Distillers say that as much as 70% of the flavor of Straight Bourbon or Rye comes from the maturation process in charred barrels that had not been used before the whiskey is entered. The barrel is a crucial part of this process so it is important to know what is happening in the wood that contributes to the flavor profile of the whiskey. I will give a brief description here of what I have come to understand happens in the barrel.

When a cooper makes a barrel he is creating many different levels of flavor in the wood. In order to bend the wood staves into a tight container that will hold whiskey, the cooper applies heat to the wood. This heat helps make the wood flexible so the staves can be bent and shaped. The heat is not so great that the wood catches fire, but it is hot…