The Journey From Barrel to Bottle

Whiskey Barrel Ageing 101: How Long Does Whiskey Take to Age?

There are many symbols we use each day to represent certain aspects of life. We use an envelope to illustrate email, or a knife and fork to depict food. These are easily identifiable images that are explicitly linked to an entity which instantly makes us realise what is being communicated.

And so with this in mind, if we needed a symbol for whiskey, what might we use?

If you immediately thought of a barrel, then you’re one of many. The barrel is surely an icon due to its significance throughout the history of whiskey. Barrel ageing is integral to whiskey creation, and a key part of a whiskey’s identity. At Jameson, we even have our Barrelman emblem, as a recognition of how important that barrel is in our product.

So why is the barrel so important? What does the term barrel aged whiskey even mean and why does barrel ageing whiskey over any other method make any difference at all?

Luckily, our experts in Midleton have all the answers to any questions you’ve ever had when it comes to whiskey barrel ageing, so let’s find out what it’s all about!

How is Whiskey Aged?

Before we answer “How?” we must ask “What?” What does ageing whiskey mean? Simply put, ageing whiskey means leaving newly distilled spirit to sit in a sealed wooden vessel for a long time, often years.
It’s a practice originally born from necessity rather than curiosity. For thousands of years, wooden barrels were used to store and transport all manner of liquids and foods. Recently distilled spirit would have been poured into whiskey barrels, sealed, and put on ships to be sailed elsewhere or kept in cellars and used throughout the year. This method was designed to store spirits for long periods, so naturally, there were barrels that hadn’t been opened for years, but, when they were… hey presto! The clear spirit that entered these (often) oak barrels, emerged as the beautiful amber liquid of complex notes and flavours we know today as whiskey!

Call it oversupply, call it forgetfulness, call it a happy accident, once distillers of spirit knew the impact a few years in a sealed oak barrel had on their product, they too knew that such a process was essential to making their new drink, whiskey.

Today, distillers of whiskey the world over age their product in barrels to impart flavour and colour. Exactly how whiskey is aged differs depending on the whiskey. For Jameson Original, once our new spirit is distilled (which you can read more about here) we take our pot still and grain still spirit and select 2 types of barrels: an American Oak Bourbon Whiskey Barrel, and Oloroso Sherry Cask.

These are known as seasoned barrels, meaning they have been used to store liquid already. In this case American Bourbon, and Spanish Sherry. Our newly made column still, and pot still spirit is  poured into these barrels to age for a minimum of 3 years, but generally Jameson Original sits in the oak barrels of our maturation warehouse for 4 years or more.

As the liquid rests, it begins to soak up all the flavours of the wood and original seasoning. Our maturation warehouses aren’t climate-controlled, so as we cycle through the seasons from hot to cold the barrels slowly expand and contract, breathing incredible depth of flavour into the whiskey.

When it’s time to bottle, our expert blenders combine different barrels together to ensure Jameson’s final flavour is consistent with the high-quality standards we’ve championed since 1780.

What Are Whiskey Barrels?

Whiskey barrels are the oval wooden containers used in storing, transportation, and most importantly, the creation of whiskey. A whiskey barrel can come in many sizes, however, a common barrel to see outside of the maturation warehouse is the American Oak Bourbon Barrel. These are made of American White Oak staves (I.E. carved sections) that have been fitted compactly through skill and steam to create a water-tight drum held together with metal ring hoops, no glue or nails are required!

These barrels are made new for American Bourbon producers, as by law, Bourbon must be matured in unused barrels. The barrels are built, and the interiors charred with open flame, before the spirit is added. When these barrels have been used once to store bourbon, they legally can’t be used again to mature Bourbon .

This is where Jameson comes in! We buy used barrels for our ageing process and use them up to 3 times to mature Jameson Original. Once we’ve had our fun, we sell the barrels again. These barrels go to other distillers or are recycled in other ways. Pubs and bars love to use Jameson barrels as outdoor furniture such as tables. Around Ireland using a Jameson barrel to rest your Jameson Ginger & Lime is a pretty common occurrence!

Check out our full process on How Jameson is Made here.

