The Whisky Club's Guide to Making Whisky

The Whisky Club guide to making whisky

Whisky casks are more than storage. They’re flavour creators. From the type of oak to the previous contents, every detail influences the aroma, colour, and complexity of your dram.

In this guide, we’ll explain the science behind maturation, explore the main types of oak used in whisky casks, and break down popular cask styles like Bourbon, Sherry, and Port. Whether you’re a whisky enthusiast or just starting your journey, this is your essential resource for understanding how casks shape whisky.

How is whisky made?

Whisky is made by converting grain into beer, then distilling it into a spirit that must spend time in a wooden cask to mature.

There are thousands of whisky brands on the shelves these days, each one having a unique flavour profile that's a result of location, production equipment, production techniques and whiskymaking philosophies. Here we will show you how whisky is made. For ease, we will use the Scottish spelling of whisky as the generic term, substituting whiskey where appropriate.

To help you continue your whisky adventure, The Whisky Club aims to highlight the unique selling points of any of the whiskies we feature. Sometimes these are related to exclusivity, other times they will be down to deliciousness and more often than not they will include some whisky jargon. So let us be your guide and help you differentiate your malts from your grains, your barrels from your butts, and your mills from your mash tuns. This is The Whisky Club’s guide to making whisky.

Making whisky involves 8 steps:

1. Malting - prepares the grain for the conversion of starch to fermentable sugars
2. Milling - accessing the starch by grinding the grain into flour
3. Mashing - adding water to firstly convert the starch to fermentable sugars and secondly extract it by dissolving it
4. Fermentation - adding yeast or another catalyst to convert the sugar into alcohol
5. Distillation - concentrating the alcohol from about 8% ABV to up to 95% ABV
6. Maturation - ageing in wood to remove unwanted youthful notes and introduce natural colour and flavours from the cask
7. Blending - mixing different casks together to achieve a desirable flavour profile
8. Bottling - packaging the whisky for our shelves

For more information on the ingredients used in the whiskymaking process, check out The Whisky Club's guide to whiskymaking ingredients. For a more in-depth look at casks, check out The Whisky Club's guide to casks. 

The whiskymaking process – in depth

Here we break down the 8 steps of whiskymaking listed above.

No matter where you are making whisky, the basic process is the same. The choices made throughout this process are levers whiskymakers have to pull to make something distinctive and unique. 

1. Malting

Malting is the process of modifying the grain to create and stimulate enzymes within. These enzymes are vital for breaking starch into sugar during mashing. Not all cereals are malted. The goal is to emulate the growing cycle in the field and awaken the grain.

Steeping – to kickstart the process of malting, the grain is soaked on and off in water over the course of a couple of days. This causes the grain to sprout.

Germination – the grain is then turned in a drum or on a traditional malting floor to continue to grow. The turning process stops the roots from creating a carpet and regulates the temperature. During this process the cell walls and proteins in the barley are modified, and we are left with enzymes and starch. Left to its own devices, the grain would continue to sprout and grow using up the sugar source within.

Kilning – the germination process is arrested by the introduction of heat. This stops the grain at the optimum moment for enzyme and starch content. It is at this point that some distilleries will introduce aromatic smoke (often from burning peat) to their grain to create new flavour profiles. Ever wondered where your peaty Scotch gets its flavour? It’s in the kiln.

The process of malting is vital in the production of Scotch whisky and Irish whiskey as neither industry permits the addition of enzymes in the making of whisky.

2. Milling

Once dried, the grains need to be milled. This gives the brewer access to the starches or sugars inside. The resulting ground cereals is known as “grist”. Both roller and hammer mills are used in distilleries depending on the grain. For single malt whisky, the vast majority of distilleries use roller mills.

3. Mashing

Now we have access to all the good stuff within the cereal, we need to treat it carefully to maximise the amount of sugar we get from it. In the mashing process, the grist is introduced to hot water. Here the enzymes will go to work. They will take the long chain starches and carbohydrates and break them down into fermentable sugars. And the more sugar we can create here, the more whisky we create at the end. It is worth noting that different cereals have different temperature thresholds for mashing. The temperature of water is vital to enzyme activation, with brewers and distillers diligently controlling this part of the process to maximise yield.

When the mash has rested and the water is saturated with sugar, distillers can then add further waters to extract as much sugar as possible. The end result is a sugary liquid called “wort” (short for worthy liquid). This will be cooled and readied for fermentation. Again, the temperatures of the water will have an impact on yield and flavour profile.

4. Fermentation

Fermentation involves the addition of yeast to the wort. Pitched at the correct temperature, the yeast will take fermentable sugars and convert them to alcohol, carbon dioxide and heat over a period of typically 2 to 10 days, depending on the product. This creates a beer (known as wash) that is between 5 and 10% alcohol by volume. Yeast types, pitch temperatures and length of time in the fermenter (known as a washback) will all play a part in flavour creation. Similarly, the material the fermenter is made from will have an impact on the flavour of the beer and subsequently the whisky.

5. Distillation

Once the wash has fermented, we need to concentrate the flavours created. This is simply done in large kettles known as stills. Because ethanol boils at a lower temperature than water, it rises as a steam within the still, leaving the water behind. It is then passed through a condenser, turning it back into a liquid that can be anywhere between 20% and 94.5% ABV. The stills are often made from copper which acts as a catalyst removing sulphury compounds and impurities from the spirit.

