Malt whisky whisky regulations require malt whisky to be made in pot stills using water and malted barley without the addition of any other cereals, and the whisky must be aged for at least three years in oak casks. The use of new barrels is not required. Caramel coloring can be added, but no other additives are allowed. Irish whiskey regulations are almost identical to Scotch regulations. Malt whiskey must be distilled in a pot still from a mash of 100% malted barley, which may be peated or unpeated in character, although unpeated malt is typically used. All Irish whiskeys must be
Bourbon whiskey oak containers for aging. In practice, these containers are generally barrels made from American white oak. The spirit gains its color and much of its flavor from the caramelized sugars and vanillins in the charred wood. Straight bourbon must be aged at least two years, and blended bourbon must contain at least 51% straight bourbon on a proof gallon basis (i.e., most of the alcohol in the blend must be from straight bourbon). The remainder of the spirits in a blended bourbon may be neutral grain spirits that are not aged at all. If a product is labeled merely as