Size matters! Especially with whisky casks

We all know that with many things in life, size matters and whether you like it or not, that's just the way it is. Especially when it comes down to whisky barrels because the size of the barrel has a direct impact on the strenght, the taste and even the quality of the whisky.

There are several factors that determine the impact of cask size on whisky, including the surface area to volume ratio, the rate of evaporation, and the amount of wood contact. Let's take a closer look at each of these factors.

Surface Area to Volume Ratio

The surface area to volume ratio refers to the relationship between the surface area of the cask and the volume of whisky contained within it. In general, the smaller the cask, the larger the surface area to volume ratio. This means that there is more surface area of the cask in contact with the whisky, which can accelerate the maturation process.

For example, a small cask like a bourbon barrel (which has a capacity of about 200 liters) will have a larger surface area to volume ratio compared to a larger cask like a hogshead (which has a capacity of about 250 liters). This means that the whisky in the bourbon barrel will mature faster and will have a more intense flavor compared to the whisky in the hogshead.

Rate of Evaporation

Another factor that determines the impact of cask size on whisky is the rate of evaporation. This refers to the amount of whisky that is lost to evaporation during the maturation process. In general, the smaller the cask, the higher the rate of evaporation.

This is because smaller casks have a higher surface area to volume ratio, which means that there is more surface area exposed to the air. This accelerates the evaporation process, resulting in a higher rate of evaporation. As a result, the whisky in smaller casks will have a more concentrated flavor and will be more intense compared to the whisky in larger casks.

Amount of Wood Contact

The amount of wood contact is another factor that determines the impact of cask size on whisky. This refers to the amount of contact between the whisky and the wood of the cask. In general, the smaller the cask, the more wood contact there will be.

This is because smaller casks have a higher surface area to volume ratio, which means that there is more surface area of the cask in contact with the whisky. As a result, the whisky in smaller casks will have a more intense woody flavor compared to the whisky in larger casks.

What sizes are out there anyway?

There is a large variety of sizes available and they differ a lot.

This is a short list of the different ones out there, from smallest to largest:

• Firkin - 41 ltrs

• Bloodtub - less than 50 ltrs

• Quarter Cask - 50 ltrs

• Rundlet - 70 ltrs

• British Barrel - 160 ltrs

• ASB Barrel - 200 ltrs

• (Bordeaux) Barrique - 225 ltrs

• Hogshead - 250 ltrs

• Cognac Cask - 300 ltrs

• Puncheon - 350 ltrs

• Butt - 500 ltrs

• Pipe - 650 ltrs

• Drum - 650 ltrs

• Gorda - 700 ltrs

• Tun - 982 ltrs

Just to remind you, in case you didn't know, Scotch whisky can only be matured in a casks that is no larger than 700 litres, so while you may not come across many Drum or Gorda casks out there, they are still used. Mostly you will see distillers use a Bourbon (or ASB) Barrel, Butt or Hogshead.

Personal preference

Overall, the size of a whisky cask can have a significant impact on the flavor and characteristics of the whisky. Smaller casks will result in a more intense and concentrated flavor, while larger casks will produce a smoother and more nuanced whisky. Ultimately, the size of the cask is a matter of personal preference and can be used to create a wide range of flavor profiles in whisky.