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
Irish whiskey John Powers and George Roe (all family run, and collectively known as the "Big Four") came to dominate the Irish distilling landscape. The chief output of these distilleries, known as single or "pure pot still" whiskey, was made from a mix of malted and unmalted barley, and solely distilled in pot stills. The style, having initially emerged as a means of avoiding a 1785 tax on malt, endured although the tax had been later repealed. In fact, even by the late 1880s, only two of Ireland's then 28 existing distilleries were producing single malt whiskey, the rest steadfast in their