Barrel for at least two years in new, charred oak containers. Other forms of whisky aged in used barrels cannot be called "straight". International laws require any whisky bearing the label "Scotch" to be distilled and matured in Scotland for a minimum of three years and one day in oak casks. By Canadian law, Canadian whiskies must "be aged in small wood for not less than three years", and "small wood" is defined as a wood barrel not exceeding capacity. Since the U.S. law requires the use of new barrels for several popular types of whisky, which is not typically considered
Single malt whisky not always clear what the term "single cask" refers to. At least some producers release vattings of multiple barrels that have been matured together for one final period in a larger single cask as "single cask" whisky. While cask-strength, or undiluted, whisky (sometimes having an alcohol content upwards of 60%) has recently become popular, the vast majority of whisky is diluted to its "bottling strength" - between 40% and 46% ABV - and bottled for sale. Whisky can be "chill filtered": chilled to precipitate out fatty acid esters and then filtered to remove them. Most whiskies are bottled this way,