From quarter casks to hogsheads to Sherry butts, what does it all mean and what difference does it make? Bourbon, American or European, Port, Mizunara… what? First fill, re-charred, virgin… huh? Isn’t a cask just a cask no matter what you call it? Well, no, actually. It can be daunting but we’re gonna help you out with that. Today’s post is focusing on casks sizes and we’ll get to some of those other things in other posts in the near future.
To start, let’s talk about why barrels are used for aging all kinds of stuff. In a word… character. The oak, the char, and the previous contents — if any — all add significantly to the flavour and colour of a whisky. The size of a cask can determine the amount that the wood will interact with the spirit stored in it. A smaller cask will generally have more interaction with the spirit and a larger cask, because of the greater amount of liquid will have less interaction and a subtler effect on the spirit.
So, let’s look at cask sizes. The standard bourbon barrel holds about 200 litres of whisky. Why are we talking bourbon barrels on a Scotch site? Most Scotches are finished in ex-bourbon barrels because these casks are so readily available and cheaper. Because bourbon, by law, must be aged in virgin (brand new) oak, there are plenty of ex-bourbon barrels available for Scotch distilleries. In other words, once an American oak barrel has been used to mature a bourbon, it can not be used for bourbon again so it’s sold to a Scotch distillery which may use it many times over as a refill cask. Lots of the vanilla and caramel flavours savoured in a Scotch come from these whiskey barrels. So let’s just say that the standard American whiskey barrel holding 200 litres is our baseline as it is the world’s most common.
Let’s go up from there. The next size up would be a hogshead which holds about 250 litres of whisky. As the casks get larger, there is going to be less interaction between whisky and wood so the cask influence on the whisky will be lessened. This may allow for a much longer bulk aging period for a Scotch before moving some expressions to finishing casks with a lot more character and iteraction. From the hogshead we can move up to a port pipe holding about 350 litres and then a butt which is around 500 litres and often used for sherry. A puncheon is upward of 500 litres and is used for a variety of aging applications from sherry to rum.
Moving in the other direction, we have a quarter cask which is around 125 litres, or a quarter of a butt. Because of its smaller size, there is a much greater degree of interaction between the wood and the whisky so the liquid will pick up a great deal of character. These are really nice for finishing a whisky to achieve a particular character. Even smaller is the octave which comes in around 50 litres.
Though that covers the most common cask sizes found in whisky, there are a few other sizes that you may encounter. For example, a barrique which is used in French wine is slightly bigger than a bourbon barrel at 225 litres. Some barrique finished Scotches are really nice as they take on the character of a particular wine. A drum or a Gorda runs around 650 to 700 litres, and a Tun can be as much as 1000 litres and might be used as part of big blends.
So there’s an introduction to cask sizes. Look for some future posts where we dive into other aspects of whisky casks.
