The Scotch

Chapter 11


To catch Dame Fortune's golden smile,
Assiduous wait upon her
Epistle to a Young Friend
Robert Burns


The final quarter which completes the shield of Ballantine's coat of arms depicts a cask, signifying the importance of maturation in the whisky-making process. During the long years spent slumbering in wood, whisky acquires its colour, mellowness and depth of flavour, a vital 'growing up' of the young spirit which cannot be hurried.

How the art of maturation came about is now the stuff of legend. Back in whisky's bad old days, the distiller it was said kept one eye on his bubbling copper pot and the other out for the exciseman. One smuggler, so the story goes, saw the gaugers approaching and hid his illicit barrels away - either in the ground or among the rocks. The attentions of the excisemen forced him to give up distilling. Some years later, he retrieved his casks and, to his delight, found the whisky smoother and gentler for the keeping.

According to legend, at least, this is how the art and science of maturation began. When young whisky is put into casks, the manufacturing process may be over, but the real shaping of the spirit's character is only just beginning.

During maturation, something not yet fully understood by science takes place within a cask. We know that oak acts as a filter, absorbing impurities from the whisky and allowing wood sugars and tannins to pass into the whisky in return. However, this two-way process adds not only aroma, colour and character, but a further mysterious dimension that no one completely understands. It arises from the curious claim that whisky tends to taste its best only when matured at the distillery where it was made.

Fact or folklore? The answer is probably a question of style rather than science. A glass of whisky taken at a distillery and diluted with the water used to make it, for instance, has an ambience difficult to analyse in the laboratory.

Distillers who have made informal experiments claim that if you move a cask, say, from the Highlands down to an urban warehouse in Glasgow, the change is noticeable.

'It can taste completely different,' confirms ADL's Laboratory Services Manager Denis Nicol, author of several papers on aspects of distilling. 'Because when whisky is matured at the distillery, the micro-climate there impinges on the maturation. Take the whisky away and it matures in a different climate with correspondingly different results.'

The important factor is perhaps not the geographical distance between distillery and warehouse, but the individual micro-climate of the warehouse itself and its suitability for maturation. Dumbuck, for example, where millions of gallons of Ballantine's whisky are matured, has carefully monitored temperatures and an atmosphere amenable to maturing premium quality spirit.

In the long march of whisky-making, maturing spirit in oak barrels is a comparatively new practice. Early blenders such as George Ballantine knew that maturing whisky in casks that had contained sherry, port or sweet wines rounded its character nicely. But up to the late 19th century, most whisky was simply not matured and its youthful taste was disguised with other flavours. The ordinary consumer bought his whisky new, sometimes straight from the still. Some was sold bottled, but in rural areas it was common for customers to take their own jug or small cask along to be filled.

It became common knowledge that whisky improved from maturing in wood and, by 1915, all Scotch whisky had to be matured for at least three years. What no one fully understood at the time was the highly complex chemical process taking place inside the cask. Even now, scientists admit that aspects of maturation remain a mystery.

Researchers have identified between six and eight hundred different components in whisky, but remain unsure how they relate to flavour. They estimate it may take them another ten years to make any headway. A pleasant research prospect, by any standards.

The curious 'growing-up' period of a young whisky, in which it acquires a full, rounded character, depends heavily on the distillery atmosphere and the nature of the wood. Individuality comes from higher alcohols turning into esters and other flavour compounds to give a smooth, distinctive identity.

A Master Blender wisely judges a whisky by maturity, rather than by age. Some spirits reach their optimum state quite young; others may take 15 years, or even longer, to attain perfection.

'As a chemist, I like to think of maturation as the ethanolysis of lignin - the breakdown of wood by alcohol,' Denis Nicol says. 'Because the inside of the barrel has been charred before use, the charcoal acts as a filter, a permeable membrane.'

Legend has it that the American practice of charring the inside of bourbon barrels stemmed from a distiller who bought some that had contained herrings and he had to fire them to remove the smell.

