Whisky Words: Angels’ Share
The Angels' Share refers to the amount of ethanol and water that is lost due to evaporation during ageing.
During maturation, a proportion of spirit is lost through evaporation. Ethanol, water and some other congeners turn into gases inside the cask and gaseous exchange can be lost to the atmosphere.
In damp Scottish warehouses, liquid is broadly retained and strength is lost. Hot summers in the likes of Kentucky, for example, create a fierce maturation process which leads to Bourbon gaining strength though losing liquid content.
Maturing whisky in Scottish warehouses evaporates to the extent of 1-2% per year, dependent on warehouse style and distillery location. Temperatures at Highland coastal locations, compared to those in upper Speyside, for example, can vary by up to 10°C either way.
Thus, the quantity, rate of loss and maturation benefits are dependent on warehouse temperature, humidity, location and, of course, time. Over a 10 year period, a cask could have lost anything from 10-20% of its liquid to the Angels' Share.