The Barrel Ageing Process

Barrel ageing is part of the whiskey-making process. Let’s run through the steps of whiskey making and see where the barrel ageing process slots  into the overall journey.

  1. Barley is delivered to the distillery. Some   is malted while some is left unmalted . The barley and malt are milled, combined with water, filtered, and allowed to ferment. The maize we use goes through a similar action, although no malting is required for corn.
  2. Akin to a strong flat beer (which would put Belgian breweries to shame we might add) that results from the process of fermentation is called “Wash.” The wash is collected and distilled in either pot or column stills. Distilling uses heat t to separate the alcohol and flavours from the wash or beer.  Once we’ve distilled 3 times, we’re left with a grain spirit that hovers well above 90% abv (180 proof) or with a pot still spirit which hovers well above 80% abv (160 proof).
  3. Once the spirits have been fully distilled, they are ready to be barrel aged. Oak Barrels are selected from our store and filled with spirit. The barrels are marked, catalogued and stored in one of our maturation warehouses.
  4. Now we wait.
  5. 3 years must pass before we can call it Irish whiskey, yet in practice a minimum of 4 years passes before we are prepared to bottle it as JAMESON. All that time the spirit has soaked up colour and flavour from the bourbon-seasoned barrels and sherry-seasoned butts. Our blenders can now start sampling the whiskey in each cask. Does the whiskey need more time. Is it ready to become part of a blend?
    1. Barley is delivered to the distillery. Some   is malted while some is left unmalted . The barley and malt are milled, combined with water, filtered, and allowed to ferment. The maize we use goes through a similar action, although no malting is required for corn.
    2. Akin to a strong flat beer (which would put Belgian breweries to shame we might add) that results from the process of fermentation is called “Wash.” The wash is collected and distilled in either pot or column stills. Distilling uses heat t to separate the alcohol and flavours from the wash or beer.  Once we’ve distilled 3 times, we’re left with a grain spirit that hovers well above 90% abv (180 proof) or with a pot still spirit which hovers well above 80% abv (160 proof).
    3. Once the spirits have been fully distilled, they are ready to be barrel aged. Oak Barrels are selected from our store and filled with spirit. The barrels are marked, catalogued and stored in one of our maturation warehouses.
    4. Now we wait.
    5. 3 years must pass before we can call it Irish whiskey, yet in practice a minimum of 4 years passes before we are prepared to bottle it as JAMESON. All that time the spirit has soaked up colour and flavour from the bourbon-seasoned barrels and sherry-seasoned butts. Our blenders can now start sampling the whiskey in each cask. Does the whiskey need more time. Is it ready to become part of a blend?
    6. The whiskey is extracted, blended and bottled, or kept and allowed to continue to mature drawing more flavour and character from the barrel to be bottled at a later date, it is transferred to another barrel and finished before it is bottled. A portion of  The whiskey is extracted, blended and bottled, or kept and allowed to continue to mature drawing more flavour and character from the barrel to be bottled at a later date, it is transferred to another barrel and finished before it is bottled. A portion of Jameson Black Barrel is finished in double-charred bourbon barrels and is one of the most complicated blends of whiskey we have.

How Long Does Whiskey Have to Age in Barrels?

How long is whiskey aged in barrels? It’s a great question and more complex than you think. When it comes to ageing spirits, the length of time required for aging whiskey varies depending on place or type of whiskey.
In Ireland, Scotland and Canada whiskey must be aged in oak barrels for a minimum of 3 years. Japan has recently joined this group by specifying, since 2021, that Japanese whisky must be aged in oak for a minimum of three years.
When making American bourbon it’s either 2 or 4 years depending on the type of bourbon being made, and Tennessee Whiskey has no requirement.
These are just the major whiskey producers. Germany, Australia, Taiwan and even Finland produce whiskey on smaller scales and have their own regulations around aging. However, without some ageing in a wooden cask, it can’t really be called whiskey.

