American whiskey labeled as one of these types, the whiskey must be distilled to no more than 80% alcohol by volume (160 U.S. proof) to ensure the flavor of the original mash is adequately retained, and the addition of coloring, caramel, or other flavoring additives is prohibited. All of these, except corn whiskey, must be aged at least briefly (although no minimum aging period is specified) in charred new oak containers. These restrictions do not exist for some similarly named products in some other countries, such as Canada. American corn whiskey does not have to be aged at all – but, if
Canadian whisky more rye is required if it were added to a mash bill alongside the more readily distilled corn. The base whiskies are distilled to 180 to 190 proof which results in few congener by-products (such as fusel alcohol, aldehydes, esters, etc.) and creates a lighter taste. By comparison, an American whisky distilled any higher than 160 proof is labelled as "light whiskey". The flavouring whiskies are distilled to a lower proof so that they retain more of the grain's flavour. The relative lightness created by the use of base whiskies makes Canadian whisky useful for mixing into cocktails and highballs.