[1] A blend could be composed of as many as 20 or more different whiskies with different flavour profiles and ages, which makes maintaining product consistency over time a challenging accomplishment for a master blender.
It is sometimes necessary to replace whiskies that go into a blend, and the master blender is responsible for accomplishing this feat without altering the characteristics of the final product.
Experience and a good "nose" are the two most important characteristics for a master blender, although some may also have a supporting academic background in chemistry, microbiology, or other related type of science.
[6][4][7] Nosing spirits involves using the sense of smell to identify specific characteristics, such as different aromas and flavours, that work together to create the desired final product.
For example, according to Max Warner, Global Brand Ambassador for Chivas Regal:[8] "You will need to have a qualification from the Institute of Brewing and Distilling to be considered for a position within the Blending Team.