The malt is made from barley, and later combined with a mostly tasteless grain alcohol base. Chivas Regal , for instance, uses over 30 malt whiskeys in their product. U.S. produced whiskey is usually made either from rye, corn or barley. These are often blended. This can cause problems for the kosher consumer.
Canadian whiskey is rye and barley.
It is then aged in used American bourbon barrels. Seagram's V.O. whiskey, one of the most popular, is a blend of over 120 different whiskeys. The cabeza is shredded, and the liquid extracted. This liquid is fermented and then distilled into mescal. Commercial mescal and tequila are generally distilled twice, to 110 proof, then watered back down to 80 proof.