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Whisky casks are made of oak, from the genus Quercus. The species Q. cerris, (French oak), Q. falcata (Spanish oak), or Q.alba (American white oak), are used. Oak is a natural substance and
therefore variations in density, quality and porosity are inherent. To further complicate and confuse the issue, the wood is split by hand and the casks are constructed by hand. Thus each cask is unique in that it is
larger or smaller than its neighbours, its staves vary in thickness, and no two pores are of the same size. Its influence on the maturing spirit which it holds is therefore going to be different from that of any of its
neighbours.
That is why the recipe for each blended whisky is different. A blender cannot state categorically that the blend for his "Hamish's Choice" Blended Whisky is, for example:
23 casks of Glenardle, 10-year-old
2 casks of Harport, 18-year-old
15 casks of Royal Lochmaben, 7-year-old
13 casks of Leith grain, 5 year-old etc.
because the proportions of each constituent whisky will vary with each blend. When you enjoy a bottle from a single cask bottling, you are
drinking a very finite resource, you are consuming our heritage.
A hogshead will yield roughly 300 bottles (bottled at 40% abv strength) after 10 to 12 years, a butt 500, a barrel 200. The variations in the oak
cask mean that the distiller cannot deliberately exactly repeat this magic of creation. Generally the whisky drunk pre-1900 was young, only the landed gentry being able to afford to mature their spirit. The ageing
cask could be new or previously have held wine, or rum, or butter, or herring, or anything which a cask could hold. Until the 1850s, whisky was sold by the distiller in cask and the publican or whisky merchant bottled
it as required. From 1916, the government insisted whisky be aged in cask for a minimum of three years. The industry was then obliged to find supplies of casks in which to age their product. At this time, all Sherry
imported into the United Kingdom was shipped in cask, to be bottled in the UK by the British merchants. Once emptied, the asks were surplus to the importers' requirements.
Ever keen to save a few pennies, the
canny Scots were thus able to pick them up very cheaply. Likewise, because of the strength of the coopers' union in the USA at the time the laws governing Bourbon production were being created by Congress; it was
written into American law that a Bourbon barrel could only be used once. When empty, they were worth only their value as firewood. Once again the thrifty Scots stepped in and established another economic source of cask.
The situation has now changed in that, since 1983, the Spanish government has decreed that all Sherry must be bottled in Jerez and Sherry butts are
now reusable by the Jerezanos. New Sherry case are now a
considerable cost to the whisky distiller.
With casks being used as many as four or five times over, the most usual type of cask used for filling Scotch and Irish whisky is what is known as a Refill cask. The
casks are carefully checked by coopers between each fill to ensure that there will be no leakage of precious spirit. First fill Sherry casks are nowadays very rarely used to fill new grain whisky, second, third and
fourth refill casks being the usual choice for such whiskies.
One element which has developed in importance in the past 20-25 years is the distiller's awareness of the origins of the cask. So much so that some
now have them made to order by Spanish or French coopers and loan them to a Sherry bodega. Glenmorangie, for example, preferring Bourbon casks, has even gone to the length of buying an oak forest in the Ozark mountains
in Missouri to ensure continuity of supply of a particular quality of oak. The cask has moved a very long way from being a vehicle for transporting whisky or a container of a handy size for sale, and companies are now
experimenting with whiskies aged in oak casks that have previously held Port, Brandy and Rum. Sometimes whiskies are filled in one type of cask, e.g. Bourbon, and then "finished" for their last few months or
so of maturation in another, e.g. Sherry. |
