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 more are not uncommon. During the time it spends in the wood, a significant percentage of each cask's content will evaporate. The lost product is known as the angel's share. The selection of casks can affect the character of the final whisky. Outside of the United States, the most common practice is to reuse casks that previously contained American whiskey, as US law requires several types of distilled spirits to be aged in new oak casks. To ensure continuity of supply of used oak casks some Scottish distilling groups own oak forests in the US and rent the new barrels