At Jameson, most of our whiskey is aged for 4 years or more. Ageing whiskey is like marinating meat or vegetables for dinner. The longer they are left to absorb the marinade, the deeper the wood penetrates and unique flavours form . Jameson 18 Years is a prime example. A deeply rich and nuanced whiskey that has a flavour profile like no other. The special ingredient? Time… also, love. You really need to love whiskey to wait 18 years for it to be ready!

How Barrel Ageing Impacts Whiskey Flavour

In a word? Taste. As you might have guessed at this point in the article, barrel aging has a dramatic impact on whiskey flavour. The process of barrel ageing involves exposing the distilled spirit to the surface area of a wooden barrel over a period of time, impacting the flavour and defining the whiskey. Primarily used as transport and storage containers. The consequence of using these barrels was the transformation of distilled spirit into what we know as whiskey.
If a wooden barrel had no positive effect on the liquid, then today whiskey might be stored in vats made of metal, plastic or glass, and barrel ageing ultimately wouldn’t be a requirement. However, this isn’t the case. The traditional method of using oak barrels lives on, not for their storage value, but for thei r flavour value.
Between 60%-80% of a whiskey’s flavour profile comes from time spent barrel aging. Wood sugars, tannins and lactones seep from the wood into the spirit adding complex flavours and colours and allowing the whiskey to mellow. The charred layer on the inside of barrels helps to remove undesirable sulphur notes which can be a component in newly distilled spirit. The char level strongly impacts the sweet, smoky flavours that can be found in a good whiskey (we’re looking at you Black Barrel).
And finally, we extract flavour from whatever liquid was held in the barrel before us, be it spicy sweetness from the bourbon, or nutty fruitiness from the sherry. These flavours only develop over time, and there is no speeding up the process. However, once the liquid in our barrels is ready to be blended, we can create a whiskey with immense complexity and dept.

Explore our guide on whiskey tasting to make sure you’re fully appreciating every sip.

How Big is a Whiskey Barrel?

Another question that doesn’t have a definitive answer as many sizes of barrel are used to mature whiskey. The standard bourbon barrels that Jameson and American bourbon makers use hold around 200 litres (53 gallons). The seasoned Oloroso Sherry casks that Jameson also uses are much larger, holding 500 litres (132 gallons).

As we mentioned earlier Jameson loves to see our barrels recycled. So, if you wanted a barrel as a piece of garden furniture and you were wondering “How tall is a whiskey barrel?”, ex bourbon is around 36” or 91cm (or a short king a Gen-Z might say) and Sherry casks are usually 51” or 130cm tall.
Unless you and your family play basketball professionally, a bourbon barrel is the ideal height for your outdoor table furniture. And the best part is it comes pre-built! No Allen keys required. Take that Ikea!

What Are Whiskey Barrels Made Of?

Whiskey barrels are made with wood, metal and a lot of skill. Barrel makers are known as coopers but seeing them at work, timber magicians would be a far more accurate name. Coopers shape and ply wooden sections into staves which, when aligned correctly, will form a watertight container. Secured with metal rings and sealed, your barrel is complete.
What wood is used for a whiskey barrel depends on the process, but the vast majority of barrels use European and American oak for its strength and malleability, it’s both breathable and relatively non-porous while being wonderfully hardwearing and full of flavour.

There are of course barrels available made of chestnut, acacia and other woods, but European and American oak is by far the favourite and are the type of wood barrels we use for Jameson Original.

Types of Whiskey Barrels

The most common whiskey barrels are bourbon barrels as they are made consistently and not reused by bourbon makers, resulting in a steady stream of barrels for other whiskey makers to use to mature their whiskey. These are the barrels Jameson uses alongside Oloroso Sherry casks.

There are also barrels known as Hogshead, Butts (don’t laugh), Port Pipe (steady on sailor), and Drums (great for maturing alcohol, bad for a Phil Collins tribute act). Put whiskey in any of these barrels and they become a whiskey barrel. It’s not in name, it’s in the use.

The Best Barrel to Use for Whiskey Ageing

Honestly, at Jameson we think we’ve nailed it with our seasoned Bourbon barrels and Oloroso Sherry casks. The seasoning, size, and materials make these oak barrels second to none when it comes to flavour. If you’re thinking of aging some of your own whiskey, then we can’t recommend our method enough!