the whisky lounge - a journal tracking a whisky maturation project involving a newly-acquired oak cask and a significant amount of patience

Monday, January 28, 2008

A Wrinkle In Time

So, in spite of my best efforts, I learned something over the last few days. It happened because I was curious to find out what the difference in the surface-area to volume ratio was between my 1-litre cask and a generic 200-litre cask. My goal was to figure out how long to leave the whisky in the cask to get ten years' worth of maturation.

Last Thursday, believe it or not, I went on a quest to find a mathematician. I happened to be fortunate enough to find Dr Jonathan Scott, a world-renowned topologist currently based here in Ottawa. ("Topologist," by the way, is fancy math-speak for someone who studies surfaces. Don't worry - I don't fully understand it either) I described the situation to the good doctor, and he said he'd have a think and write me back with an answer.

In the interim, reader Will wrote in with his own solution to the question and posted it in the comments of this blog. A couple days later, Dr Scott wrote me back and confirmed that Will has mad math skillz: they both got the same answer.

Their answer was that the increase in the surface-area to volume ratio was approximately fivefold in the smaller cask. This means that I can expect ten year's worth of maturation in about two years. Yes, that's right: years, not months.

Is this a problem? I don't know. I'm a very patient man, but I'm also a remarkably thirsty one.

So I had a think. I remembered that the purveyors of the Whisky Works kit I purchased suggested the whisky would be sufficiently matured after a few months. I also remembered the website that reader Alex pointed me at which claimed that one could expect 1 to 1.5 years' worth of maturation in 1 month when using a smaller cask.

Now, I'm no math whiz, but I do understand that ten years' ageing in two years is the same as five years' ageing per calendar year. Which is (5 virtual years divided by 12 calendar months) 0.4167 maturation years per month. I'm pretty sure that 1 to 1.5 years per month claimed by the barrel and whisky merchants is not the same as 0.4167 years per month calculated by our resident math geniuses.

So what in tarnation is going on here? I can only estimate that there are additional factors at play in the speed at which whisky matures: it cannot be solely barrel size or else the mathematicians and the coopers would be in agreement. But it didn't solve my problem: why can't anyone tell me how long to leave the whisky in the cask until it's at least as mature as a 10-year-old scotch?

And so, much like an ancient Athenian supplicating himself before the prophetess at Delphi, I found myself turning to the greatest source of wisdom our age has to offer: the Internet.

What I learned was this: the age of a whisky, while of interest, is also far too little information to really be of any real use. It's true. Here's why:

Some distillers will age their whisky in unmodified 55-gallon bourbon barrels. These are just over 208 litres. Some distillers will modify these barrels by adding extra staves to bring them up to 250 litres, which will have the effect of slowing down maturation due to the lower surface area to volume ratio. However, sometimes distillers will insert staves running right through the middle of the barrel, thereby increasing the ratio and accelerating maturation.

Whisky is also frequently aged in sherry butts which hold an astonishing 500 litres, and therefore make their contents mature very slowly. Also frequent is the use of hogsheads which are 250 litres, but a slightly different shape than the modified bourbon barrels.

Also, and perhaps most importantly, whisky is moved from barrel to barrel over its maturation. think of "sherry finish" whisky. It starts in a barrel that didn't hold sherry (most likely a bourbon barrel, modified or otherwise), then gets poured into a cask that did contain sherry, which might or might not be the same volume as its first cask.

With every distillery using their own maturation methods for their own ranges of products, it's not really feasible to declare that a 10-year-old scotch from distillery A is anywhere near the same maturity as a 10-year-old from distillery B. Unless you know the entire history of the spirit that ended up in your bottle, you can only use its age as an estimate of its maturity, not a concrete indicator.

The end result for me is that there isn't really a target date for the removal of the whisky in my cask. I will never be able to say that it's had the equivalent of 10, 15 or 18 years of maturation at any point because those numbers mean different things to different distillers (and even to different whiskies from the same distillery).

The way this shakes out is that my whisky will be ready to drink on whatever day I take out a sample, have a sip, and decide that it's so good it deserves another round.


Will said...

Ian, your plan is a perfect one. Let us know how it goes!

One idea I had is to pick up more than one cask, and age the whiskies simultaneously. That way, you can sample the aging whisky as desired, and still satisfy the part of you that wants to leave it in for just a few more months... :)

Also, glad to know I didn't screw up the calculations. :)

butephoto said...

I've been thinking some more on what whiskies to try out in this, and I'd be really tempted now to try some of the young Ardbegs that just came out to see what I could do to them compared to the 10yo coming out later this year...



Barry Stein said...

Hi Ian,

We have been following your blog with great interest. Although we have heard from others about their experiences so far, your blog is by far one of the most detailed and fun threads we have encountered. We would like to comment on your aging issue. My partner in crime here also did the math (he has a degree in Engineering) and came up with the same ratios as your other readers. However, we still feel that our one week = one year ratio is somewhat valid. The reasons being, we do not feel that the size ratio is necessarily linear, which means there are other factors involved. First, this is a new oak cask. This will increase the maturing process because more of the wood flavour and char will be transfered to the whisky, as it is with bourbon or rye which both use new wood and generally only stay in the barrel for a few years. Second, we have found that in general maturation is not a straight line but occurs very quick early in the life of a whisky and then slows as it gets older unless the whisky is moved to a different barrel for finishing, which jump starts the maturation again. The same is true for the small cask, the first few weeks are dramatic, then the maturation slows. The last point we want to raise is that the "angels share" ratio also increases with the small cask and perhaps more so than maturation because the wood is thinner. Canada is not Scotland, especially at this time of year and depending on how dry your home is you will notice evaporation. We have told other purchasers that they should sample a very small amount of the whisky each week and when they like the nose, taste and finish and feel that the flavours have married nicely, then it is time to drain the cask and start over. It really has less to do with what the potential age the whisky might be as with the taste of the whisky. We have found that six to eight weeks is a nice time frame.

We look forward to continued good reading.


Barry Stein
Premium Bottlers Inc.

P.S. The LCBO does list the product as discontinued because it is a seasonal purchase. We hope to be back next year with new Whisky Work varieties. If you and your readers like the product let the LCBO know as this will help with their buying decisions.