Where do whisky casks come from?
What influences whisky maturation?
The cask is as important to a whisky as the spirit itself is. When first filled, the new make spirit is clear and colourless. While a good quality new make will have flavour and character of its own, it will be very different to an aged whisky. And, likely won't have the fully rounded flavours we look for in a good scotch.
When ageing in a cask, there are three factors that influence the final whisky.
- The first element is time. There will be a difference between a whisky aged for 3 years, versus one aged for 30 years. Now that's not to necessarily say one is better than the other. High quality spirit, in a high quality cask, can age quickly. But, the time casks sleep in a warehouse definitely plays a part.
- The second variable is the size of the cask. The size of cask used is a bit like a time machine. A small cask will age a whisky quicker than a large cask. This is because there is a greater surface area. So, you're unlikely to leave a whisky in a very small cask for 30 years. The wood impact would be far too great (if, indeed, there's any left after the angel's take their share). Read more about whisky cask sizes here.
- The third factor is the nature of the cask itself. What type of wood is it? How was the wood treated? And what was held in the cask before the whisky was added. It's this last element that I'm going to look at in this article.
The history of casks used in Scotch
New (often called virgin) oak casks can be used to age whisky. Indeed in America distilleries have to use virgin American oak to age their bourbon by law. But its far more common for Scotch to be aged in a barrel that has previously held another liquid. The two most common examples are bourbon and sherry.
Bourbon is used because all those casks in America have lots of life left in them. By law the US distilleries can't reuse them, so they're shipped to Scotland. Back in the annals of history, it's a similar story with Sherry. Casks of sherry would be imported into the UK. That sherry would be drunk, leaving an empty cask. The canny distillers realised it was a shame to throw those casks away, so they used them to store their whisky. And, they soon found that not only were these economical storage vessels - they actually improved the flavour of their Scotch. You can read more about types of sherry casks used to make whisky here.
Casks used to age single malts
Today, there's a massive variety of casks used to make whisky around the world. Here's a summary of where whisky casks come from:
|2||Beer (inc Stout and IPA)||UK|
|3||Bourbon||Kentucky in the US|
|4||Bourdeaux||Bourdeaux in France|
|5||Calvados||Normandy in France|
|7||Islay whisky||Islay in Scotland|
|8||Madeira||Madeira in Portugal|
|14||Red wine||France, California, Portugal|
|18||Sherry (inc Oloroso and PX)||Spain|
Ageing your whiskies
If you're looking to buy a particular type of whiskey cask, we go to the team at Spiritfilled. They can talk you through the single casks they have available. They can also help you finish your cask. Re-racking whisky from one type of cask to another is a topic I'll cover properly another day. But, Russell and Ross are great, and I'm sure they'd be pleased to help.
If you enjoyed this article, you may enjoy reading this piece about how to become an independent bottler.