Sitting on the table in front of me, as I write this, is my most treasured bottle of whisky. It’s a Glenlivet; still largely full, I’m pleased to say. This Speyside is not necessarily my favourite malt, but the contents of the bottle were distilled in the same year that, so to speak, I was: 1956. Now anyone who knows anything about wine will know that 1956 was a year of frosty catastrophe; wines bearing that vintage on their labels are very hard to find, and probably even harder to enjoy. A whisky distilled in 1956, in other words, is one of the few chances I’ll ever get of an anniversarial tipple, which was why I made the extravagant purchase. So, hey, what’s it like?It’s dismal. Heavy in colour and rather lifeless, it smells of wooden casks and little else. In the mouth it tastes like a spirity oak macerate, with an aftertaste of liquorice and aniseed. It’s flat; it’s tired; it’s old. I don’t want to sound cocky, but I’m actually in better shape than the whisky is. (It’s a Gordon & MacPhail bottling, by the way, though crucially it doesn’t say when the whisky was taken out of wood.)It was this bottle which taught me a lesson I’ve had reinforced many times subsequently: that single cask or small-run bottlings are hugely variable. Some are very fine; some are tedium itself. Assuming the stillmen were doing their job properly, all of a particular distillery’s whisky
begins life as an identical [new make’. So what creates these differences?Casks and time. Of the two, time is a constant; casks aren’t. Perhaps the most astonishing and least widely understood detail of Scotch whisky production is that every single drop is aged in a raggle-taggle collection of second-hand wooden casks. Anything second-hand, of course, is inherently variable, and casks are no exception. I remember standing in the Robertson & Baxter blending room with John Ramsay several years ago looking at potential components in a trial blend the company was indulgent enough to let me assemble. ‘Take a look at this,’ said John, handing me a nosing glass. I sniffed. Youngish, I guessed: 18 months in wood? In fact it had been there seven years. The cask was doing nothing for it; the cask had no more to give.Four main types of cask are used for ageing Scotch. Sherry butts of 500 litres are perhaps the most famous, though they represent a very small proportion of the total cask pool of the industry. They are famous because of the fruity sweetness they impart to whisky, and because of the skill with which they have been used as a marketing tool by various malt brands, most notably The Macallan. Sherry butts are in principle made from brown, European oak, Quercus sessiliflora or Quercus petraea, though American oak interlopers have been found.The second type of cask is the bourbon hogshead cask of 250 litres or American spirit barrel of 200 litres, used much more widely than sherry butts. They are made of white, American oak Quercus alba, and give Scotch whisky a more delicate dose of the violet-vanilla perfumes which steamroller out of most bourbon itself.When first used for Scotch, the two types of cask above are called [new’, even though they have previously contained sherry or bourbon. The overwhelming majority of Scotch, however, is aged in refill casks – casks of either type which are on to their second, third or fourth filling of whisky. At each stage, more of the cask character is lost; gradually the wooden vessel moves towards neutrality, giving the spirit inside no more than a gentle oxidation. I’m not dismissing refill casks, though. Quite the contrary, as we’ll see later.The fourth type of cask is a relatively new development, but one which is having a major impact on Scotch whisky ageing regimes: rejuvenated casks. These are casks which have had their previous inner char coat scraped off, and the fresh wooden surface beneath newly charred. The effect is quite unlike any of the three categories above; it replicates a brand new cask, something quite untraditional for Scotch. Ageing characteristics (colour acquisition and the extraction of sweet wood notes) are relatively rapid in a rejuvenated cask, making them very interesting to company accountants. Casks can be rejuvenated several times.Anyone who has sampled new-make malt whisky, fresh from the still, will concede that it’s a very odd drink, and quite unlike the finished product. United Distillers and Vintners (UDV) categorises its many new-make malts under 16 different style headings: clean, fruity, green/grassy, green/oily, meaty, metallic, musty, nutty, peaty, perfumed, sour, spicy, sulphury, sweet, vegetable and waxy. (New-make spirit often smells soapy to me.) What actually happens to it as it ages in the cask?