Every single batch of whisky is affected by a phenomenon with a curious moniker— the angel’s share. This is the volume of liquid lost to evaporation during the production process, which is about two percent per year. Indeed, the term conjures up scenes of raucous merrymaking in the heavens. However, to truly determine whether this benefits or hurts the end product, it is worth understanding some basics of the whisky-making process.
The wood of the barrels that whiskies are generally aged in, absorb much of the unwanted components of the distillate while suffusing it with complex characteristics and flavours. However, the porosity of the wood results in unavoidable evaporation of some of the liquor. On the plus side, this actually enhances the whisky, concentrating it, speeding up maturation, and making it smoother in body. In fact, it often turns low-quality moonshine into a sophisticated brew with a silky clean finish.
On the other hand, because many whiskies are left to mature for several years, the total volume of liquid lost to evaporation can add up to a significant amount, resulting in a colossal level of loss. For instance, a fifteen year old scotch may lose a whopping 30 percent of its volume by the time it has fully matured. In hotter, more arid climates, this figure can even double, resulting in more than four or five percent a year in angel’s share. For example, a bourbon brewed in Kentucky will lose a lot more as angel’s share than a scotch distilled in Scotland’s chilly highlands.
Conclusively, the angel’s share phenomenon is both a blessing and a curse.