I ran across this excellent article that got me thinking some more about the types of barrels that can be used in the production of single-malt Scotch whisky. There are several other online resources that also cover the usage and sizes of whisky (and other types of) barrels.
The maximum capacity of a barrel in which Scotch can be legally aged is 700 liters. It’s the law! The first-mentioned article says that such a barrel is called a “Gorda” but it’s difficult to find many references to that name in the context of barrels, whisky or otherwise. The 700-liter barrel size is definitely mentioned, just not the name “Gorda.”
The next size down is 500 liters, the capacity of the Sherry “butt” (no, really, that’s what it’s called…) and the similar-capacity “Port pipe,” and then the 250-liter “hogshead,” the 225-liter barrique bordelaise (commonly used in wine production), the 125-liter “quarter-cask” (indicating that the “standard” cask is likely 500 liters…) and finally the 90-liter barrel (which may or may not be involved in the production of Scotch whisky, but it is a common size).
So we have the following:
- 090 liters (24 gallons; Tuthilltown Spirits uses smaller casks than this in aging its American whiskeys)
- 125 liters (quarter-cask, as used for finishing certain Laphroaig whiskies)
- 225 liters (barrique bordelaise)
- 250 liters (hogshead)
- 500 liters (Sherry butt, a.k.a. “puncheon”)
- 500 liters (Port pipes; similar capacity to Sherry butt, but different shape)
- 700 liters (Gorda, allegedly)
This isn’t just trivia. Large-capacity barrels have less surface area in contact with the liquid, so they contribute less flavor from the wood (in a given amount of time) compared to smaller barrels. Depending on the effect desired, a smaller cask may be chosen for the more intense flavors it could impart (again, given an equivalent time in the barrel), or perhaps the desired intensity of flavor could simply be achieved in a shorter time than would be required in a larger barrel.
On the other hand, the larger barrels may contribute more subtlety to the liquid that would be difficult to achieve in a smaller barrel. In practical terms, using smaller barrels also means you have to handle and track the inventory of many more barrels in order to hold the same amount of liquid, so there are logistical tradeoffs as well related to the choice of barrel size.
These variables, and the choices of the whisky makers as to the amount of time the spirit spends in each type of barrel while it is aging, give each whisky its unique flavor profile. (Of course, the type of still and the mash bill contribute significantly to the flavor profile as well, but this article is about barrels!) To get consistent results over time, distillers have to carefully manage perhaps thousands or tens of thousands of barrels and ensure that the types, sizes and previous contents match the product that they are trying to create. They have to ensure that their source of barrels is reliable for time spans on the order of decades. A barrel can only be used so often before it must be recycled, so there is an ongoing management process involving inventory of each and every barrel. The job of wood management is arguably one of the most important, and least appreciated, jobs in the entire production process of single-malt Scotch whisky.