old story of tradition, expertise and innovation, expressed through a fastidious cask-selection process. It is the tale of rare talent bestowed upon a select few men and women whose imagination and creativity form the basis for the unique tastes of the world’s finest spirits.