​During the maturation process a cask will go through notable changes. The clear liquor will slowly absorb the colours from the oak cask it is stored in, overtime completely changing its appearance. The “angels” will begin to take their share. Around 2% of the spirit will be lost to evaporation each year. Put simply, the older a cask is, the less whisky there is to be bottled. This explains why older bottled whiskies are significantly more expensive.​