'The products of distillation go into the wood and the harsh flavours - the "green" flavours, as some of them are known - are rounded off,' Denis says. 'During maturation, we lose alcohol through the wood at the rate of about one or two per cent a year. As it goes, it carries with it all the "nasties", which are absorbed into the cask.'

Maturation is a two-way process. A sophisticated inhalation and exhalation as damp Highland or Island air flows through the warehouse. Unwanted impurities which would impair the flavour are drawn out through the charcoal, while the wood of the cask begins to break down chemically, releasing compounds back into the whisky.

'These are things with magic names like vanillin, coniferylaldehyde and sinapylaldehyde,' Denis Nicol explains. 'They are basically aromatic compounds, sugars and tannins derived from the lignin.'

Whisky derives its golden colour, as well as its depth of flavour, from maturation, so the type of container used to store it is vitally important. Casks come in a variety of sizes, diminishing in capacity from butts (500 litres) to puncheons (450 litres), hogsheads (250 litres) and American barrels (173 litres) down to obsolete small sizes used a century ago, such as quarters (127 litres) and octaves (45 litres).

'Whatever the capacity, there has never been a substitute for wood,' Denis says. 'And it has to be oak - nothing else will do. Oak is non-toxic, so you don't find nasties in its cells, and the grain is tight enough to hold the spirit so it doesn't evaporate too quickly.'

The Cooper

The ancient business of making casks without the use of iron nails, which can discolour whisky, requires long training. The cooper's craft combines the skill of a blacksmith and the fine eye of a woodworker to create the perfect container for young whisky to mature. Shaping 26 wooden staves and binding them tightly with iron hoops without the use of glue, nails or screws is a centuries-old craft with its own rules and traditions.

Ballantine's Cask Supervisor Danny Wood learned his trade as an apprentice for six years before becoming a journeyman cooper and rising to foreman. Like all apprentices, he began with the lighter work of fashioning barrel ends. As his familiarity with the specialised tools grew - along with his muscles - his skill was applied to more complicated aspects of cask-making.

The day an apprentice completed his indentures was regarded as a milestone, and Danny's initiation ceremony was no exception. 'You are put in a barrel and everyone pours water over you,' he recalls.

'Then, they cover you in wood shavings, eggs, flour - anything to hand - and roll you up and down the coopers' shop floor. You emerge looking terrible, with your apprenticeship behind you and a career ahead, and celebrate by offering your work-mates a whisky.'

The whisky used in the blending of Ballantine's 17 Years Old has been matured in sherry casks, which contribute sweetness and colour, and American bourbon casks of white oak. Under US law, the latter are used only once for bourbon maturation, but Scotch whisky distillers know that, like sherry casks, oak used for maturing bourbon imparts subtle characteristics to the finished whisky.

The one-time rule was introduced after labour unions put pressure on government to ensure steady work for coopers. Congress agreed and introduced the idea of one-trip casks. A plentiful supply of good, barely-used casks came as music to the ears of the Scotch whisky industry and distilleries snapped them up.


Several things govern the maturation period for both malt and grain whisky - the size of casks, the strength at which the spirit is stored and the temperature and humidity of the warehouse.

Not every drop of Ballantine's 17 Years Old goes to connoisseurs of fine whisky. Because casks are porous, allowing an inward passage of air and a minute migration of spirit outward over years of maturation, about two per cent of the whisky evaporates per year, lost forever - a portion known as 'the angels' share'. Over the years, this tends to accumulate into a considerable amount. Someone estimated that Scotland loses 90 million litres every year - the equivalent of around 150 million bottles floating in the ether - all from natural evaporation through casks.

As casks 'breathe', assisted by the expansion and contraction of the whisky, subtle flavours are drawn from the oak along with a hint of sea air or Highland mist from around the distillery. Some distilleries like to leave their maturation warehouses open to the elements to ensure a good air flow; others prefer to keep temperatures as stable as possible. In this blend of high science and natural influences the size and shape of the warehouse is also deemed to be important.

