The Angel’s Share and the Devil’s Cut
3-4% of bourbon naturally evaporates during each year of barrel aging, resulting in a net loss of roughly a third of the amount over 7-9 years. They call this portion the Angels’ Share, having escaped up to heaven to quench the thirst of the divine drinkers above.
Bourbon also remains trapped inside the wood of the barrel after it has been emptied. Called the Devil’s Cut. Jim Beam made the phrase popular when it extracted the bourbon, blended it with extra-aged stuff, and bottled it at 90 proof “for robust, premium bourbon with deep color, aroma and character.”