The Daily Beast:
One of the most fiercely debated new developments is the question of how the wood is “seasoned” before being made into barrels. Seasoning takes into account the time between when the tree is cut down, inspected, rough-milled into staves and then made into barrels. While it sounds straightforward, the wood needs to be dried between milling and becoming a barrel—anywhere from four to about 48 months of air drying, and/or kiln drying.
With proper seasoning, along with the toasting and charring that creates sweeter flavors, oak becomes a major partner in the creation of whiskey flavor. That’s why seasoning has become a selling point for the higher end of the barrel and bourbon market.
Until I moved to Tennessee, I had no idea how important the physical barrel was to various whiskeys and bourbons.