The Phenomenon Known As The Angels Share
As the spirit ages in the barrel, evaporation results from the porosity of the wood. The normal barrels used in distilleries hold about 53 gallons and every year, approximately 10% of the remaining spirit evaporates. It is actually quite normal that a 15 year old single malt Scotch whiskey will be just less than half full at the time of bottling. The loss of the spirit caused by evaporation is known as the Angels Share. When factors such as the humidity and the temperature are considered in the above situation, evaporation can cause the percentage of alcohol to either decrease or increase. The decrease or increase is determined by the amount of water or alcohol that actually evaporates. For example, warehouses that have high humidity cause the percent alcohol to decrease, while those with a lower humidity have an increase in the alcohol content. One way to limit the Angels Share in your Red Head Oak Barrel is to cure the barrel with water so it soaks in to the wood instead of your liquor.