You need barrels to make whisky, but few realize just how much they matter. Guyism is all about education, so here are seven things I learned from Highland Park’s Master of Wood, Stuart MacPherson.
I was fortunate enough to spend a week in Scotland with the Highland Park distillery folks and MacPherson was an absolute highlight. Most of this info comes directly from him. Some applies to barrels across the board, and some just to Highland Park.
Whisky is aged in casks, not barrels.
Colloquially a barrel is a perfectly fine term to use, but technically it refers to a specific size. Highland Park doesn’t age anything in barrels, which are 36 gallons. They use hogshead, puncheons, and butts, all of which are larger and have much more awesome names. I’ll continue to say barrels though, because, you know, SEO and stuff.
Size matters.
Small casks provide more contact between the spirit and the wood. This pushes more intense flavor into the spirit, essentially artificially aging it. That’s why you see so many craft distillers using them. Highland Park is so damn good because it features more subtle flavors, which is why they only use larger casks (250 & 500 liters)
60% of flavor in whisky comes from casks.
There’s a reason The Edrington Group, owners of The Macallan, Highland Park and others, owns it’s own cooperage. The wood makes huge difference in the final product. The “garbage in, garbage out” rules still applies, but a great barrel can take a spirit to a whole new level of flavor. Many of the single cask and super premium whiskys you see are plucked from the “honey barrels,” which are typically the top 5%.
Not all oak is created equally.
Spanish oak is the holy grail for scotch, but it comes at a price. I don’t know that price, but it was $800+ in 2010. Spanish oak has wider grain than American, leading to more tannins and color as well as flavors of dried fruit and spice. Highland Park uses predominantly Spanish oak with some American (vanilla and butterscotch flavors) to compliment it.
Wood is aged before becoming a cask.
As fun as it would be, you can’t just chop down a tree and shape it into a barrel. The wood is cut into staves and then either air dried or kiln dried. Highland Park’s barrels are air dried for a ridiculous 4 years to ensure perfection. Air drying makes leaking less likely and pulls more tannins out of the wood, resulting in a softer a spirit in the end.
Highland Park intentionally gets sloppy seconds.
Barrels need to be seasoned before they’re filled with soon-to-be whisky. In the U.S. they’re typically just seasoned with fire because we’re super manly. Highland Park fills their brand spankin’ new barrels with Oloroso sherry for 18-36 months. It will have been nearly six years by the time the barrels get their first taste of whisky. That’s a long wait just for a drink, but it’s nothing compared to the additional 12-40 years you’ll wait for the finished product.
Barrels love to get teabagged.
Scotch’s relationship with its cask is not a one night stand. A certain percentage of every batch is first fill casks, but to get the proper flavor profile, some also comes from refills. Each reuse causes the barrel to impart less flavor, which is known as the “teabag effect.” This allows scotch to age for decades without being overpowered by flavor from the barrel.