Americans, of course, are renowned for their love of new things, so the fact that their law demands that bourbon must always be matured in new barrels should come as no surprise. Nor will it surprise those familiar with the Scottish reputation of being, shall we say, careful with money, that Scotch whisky barrels are always second-hand.
Traditionally, 500-litre sherry casks called butts have been used. But these, according to David Robertson, the master distiller at Macallan's, on Scotland's famous (to whisky-lovers) river Spey, became scarce during the Spanish civil war of the 1930s. That was when many Scotch distilleries, though not Mr Robertson's, turned their eyes, as a source of alternatives, to Kentucky.
Liquid-gold mine: Frankfort, KentuckyCorbis
Second-hand goods, of course, are always a little worn—and second-hand barrels are no exception, since they have had some of their chemical vim and vigour sucked out of them. According to Lincoln Henderson, Labrot & Graham's master distiller, the new barrels are responsible for roughly 80% of his bourbon's final character and flavour. By contrast Bill Lumsden, Glenmorangie's head of distilleries and maturation, reckons his used bourbon casks are responsible for only 60% of his whisky's flavour and character. This difference is exactly as it should be; most Scottish distillers don't even want new barrels since the flavours from the wood would overpower the character of their distillate.
At the same time, many distillers are coming to see the value of introducing different woods into the maturation process. Some have taken to “finishing” their whisky in different casks for a year or two, to modify the flavour. The Glenlivet 12-year-old, for example, is available in a variant that has been finished in a barrel made from Limousin oak, Quercus robur, from France. Limousin oak, which is used to mature cognac, contains a different spectrum of chemicals from Quercus alba, and this difference is discernible in the taste. St. George Spirits, an American distillery well-versed in eaux de vie, recently produced its first single malt whisky and used a combination of barrels during maturation. Some 82% of the spirit was matured in used bourbon barrels, 12% in new French oak ones, and 6% in former port casks, allowing the mingled compounds from the barrels' wood and from any previous liquid inhabitants each to make their particular contribution to the finished whisky.
Past its best, by now, alasMary Evans
Maturation, too, differs between America and Scotland. Although Scotch can legally be sold once it is three years old, few serious drinkers would touch such a youthful spirit. In Scotland, not mere years but decades add distinction. That is largely to do with the climate. As an experiment, Maker's Mark swapped barrels with a Scottish distiller to see how much the environments of the two places affected the whisky's maturation. The experiment's outcome was that one year in Kentucky, with its hot summers and cold winters, was roughly equivalent to four in Scotland, with its much more consistent and humid climate. But even minor environmental differences can produce marked results. As Buffalo Trace's president, Mark Brown, points out, one of the distillery's distinctive bourbons, Blanton's, comes exclusively from casks matured in the firm's only metal-sided warehouse. The other warehouses are brick buildings with very different thermal characteristics, yielding different-tasting bourbon.
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