Scotch whisky whisky used. An age statement on the bottle, in the form of a number, must reflect the age of the youngest whisky used to produce that product. A whisky with an age statement is known as guaranteed age whisky. Scotch whisky without an age statement may, by law, be as young as three years old. In the early 21st century, such "No age statement" whiskies became more common, as distilleries responded to the depletion of aged stocks caused by improved sales. Labels may also carry various declarations of filtration techniques or final maturation processes. A Scotch whisky labelled as "natural"
Cask strength on storage conditions. Scotch whisky is typically aged in used barrels, and due to the relatively cool climate in Scotland, the proof level typically stays the same or goes down during maturation. In contrast, American bourbon whisky is produced using new barrels, and storage conditions in Kentucky and Tennessee where nearly all of it is produced allow the proof levels to rise during aging. The vast majority of whisky bottled has been watered down to about 40–46% ABV, although some whiskies marketed for whisky enthusiasts are bottled at proof levels all the way up to cask strength. In the United