Maturation
Once distilled the “new make spirit” is placed into oak casks for the maturation process. Historically, casks previously used for sherry were used (as barrels are expensive, and there was a ready market for used sherry butts). Nowadays the casks used are typically sherry or bourbon casks. Sometimes other varieties such as port, Cognac, Madeira, calvados, beer, and Bordeaux wine are used. Bourbon production is a nearly inexhaustible generator of used barrels, due to a regulation requiring the use of new, oak barrels.[8]
The ageing process results in evaporation, so each year in the cask causes a loss of volume as well as a reduction in alcohol. The 0.5–2.0% lost each year is known as the angel’s share. Many whiskies along the west coast and on the Hebrides are stored in open storehouses on the coast, allowing the salty sea air to pass on its flavour to the spirit. It is a little-known fact, however, that most so-called “coastal” whiskies are matured in large central warehouses in the Scottish interior far from any influence of the sea.[citation needed] The distillate must age for at least three years in Scotland to be called Scotch whisky, although most single malts are offered at a minimum of eight years of age. Some believe that older whiskies are inherently better, but others find that the age for optimum flavour development changes drastically from distillery to distillery, or even from cask to cask. Older whiskies are inherently scarcer, however, so they usually command significantly higher prices.
