Understanding the Different Types of Whisky Casks

At Lochs of Whisky, we believe understanding the different types of whisky casks not only enhances your appreciation of each dram but also helps you make informed choices as a collector or connoisseur. 

From oak types to previous contents, the cask can impart unique flavours, colours and character. Let’s explore the most common whisky casks used in maturation and how they shape the final product.

What are Whisky Casks?

Whisky casks are the wooden vessels used to store, age and transport whisky.  They are usually crafted from oak, valued for its strength, porosity and unique ability to enhance the spirit through interaction. 

Many whisky casks are first used to age spirits like bourbon, sherry or rum. This infuses the whisky with added depth and complex flavour notes. Before they are filled with the new spirit for maturation, the casks are first charred. This is the process of burning the inside of the cask for a short period of time. The depth of this char varies, influencing the flavour to a greater or lesser degree. 

The key reasons behind charring are as follows:

• Caramelisation: Contributing to the whisky's sweetness

• Activated carbon: Absorbing some of the less desirable elements from the spirit

• Releasing tannins: Adding notes of spice, dark chocolate and dried fruits

• Increased surface area: The greater the surface area, the greater the level of interaction between the cask and whisky.

Cask Strength Whisky is bottled directly from the oak cask in its natural and undiluted form. The concentrated flavours, aromas, and alcohol content results in a more complex and powerful drinking experience. Often released in limited quantities, cask strength whisky is highly coveted by enthusiasts and collectors alike.

You can browse a range of our Cask Strength Whisky options here.

Why use Whisky Casks?

It is a legal requirement in the Scotch Whisky Industry to use casks. The Scotch Whisky Association is an official trade organisation representing the Scotch whisky industry. They outline that casks must be matured in oak casks for at least three years, bottled at a minimum strength of 40% ABV and have a maximum distillation strength of 94.8% ABV. 

It wasn’t until 1915 in the UK when it became a legal requirement to age Scotch Whisky. This was due to the introduction of the Immature Spirits Act. This outlined that no British or foreign spirits shall be delivered for restriction on home consumption unless they have been warehoused for a period of at least three years.

Why are Whisky Casks made of Oak? 

Oak is used for whisky casks due to its durability, natural liquid-tight properties and the distinctive flavours it imparts to whisky.

There are two main woods used for whisky casks. These are:

American Oak 

The most widely used cask in Scotch whisky production is the American oak ex-bourbon barrel. Used bourbon barrels from the US are shipped to Scotland for whisky aging. They lend vanilla, coconut, and caramel notes and their tight grain allows for slow, subtle flavour maturation.

Why it matters: Ex-bourbon casks are especially popular for single-malts and are often used in initial ageing before a finish in another cask type.

European Oak

Often sourced from Spain, ex-sherry casks made from European oak are prized for the rich, fruity depth they give to whisky. Casks previously used for sherry impart flavours of dried fruit, spices and nuts. Due to the wood's porosity, the maturation process accelerates, resulting in a richer texture.

Why it matters: Whisky matured in sherry casks tends to have a deeper colour and sweeter palate.

Types of Whisky Casks

Barrel

• Most commonly used in Bourbon production

• Holds 190-200 litres

• This generates 285 standard 70cl bottles

Hoghead

• Often used to age single malt whisky

• Holds 225-250 litres

• This generates 321 to 357 standard 70cl bottles

Butt

• Most common casks used in the sherry industry

• Holds 475-500 litres

• This generates 678 to 714 standard 70cl bottles

Owning a Whisky Cask

It is possible to own whisky casks in the UK. While most Scotch whisky is sold bottled, you can purchase casks either for personal use or as an investment. 

A pivotal change in cask ownership regulation now states that small businesses and even private individuals can now get involved in buying and owning multiple casks of scotch whisky.

The Warehousekeepers and Owners of Warehoused Goods Regulations 1999 was introduced in the UK in 1999 because of concerns over tax fraud. Until March 2025, all warehousekeepers and owners of warehoused goods that were revenue traders had to get permission to own, store, move and trade those goods.

The March 2025 updates removed the OWG (owners of warehoused goods) section so that only warehousekeepers need to register. The updates also removed the need for businesses to go through the lengthy registration process. 

Choosing the Right Cask-Matured Whisky

When browsing our premium selections of Whisky, cask type should be a key consideration. Each cask contributes unique aromas and flavours, offering something special to every whisky lover. 

Whether you're after the creamy sweetness of bourbon or the dried fruit depth of sherry, knowing your cask types empowers your palate.

Ready to find a whisky you’ll love? Check out our full selection of the best whisky here.