Single malt whisky (and sometimes a third) time. The final spirit, called "new make spirit", generally has an alcohol content of 60 to 70%. Most new-make malt whisky is diluted to about 62.5% a.b.v. before it is placed in casks to mature. The "new-make spirit", or unaged whisky, is then placed in oak casks to mature. By law, all Scotch whisky must be aged for a minimum of three years in oak casks, though many single malts are matured for much longer. The whisky continues to develop and change as it spends time in the wood, and maturation periods of twenty years or
Scotch whisky or "non-chill-filtered" has not been through a filtration process during bottling that removes compounds that some consumers see as desirable. Whisky is aged in various types of casks—and often in used sherry or port casks—during distinct portions of the maturation process, and will take on characteristics, flavour and aromas from such casks. Special casks are sometimes used at the end of the maturation process, and such whiskies may be labelled as "wood finished", "sherry/port finished", and so on. There are two basic types of Scotch whisky, from which all blends are made: Excluded from the definition of "single grain Scotch