Wooden casks (colloquially you would refer to them as barrels) are responsible for the magic in whisky. As you may already know from our article What is Whisky?, whisky is different from other alcoholic spirits due to the requirement to mature the whisky in wooden casks. 

Aging is what creates the golden-copper colour you see in bottled whisky. Aging is also what creates most (up to 60%) of the beautiful caramel flavour that you taste in whisky. 

Distillation is not the end of the whisky-making process. Notice that the resulting spirit is still completely colourless. It is only after several years of aging in a cask that whisky achieves its elegant golden-copper colour.

Yet, you wonder, why are some bottles of whiskies golden colour, while some other bottles darker red or copper colour? The answer lies in the type of cask used.

1. Ex-Bourbon Casks

Ex-bourbon casks are the most common cask used to make whisky, outside of the United States - if you are wondering what’s so peculiar about the United States, check out the Basics of American Whiskey.

These are second-hand casks that have been used to store bourbon whiskey, usually exported from America. Scottish distillers love buying ex-bourbon casks as they are relatively cheap. Ex-bourbon casks cause the spirit to take on a yellow-gold colour also impart a light sweetness to the whisky, with notes of honey, vanilla, caramel and cream.

Many whiskies (apart from American whiskey) would contain some component that has been matured in ex-bourbon casks. But certain bottles of whiskies are matured exclusively in ex-bourbon casks, depending on the preferences of the distillery.

Glenmorangie Distillery famously loves ex-bourbon casks. The distillery is aware that its spirit is very light-tasting, and would be better complimented by the subtler flavours imparted by ex-bourbon casks. This is why expressions from Glenmorangie tend to have a very light oak character with notes of some vanilla, creme brulee and cinnamon.

To read more about how their unique “giraffe” stills and how Glenmorangie whiskies get their unique character, check out our WhiskyDex article on Glenmorangie Distillery.

2. Ex-Sherry Casks

Ex-sherry casks are the second most common type of cask used to mature whisky. You guessed it: these are traditionally second-hand casks that have been once used to store sherry. Scottish whisky distillery learned that the dark, sweet remnants in the empty sherry casks could do wonders for their whisky. 

Ex-sherry casks cause the whisky to take on an amber red colour, and impart more intense sweetness with notes of dried dark fruits (such as figs, plums, dates, raisins, prunes and black cherries) and roasted nuts.

Certain types of sherry (particularly “fino” sherry) can also impart less sweet, but drier and more leathery aromas.

Ex-sherry casks have been associated with more expensive taste. Traditionally, Scottish distillers loved to use sherry casks to increase the luxe of their whiskies. That said, ex-sherry casks are about 10 times more expensive than ex-bourbon casks, and distilleries could not afford to use them on a regular basis.

One extremely famous distillery that loves sherry is Macallan Distillery. One reason is because Macallan’s spirit has a much heavier body, and can stand up well to full maturation in stronger-flavoured sherry casks. Expressions from Macallan therefore tend to be rich, full-bodied and contain sweet sherry notes of dried raisins and Christmas cake.

To read more about James Bond’s favourite whisky (Macallan, duh!), and how it gets its signature flavour profile, check out our WhiskyDex article on Macallan Distillery.

That’s not all!

Drinking whisky is enjoyable, but it is even more so when we understand how exactly our favourite whiskies are made. And there we are- the 2 most common cask styles of whisky that every whisky drinker must know. 

The world of whiskies is actually much more diverse than these two classic cask styles. Rum-cask Talisker anyone? Fancy a Pinot Noir-finished Ardbeg? Stay tuned to this space for more notes on other cask styles that are getting increasingly popular in the whisky world.

If you’d like a much more in-depth look into the history of whisky casks and how they affect the flavours of whisky, check out our article All About Casks.

@charsiucharlie