Bourbon 101: The Mechanics of Barrel-Aging

By law, bourbon must be aged in a new charred oak container-but there are variables and considerations that affect the final flavor outcome. These are the mechanics of barrel-aging: how it works, why it matters, and what terms like “angels’ share,” “toast,” and “char” mean.

[@44Mat]

Climate Friendly Eco Friendly Barrels....The darkening process is magical

[@Pinoynoir7]

Are all bourbon barrels made from the same type of oak?

[@txmike1945]

Most, not all, are of American White Oak, but there is considerable variation depending on where the oak grew and what part of the tree the wood comes from. And of course the type of charring. Then beyond barrel prep there is the influence of location in the storage unit during the years of aging. You might be interested in what one company, Buffalo Trace, has done to explore this in depth:
thewhiskeywash.com/whiskey-styles/bourbon/buffalo-trace-aims-to-explore-all-things-oak-in-new-bourbon-series/