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
American whiskey it is aged, it must be aged in used or uncharred oak barrels "at not more than 62.5% alcohol by volume (125 proof)". In practice, if corn whiskey is aged, it is usually aged in used bourbon barrels. Straight whiskey is whiskey that was distilled to not more than 80% alcohol by volume (160 proof) that has been aged for at least two years at a starting alcohol concentration of not more than 62.5%. It has not been blended with any other spirits, colorings, or additives. A straight whiskey that also meets one of the other above definitions is referred