As a sommelier and brewer, I have had the privilege of working closely with whisky and understanding the fascinating process of aging in casks. One of the intriguing aspects of this maturation is the phenomenon known as the “angels' share.” This refers to the portion of whisky that evaporates from the cask over time.
At the initial stages of aging, the angels' share is at its peak, typically around 3.5% to 4% per year. This means that for every year the whisky spends in the cask, a significant amount, approximately 3.5% to 4% of the liquid, is lost to evaporation. This evaporation occurs through the porous wood of the cask, allowing the whisky to interact with the surrounding environment.
To put it into perspective, imagine filling a cask with freshly distilled whisky. Over the course of a year, about 3.5% to 4% of that whisky will evaporate into the air, escaping the cask and leaving behind a smaller volume of liquid. This evaporation is often referred to as the angels' share, as it is believed to be enjoyed by the angels in whisky folklore.
However, it is important to note that as the whisky ages, the rate of evaporation decreases. This means that while the angels' share continues to exist throughout the entire aging process, the percentage lost each year becomes smaller. This is due to a variety of factors, including the saturation of the wood and the formation of a protective layer known as the “angel's crust” or “whisky fungus,” which helps to reduce further evaporation.
It is worth mentioning that the amount of angels' share can vary depending on various factors, including the type of cask used, the climate of the aging warehouse, and the specific distillery practices. For example, whiskies aged in hotter climates may experience higher evaporation rates compared to those aged in cooler regions.
In my own experiences with whisky production, I have witnessed the impact of the angels' share firsthand. It is truly remarkable to see how the whisky evolves and transforms over time, as the angels claim their portion. The loss of liquid to evaporation contributes to the concentration and development of flavors and aromas in the remaining whisky, making each sip a unique and cherished experience.
The angels' share of bourbon, or any whisky for that matter, can be estimated to be around 3.5% to 4% per year during the early stages of aging. However, this percentage gradually decreases as the whisky matures. The angels' share is an integral part of the aging process, adding to the complexity and character of the whisky that we enjoy today.