‘Casks take out the baddies and put in the goodies,’ is how Maureen Robinson, quality controller for UDV, puts it. In other words, elements of the new make which are sensorially undesirable (like sulphur notes or aldehydes) are lost; while the whisky absorbs positive aroma and flavour contributions from the wood itself by a process Robinson calls [in-drink’. These include colour compounds, vanillins, lactones and sugars. The third process which occurs during ageing is an interactive one by which elements in the spirit combine with other elements to an improving end (tannins, for example, become acetals, and alcohols and acids become acetates).According to Robinson, spirit ages more actively at the beginning of the cycle, during the first six or nine months of lying in the cask, than it does during subsequent years: elements are extracted from the wood, oxidation processes begin, and the water which has been added to reduce the spirit from its neat, still strength provokes hydrolysis reactions. ‘It does slow down later,’ she says, ‘but it never stops. Indeed the longer you leave the spirit in the cask, the more the influence of the cask comes to the fore and the less important the interactive processes are.’ This might explain the disappointment of my Glenlivet: too much cask, not enough whisky. After a while, even the goodies become baddies.There is, in other words, most definitely an optimum ageing period, and to over-age a whisky is as damaging as to under-age it. ‘Beyond a certain point, age is heaviness,’ points out UDV’s Master Blender Ian Grieve. Grain whisky, Maureen Robinson adds, needs less ageing than malt whisky does, and malt whiskies themselves need different ageing regimes depending on their fundamental new-make character (the Six Classic Malts, for example, vary between 10 and 16 years old). She claims, by contrast, that there are no substantial differences in general [ageability’ of malts from different regions of Scotland, nor does she feel that precise location within Scotland matters much to the way a cask ages. Many malts are matured at locations other than where they were made. (By way of contrast, check out Jameson’s views on ageing in Northern Ireland compared to the South in this issue.)UDV husbands some seven million casks of whisky, and one of the biggest headaches it faces is trying to predict future demand. For financial reasons, no whisky producer ever wants to age a cask of whisky for a week longer than is strictly necessary – yet the very fact that Bell’s was reformulated from a five-year-old to an eight-year-old shows how crucial age is to overall quality. ‘We did make one or two additions, like Linkwood, to the malt components, just to round it out a little, but at the same time we didn’t want to lose the fundamental biscuity, cake-mix character which Bell’s always had,’ says Maureen Robinson. ‘So the only major way to bring the quality up was to put in more goodies, more mature qualities, more age.’ Master Blender Ian Grieve claims the Bells’s changes were ‘75 per cent due to ageing and 25 per cent due to a change of recipe. The age itself brought Bell’s a great deal more character.’ To summarise, then: Scotch whisky as we know it, both blended and malt, tastes as it does because the baby new-make spirit has received a long, formative upbringing in a cask. There is, though, no formula for ideal ageing. In Ian Grieve’s words, ‘age is not an absolute. Relative maturity is the key.’ Statistically speaking, most whisky seems to be at its best between eight and 16 years old, and because of the inherent variability of casks, a modicum of blending seems to me to produce a better spirit than does the unblended, single cask (though many readers, doubtless, will disagree).The question of which wood should be used for ageing whisky is a difficult one, but on the basis of a short tasting I did with Maureen Robinson, as well as a large tasting I attended of the 100 component malts in Seagram’s vatted Century in summer 1998, my vote would certainly go to refill casks rather than [new’ sherry or bourbon casks, or rejuvenated casks. ‘All the master blenders,’ points out Ian Grieve by way of example, ‘say that Macallan is a much more interesting dram when it isn’t in a sherry cask.’ The second fill seems to be just about perfect for letting the intrinsic quality of the spirit express itself over a ten or 15-year span, shaped but not dominated by wood. It’s there that you find the purest, most expressive and most allusive Scotch, even if the marketeers don’t like it.