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How a Small Cask Affects the Maturation of Whisky

On cask sizes

Small casks next to bigger casks
Whisky casks at Dallas Dhu

How does using a small cask change the way whisky matures?

Let’s talk about sizes, geometry, time, and the answer to life, the universe and everything.

You’ve probably read that the industry standard, the bourbon barrel, has a capacity of 200 liters. And that sherry butts are much bigger, around 500 liters. Oh, and there’s plenty of other sizes with funky names like “hogshead” or “puncheon”.

To generalize and simplify a bit, we could say that most whisky brands we know will mature their spirit for 8-16 years in casks of 200 to 500 liters capacity. Roughly.

However, if you’re really into whisky, you may also know that some distilleries use smaller cask sizes. The Laphroaig Quarter Cask (125 liters) is probably the most widely known example of this, though there are many more, especially if you look at younger distilleries.

So why use a small cask?

It has to do with geometry. Remember the glorious days in school, calculating the surface and the volume of various perfect shapes, thinking this was the most futile exercise that year? I bet you didn’t think back then that you would connect that with booze one day, did you?

But in the whisky industry, geometry matters. You see, the smaller the cask, the more inner surface you have per liter of content. In other words, liquid put into a small cask will have proportionally more contact with the wood inside that cask. More wood contact means more aromas and more color. Easy as π.

No shortcuts

And now for the slippery part.

At that point, someone may have claimed that whisky “matures faster” in a small cask. In fact, some people may even have claimed that putting a stick of wood with notches in it will turn a cheap young whisky into “top shelf” liquid.

Hold on there, buddy. Let’s dig deeper:

Sure, in a smaller cask, the influence of the wood (and whatever was in the wood before you put malt spirit into the cask) will be larger. But here’s a not-so-secret secret:

Maturation is more than just wood influence.

Taking the time

Small enough to carry around.

When people ask me how whisky is made, I will usually explain at some point that time is the fourth ingredient. Malt, yeast, water and time. What does time do?

Obviously, the longer the liquid spends in the cask, the more time it has to extract aromas (and color) from the wood. But since you can also extract more by reducing the size of the cask, that’s not really the real influence of time. Over to chemistry:

There are chemical reactions that happen inside the spirit, whereby fatty acids slowly turn into esters. Esters are nice, they are responsible for the lovely fresh fruit aromas in spirits. Turning fatty acids into esters has the effect of turning a spirit that’s a little rough around the edges into something fruitier and “rounder”.

In fact, some white spirit producers will let their gin and their schnapps rest in the bottle or in tanks for weeks or months before selling it, just to give the spirit time to “settle down”. There’s no wood there, it’s all the chemistry of time and alcohol.

Designing the spirit for a small cask

So a longer maturation is always best, yes?

Well, like with so many aspects of making whisky, it’s a matter of compromise. When you distill, you can get more yield if you accept that your spirit will be a little rough around the edges. If you are going to put it in casks for 10-20 years, feel free to be rough and produce more: time will fix it for you.

But gone are the days where distilleries left and right could afford to forget about their casks for a decade or two. Especially not young distilleries like ours.

So if you don’t have that much time, the solution is to make the spirit smoother to begin with. And this is entirely up to the distiller, through the choice of ingredients and how when they make their heads and tails cuts. It’s not cheating, it’s a design decision, if you will.

Now to be clear, you can’t entirely simulate the effect of a long maturation. Nobody has solved that puzzle yet. That would be the holy grail of the spirit industry. If you’ve heard of quarter casks, you would most definitely have heard about it. But you haven’t, because it hasn’t happened.

The Small Cask Equation

So to summarize, there’s no real substitute for time, but it’s possible to require less of it to obtain a nice and smooth spirit.

Das Cask: your personal whisky, matured in a small cask.
This is not a cask. This is a Das Cask.

Hence, the equation we solve in order to make Das Cask boils down to this:

  • We want to use a small 30-liter cask because it gives you a more reasonable amount of whisky than a full bourbon barrel.
  • You may also not want to wait 10-20 years for your personal whisky. Maybe 4-5 is enough waiting.
  • Therefore, we have to make a spirit that is smooth and drinkable early on.
  • But because the wood influence will be large, it also has to be aromatic enough not to be overrun by the wood.

The answer is, of course, 42.

 

Photo “Whisky casks at Dallas Dhu” at the top of the article by Nilfanion (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons