Mixed

Whiskies of mixed maturation have been around since the advent of blending, with Scotch and Irish whiskies from as early as the 19th century containing spirit matured in both American and European oak. Today, the majority of blended whiskies will contain a portion of both bourbon and sherry cask matured malts and grains, as well as refill and variety of other casks.

Blending is also an important aspect of single malt bottling, with distillers creating many proprietary products by vatting whiskies they have matured in an array of different casks in order to maintain consistency in their colour and flavour profiles. Another form of mixed maturation comes from the modern process of cask-finishing, technically known as "secondary maturation." This involves transferring the entire contents of a cask or casks into a new one, ordinarily of a different wood type with the most common finish being in oloroso sherry. Despite Balvenie and Glenmorangie distilleries being regarded as the pioneers of the practice, Auchroisk was actually the first, ageing the casks for its The Singleton vintages in bourbon wood for 8 years before a further 2 in sherry.

Cask-finishing is now a staple of the wood policies of distillers and even independent bottlers across the world and despite the strict regulations on cask ageing of bourbon, its primary whiskey category, even American distillers are increasingly experimenting with cask-finishing. Only permitted to be labelled bourbon if the cask finish is specifically stated on the label, the trend was kicked-off in 2006 by Angel's Envy and the launch of its core port-finished release, and since then American distillers have transferred their whiskies from new charred white oak to everything from wine, rum and Scotch whisky casks to ex-maple syrup barrels.