In the last post we looked at how the Scotch Whisky Industry formed without oak and how this style was available legally as Whisky until as late as 1915. Now we are going to delve into the depths of maturation, focussing on the cask’s previous contents (this will give you a new outlook on where the flavours come from) as well as the different types of oak and even different cask sizes and their effects. Not to mention the unquestionable skill and craftsmanship of the cooper.
I’d like to draw on all of my experiences over the last 8 years and finally give an explanation of what is happening in a cask as far as we can tell at the moment. It’s a complicated business, one that most people pay lip service to, but one that is brushed over despite it’s vital importance, especially when you realise that without it we would not have Whisky as it exists today. Hold on to your hats, and jump into casks!
The first topics I’d like to tackle are the different cask sizes, where they come from and the effect of maturation on each, regardless of the previous contents that were seasoning the casks. Scotch Whisky must mature in Oak in Scotland for a minimum of 3 years and a day, and it must be matured in a cask no greater than 700 litres in size to ensure sufficient wood contact.
Cask Sizes in use today:
Gorda 700 litres: A cask used for marrying American whiskies, legally the largest capacity cask we can use for maturation
Madeira Drum 650 litres: Very uncommon in the Scotch Industry but used from time to time, mainly for aceing and finishing.
Sherry Butt 500 litres: A cask traditionally used for maturing and fermenting Sherry
Port Pipe 500 litres: A cask traditionally used for ageing Port, taller and thinner than a Butt
Puncheon 500 litres: A cask constructed from spare staves, shorter and fatter than a butt
Hogshead 250 litres: A cask size introduced to make warehouse mathematics easier
French barrique 225 litres: A cask used for maturing wine
Quarter Cask 80 litres: A small cask recently re-introduced into the industry to age whisky ‘quicker’
Bloodtub 50 litres: A tiny cask rarely used these days used
(All cask sizes are approximate. Remember that these are hand crafted vessels and can vary from cooperage to cooperage. This is why all casks are weighed before and after filling to ensure exact content knowledge)
The first casks used in Scotland would have undoubtedly been small. Bloodtubs and Quarter Casks would have been kept in the cellars of the wealthy and filled with the local Whisky. These casks would be tapped half way up and refilled with new spirit (legally Whisky at the time remember) in a crude solera ageing system. The rich would have been amongst the first to experience the effect of oak on spirit and would have been extremely proud of the unique product ageing in each of their cellars. This was not done on a grand scale though, as people filled only what they could afford and cooperage was expensive.
The first cask sizes used on any great scale, would have been standards in the European wine industry. The first people to have wood policies as such in Scotland would have been the blenders. Distilleries would have been storing Whisky before the first blends in the 1850s, but even these products were stored to be sold at the greengrocers. These are the greengrocers who would eventually go on to become the blenders. A perfect circle and a fact that allows us insight into how the industry at the time was shaping up and exactly where the roots of today’s business were planted. These gentlemen were extremely important, many of them went on to become barons and landowners due to their entrepreneurship and innovation!
|Sherry Butt in construction|
They learned the art of blending from the tea trade, and were in an extremely privileged position when it came to ageing Whisky, as they were also the bottler’s of the time. This meant they imported casks of French wine, ports, Madeiras and Sherries which they blended and bottled themselves. It was only natural then that they sold these empty casks to the whisky industry for storing Whisky that they would then buy back.
So the first casks used on an industrial scale would have been Sherry butts, Port Pipes and French barriques. When the law changed in 1915 outlawing unaged whiskies, the distilleries jumped at the chance of buying second hand casks from the blenders and greengrocers probably without realising the importance or indeed the legacy laid down which still emanates through the Industry today.
French barriques however threw up an unusual problem. One which continued as we went on to source barrels fron the Bourbon Industry in the USA. The warehousemen of the late 19th and early 20th century were not the most literate of workforces and the guagers were rarely sober. To switch between 180 or 195 litre casks and 500 litre casks was not the easiest mathematical task in the world for either profession. Something had to be done.
|French Barriques being disgorged at Bruichladdich|
This was the reason that the industry introduced a Hogshead (a traditional 15th century measurement) into the mix. It simply made the mathematics of the day easier. Coopers would bring in three or four barriques or barrels and build two 250 litre hogsheads to make stock-take easier.
Today the most common size of cask in the Whisky industry is undoubtedly the American Standard Barrel. These can only be used once by law to mature Bourbon and therefore offer an extremely cheap source of oak for our industry.
|American Standard Barrel|
Today distilleries are rarely building hogsheads, (a process making even more sense when casks were shipped in flat pack form) as it is now cheaper to ship casks whole. Factor in that the smaller a cask, the larger the percentage of the Whisky inside is in contact with the wood at any giving time, therefore the quicker the Whisky picks up the characteristics from the oak as well a the introduction of computers into the stock system and it makes perfect sense to use American standard barrels.
The final thing I should point out about casks is their finite lifespan. Casks contain lot of compounds and goodness that we look for in our Whisky (more on the specifics later) however they will lose these benefits as they get older and the Whisky leeches them out.
I like to think of a cask like a teabag. If I made myself a cup of tea and then you used the same teabag for your cup of tea, yours would be lighter in colour and less pungent in taste and aroma unless you left the teabag in longer. Casks work the same. Each fill will remove more from the wood eventually rendering it exhausted. Subsequent fills will require longer and longer periods to gain significant flavours and most refills will never match up to the colour or aroma of a previous incumbent. The life of a cask looks like this:
|A trail of tannins from European Oak stacks|
Virgin oak is filled with Sherry/Bourbon/Wine for 1-8 years. These products remove lots of colour and woody aromas from the cask.
These casks are then filled with Scotch. What we now call a first fill cask. The Scotch removes more aromas and flavours during it’s life in here. Around 12 years.
The cask then becomes a refill where we put another batch of Scotch in. This batch will be lighter and less woody in flavour but can stay in the cask much longer if need be. Up to 40 or 50 years in special cases.
If the wood still has more to give a third fill may take place, but this is less common these days.
The cask can then become a marrying tun for resting blends and marriages of single malts, or if no longer watertight we can make garden furniture or woodchips out of the casks.
Some companies today still use casks up to 6 or 8 times. However, gladly the industry is realising that after 3 fill maximum a cask will have very little left to give and we are seeing more and more Whisky makers refuse to use casks more than three times. These casks will still be in our industry for over 60 years, Oak really is the most important part of our final product and the more us drinkers know about it the better our Whisky Adventures will become.
Next time we will focus on types of oak and their special properties.
In my glass: PC9 a perfect marriage of different wine casked whiskies from Bruichladdich to give a superbly married and well balanced peaty monster.