Most age expressions from distilleries are a vatting of casks, the youngest of which is the designated age expression. So Ardbeg 10 is comprised of a mixture of Argbeg casks aged 10 years and longer. This enables the producer to create a consistent taste profile from bottle to bottle, year to year, accounting for such variables as barley variety, climate, peating, etc.

Indy bottlers generally do not vat as described above. They release single cask or single year expressions. They are not trying to create a consistent taste profile. In fact the advantages of drinking indy bottlings is that it’s inconsistent (sometimes in a good way) with the distillery bottling—even of the same age expression. Indy bottlers may take possession of casks, storing them in a different type of climate than the distillery casks. With scotch being comprised of primarily water, the water used to dilute the cask at bottling is often different. And bottled alcohol levels can also vary between distillery bottled and indy bottling. All of these variables play a significant role in effecting the whisky’s profile.