The Angel's Share

Bourbon barrels are made of oak, and oak is porous. Every year a barrel spends aging in a rickhouse, a percentage of the liquid inside evaporates straight through the wood. Distillers call this loss the Angel’s Share — the portion, as the old saying goes, that the angels take for themselves.

In Kentucky’s climate, a barrel typically loses 2–4% of its volume per year to evaporation. Over a 10-year aging period, that can mean a barrel loses close to a third of what it started with. Hotter, higher floors of a warehouse — the rickhouse, in distillery language — lose more, faster; cooler lower floors lose less, and airflow and construction (traditional wood-frame rickhouses behave differently than modern metal-clad ones) add another layer on top of floor alone. That’s why warehouse position, not just the calendar, shows up so often in tasting notes and allocated releases.

A barrel from a hot top floor at year nine might taste more like a “12-year” than an actual 12-year barrel from a cool bottom floor — which is exactly why two bourbons with the same age statement can taste meaningfully different, and why warehouse position is its own flavor variable, distinct from age itself.