What, EXACTLY, is the “Angels’ Share”?
While it differs from barrel to barrel, the “Angels’ Share” is the slow evaporation of distilled spirits aging inside of each one. This “libation” gets its name because it’s an “offering up to the angels in heaven to pray for a really great bourbon in the barrel”. After all, there’s no holier well for a liquid offering!
Did you know that a barrel breathes? Wood is actually very porous and with the change of seasons, it expands and contracts. That charred, dry thirsty wood absorbs as much as 5% upon initial filling and each year thereafter, a smaller proportion (up to 2%) runs through the wood grain. So, it isn’t uncommon for a 15-year-old cask to be half full by the time it is bottled.
There are 3 main factors that affect the Angels’ Share:
- Barrel Cooperage – how tight the cask staves are and the wood variance. For example, oak is a natural substance that varies so even if the casks were made at the same time, by the same source of materials and the same cooper, there will be some differences in casks. The size of a cask also makes a difference, as smaller casks actually evaporate more because there’s more wood-to-liquid contact.
- Ambient Temperature – whether the climate is mild, warm, dry, wet, etc. For example, 1 year of aging in our hot and humid Southern climate may equal 3 years in Ireland or Scotland’s wet climate for the exact barrel of liquid.
- Air Flow – the circulation of air around the barrels in the rackhouse affects the proof of a barrel. The locations of the barrels in storage also matters. For example, the atmosphere at the top of the rackhouse is more hot and dry, while the bottom is more cool and moist.
So… how much is lost each year due to evaporation, you ask? Honestly, there is no 100% correct single answer to that question. There are many variables, including the entry proof of the spirits into the barrel. For example, spirits barreled at 125 proof have a higher alcohol versus water ratio than spirits barreled at 100 proof. High humidity results in more alcohol evaporating than water, while low humidity (with higher temperatures) draws more water through the staves – which means a higher alcohol content!
The truth is, even the angels in heaven can’t give an exact percentage of their share versus your share until the bung is pulled from the barrel. One thing is for certain though… while the angels get their fair share of aging spirits, the devil also gets his cut once that barrel is dumped (which is the amount of alcohol that’s been lost to barrel absorption)!