Crucial temperature variations can take place in a warehouse where casks are stacked 12-high, compared with storage in a single-storey building. Ballantine's maturation houses tend to maintain an even temperature without any volatile fluctuations, so that casks mature as evenly as possible.

'In a warehouse where casks are stacked 12-high you can get what we call "altitude",' Denis Nicol explains. 'There will be subtle differences between spirit matured at the top of the warehouse compared with that matured at the bottom. Some warehouses give a more mellow, rounded flavour than others. The best are those built for traditional three layers of casks, but they are not always economic in today's terms.'

Many of Ballantine's malt distilleries use traditional maturation methods. A favoured style of stacking is known as 'dunnage' - storing a row of barrels side by side, laying wooden rails on top, followed by another row.

Balblair, one of the most delightful traditional distilleries in the industry, is a good example. 'We have no steel racking at all,' manager Jim Yates explains, 'and the only concrete in evidence is a path down the middle to run the stacking machine on. We rely on the old dunnage method with casks built up on wooden rails. All our warehouses are low with a good circulation of air. The warehouses that have been here since 1895 have casks about three high, and I believe you can tell the difference.'

One of the problems with low warehouses is that they occupy a lot of space, but experts consider the results to be worth it.

'The maturation house we built in 1964 was 500 feet long, the longest warehouse of any distillery in Scotland,' Jim Yates says. 'Eventually, the insurance company became a little nervous about the size - if there had been a fire, we would have lost most of our whisky - so we had to build a wall across the middle and turn it into two.'

The Highland air flowing through Balblair's warehouses is heavy with moisture from the Dronach Firth, on Scotland's North Sea coast, just a kilometre away. On Islay, both Ardbeg and Laphroaig's maturation houses overlook the sea.

Distillery managers have found that whisky exposed to sea air takes slightly longer to mature, possibly because wood expands and contracts more slowly in the even temperatures of the Gulf Stream around the western islands. In addition, a butt of whisky takes longer to mature than a hogshead and a 'hoggy', in turn, longer than a barrel.

But making whisky never was a hurried business. Quality is the main concern of the Master Blender.

'Maturity is a very subjective area,' Denis Nicol explains. 'What to one person may be nothing more than a half-whisky might be considered just right to someone else. It's a subject best left to the expertise of the blender. However, I suspect that each individual whisky has its own optimum maturation time. I would say a Speyside might be 12 years, while an Islay malt might be 15 or 17 years.

'A Laphroaig ten years old, to offer an example, has a heavy peaty presence with quite a smoky flavour. When you mature it another five years, the peat becomes suppressed and the woods begin to come out. I won't say you get a better balance of wood and peat reek, but you notice an almost cognac note to the spirit and the wood carries lingering flavour notes which begin to come through.'

Once bottled and sealed from the air, all maturation stops, which is why every bottle of Ballantine's 17 Years Old has consistency of quality and flavour.

The malts in 17 Years Old are distilled at around 70 per cent alcohol by volume and reduced to 63.5 per cent or 111 proof before being put into casks.

'Some places in the industry put it into the cask at strength natural, straight from the still,' Denis says. 'No water is added and it means you don't have as much to mature. However, I believe that adding water actually promotes maturation and enhances the process.'

Because of the high strength of matured whisky used for blending, it is reduced with neutral, demineralised water to 43 per cent alcohol by volume.

'Demineralised water removes metal ions, like calcium, magnesium, iron or copper which can react with the whisky. Contact with iron, for example, can turn it permanently green or black. Calcium causes "flock", a technical term for minute particles which create haze,' Denis adds.

When the mature whisky is ready for bottling, the four elements which make up Ballantine's crest have played their part. The living barley has combined with pure mountain water in malting, mashing and fermentation. The individuality of the pot still has played its part and, finally, the young spirit has interacted with oak to mellow into fine, rounded whisky.

At each step of the production process every effort has been made to capture the natural harvest of ingredients at their prime, from the full flavour of fine barley, hand-cut peat and pure water, to distilling and maturation which combine the best of tradition and modern technology.
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original copyright (c) Allied Distillers Limited, 1996