To show a glass of whiskey that contains a particular whiskey cask.

Everything You Need to Know
About Whiskey Casks

Many things go into making whiskey – the quality of the grain, water, and distillation time. But the cask may make or break your whiskey. A whiskey cask can take your drink from passable to exquisite. A perfectly constructed barrel makes a powerful difference. There are many types of barrels. Let us tell you about them! But first…

What Are Whiskey Casks Made From?

Most distillers believe the cask contributes around 60-70% of a whisky’s flavor, making maturation the most crucial step in its creation. However, the cask’s background affects maturation efficiency. The most common wood for whisky casks is oak, and Scotch and Bourbon must age in it. What makes oak unique? When toasted, the grain releases vanilla, caramel, nuts and is liquid-tight.

Oaks come in over 600 varieties when toasted. Each has unique characteristics to its region of origin. Although most distillers use Quercus alba (American oak) and Quercus robur (European oak), many other varieties, such as Oregon garryana and Japanese mizunara, are for testing. They source the oak sustainably from cooperages that work closely with sawmills, timber suppliers, and forestry commissions to construct casks.


To detail the effect that different types of whiskey casks have on the taste of whiskey.


How are Whiskey Casks Made?

Wooden casks have changed little since they were first invented, but making them has evolved. Despite the fade of collapsible shipping casks and DaVinci-style cleaning machines featured in 18th-century Scientific American, barrels remain examples of both art and science. To get the proper chemical reaction between liquid and wood, coopers adjust the intensity of the char in a barrel by precise amounts. Coopers make casks in different ways, based on the spirit it houses, such as sherry or bourbon.


Here’s An Overview

A 70-year-old tree is ideal for the best results. The cooper splits the oak into long, thin pieces and dries them for several years outside. This process reduces the harsh tannins of the wood by removing moisture. After the planks have seasoned, they carefully form them into whiskey aging staves.

Coopers fashion the staves into a skirt-like structure by tying their ends around an iron hoop. Fire is then used to bend the staves into shape, a process known as toasting. The wood’s sugars caramelize during toasting, producing flavors such as caramel, nuts, and licorice. This breaks down the wood’s lignin into compounds such as floral, vanilla, and spice. As you toast, the level of intensity varies – light, medium, and heavy.

Last, applying the cask head. After drilling the hole for the spirit to be poured into, add the final hoops. Having completed these steps, the cask is now ready to be filled with new whisky and begin its three-year journey to distillation.

  • Cask usage – As the cask ages, it imparts less flavor



  • Cask time – the more time extracts more flavor


  • Spirit intensity – wood influences a lighter balance than a heavier balance


To list and describe the most common whiskey cask types.


Life After Whiskey for Casks

How do people use them? Different places have different answers. A good example is Glenmorangie’s Beyond The Cask program, where the whiskey brand collaborated with wooden bicycle manufacturer Renovo to create a bespoke machine using whisky casks. Glenmorangie also teamed up with British eyewear designer Finlay & Co to create whisky barrel-wood sunglasses, and Irish brand Bushmills developed headphones with Grado Labs.

According to American law, big whiskey producers can only use the barrels once and only fresh oak barrels. As soon as this cask is empty and the whiskey bottled—two-three years—it’s worthless in the American system.

It seems wasteful, but it presents an excellent source of casks to other markets that prefer the smoother, more subtle taste of seasoned oak. They include whisky producers in Ireland, Japan, Scotland, and other spirits producers–tequila and rum industries–and the wine industry.

They serve another 50-60 years, three to four times. 

But what happens when the cask is dead and no longer usable? Many companies sell off spent barrels cheaply, and they are then turned into a variety of products, such as:

  • The ‘whisky oak chips’ you throw on your barbecue


  • Upturned barrel tub at the garden center is perfect for bedding plants


  • Candleholder for your mantelpiece


  • Bespoke furniture, ornaments, or sculpture


After half a century of service, they deserve a better retirement. Join us at The Flatiron Room for some whiskey tasting.