Straight whiskey must be aged for a minimum of two years in new charred oak casts. If aged for less than four years, the whiskey must show its age on the label (steer clear of 2-3 year old whiskies). No colouring or flavouring is permitted to be added to straight whiskey. If the corn content exceeds 80% then it becomes Corn Whiskey, although this is then matured in aged, uncharred barrels.