There are two main types of still used in whisky production today:

• A pot still is the one we usually imagine when thinking of whisky. They look pear-shaped and work like a kitchen kettle. Beer or spirit is put into the base, the still is turned on and the vapour rises up the inside until all the alcohol is boiled off and the water and waste products (known as pot ale or spent lees) are left behind. The resulting new make spirit is around 72% ABV after two distillations. These work in a batch process producing a glass of whisky every three seconds. The height and shape of the stills are often unique to distilleries and play a part in the final flavour profile. Taller stills allow only the lightest notes over into the final spirit, creating a more delicate profile, whereas short stills let heavier, oilier flavours over creating a more robust style.
• A column still uses a continuous process, similar to that found in an oil refinery. They are often four storeys high or more and consist of plates that work to separate the spirit into different fractions. These stills are continuously fed with wash and can continuously produce spirit at 94.5% ABV. They will deliver about ten bottles per second. Distillers can select what fraction (or alcohol content) to separate for their final product. A Scotch grain whisky will likely be in the 94% ABV range, whereas a Bourbon distillery will remove spirit at a maximum of 80% ABV.

6. Maturation

To call anything a whisky, it must spend some time ageing in wooden vessels. The period of time and wood in question depends on the industry. Here the whiskymaker can play with wood type, heat treatment, cask size, previous contents, length of maturation time, maturation location and number of uses a cask has gone through to create unique and interesting flavour profiles. You can delve deeper into casks with The Whisky Club's guide to casks.

7. Whiskymaking and blending

After maturation in wooden casks, the whisky is almost ready. But a whiskymaker still has decisions to make.

• Will they mix different casks together to create a new flavour profile?
• Will they mix different casks to deliver a new batch of an existing product?
• What strength will the whisky be released at?
• Will they put the whisky through any filtration to remove haze?
• Will they blend for a consistent colour, or add artificial colouring?
• Will they blend and then marry the whisky or send it straight to the bottling line?

The art of blending utilises sensory skills, technical know-how and the ability to plan for the future, because every cask released now is one that is not going to continue to age.

8. Bottling

When the whisky is finally ready for bottling, it will be sent to a bottling facility. Here it will be reduced to bottling strength using demineralised water. It will then be filtered if required, then packaged into bottles and cases for shipping to whisky drinkers around the world.

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Whisky making process FAQs

What are the main steps in making whisky?

The key stages are: malting, milling, mashing, fermentation, distillation, maturation, blending, and bottling.

What is the purpose of malting in whisky production?

Malting activates enzymes in the grain that are essential for converting starch into fermentable sugars during mashing.

What is the difference between pot still and column still distillation?

• Pot stills are used in batch distillation and produce rich, characterful spirits. A pot still produces a glass of whisky every three seconds.
• Column stills operate continuously and produce lighter, higher-strength spirits more efficiently. Industrial columns stills are four storeys high and produce 30 bottles in 3 seconds.

What is “wort” in whiskymaking?

Wort is the sugary liquid extracted during mashing. It’s cooled and fermented to produce alcohol. It is believed the term "wort" is short for "worthy liquid". 

How long does fermentation take in whisky production?

Fermentation typically lasts between 2 to 10 days, depending on the desired flavour profile and production style. Some distilleries have pushed this length of time further to explore the differences in flavour.

Why is copper used in stills?

Copper is maleable, conducts heat well and helps remove unwanted sulphur compounds and impurities, improving the flavour and aroma of the spirit.

What is the minimum aging requirement for whisky?

It must be aged in wooden casks. The length of time will depend on the country.

• Scotland, Ireland and Japan - 3 years
• Australia, USA (if labelled straight whiskey) - 2 years

What happens during whisky blending?

Blending involves combining different casks or whisky types to achieve a desired flavour profile, consistency, or style. It’s both a science and an art.

Is whisky filtered before bottling?

Often, yes. Most whisky will go through a coarse filter to remove any solids from the liquid. Many then go through a process of chill filtration which removes haze-causing compounds, though some producers skip this step to preserve mouthfeel and flavour.

How long does it take to make Scotch whisky?

The process in a distillery takes about a week, then legally, Scotch must be aged for at least 3 years in oak casks. However, the full process — from malting to bottling — can take several years or even decades depending on the desired flavour profile and age of the final product. A twelve year old Scotch for example, must spend minimum 12 years in an oak cask before bottling.

What is the difference between distillation and fermentation in whiskymaking?

• Fermentation is the process where yeast converts sugars into alcohol.
• Distillation follows fermentation and involves heating the liquid to separate alcohol from water and impurities, concentrating the spirit.

What is “new make spirit”?

New make spirit is the clear, unaged alcohol that comes off the still before it’s matured in casks. It’s the raw form of whisky and gives insight into the distillery’s house style. This house style is affected by peat level in the kiln, fermentation time, yeast strains, still size, still shape and distillation processes.

What does “cask strength” mean?

Cask strength whisky is bottled directly from the cask without dilution. It typically has a higher ABV (often 50–65%) and offers a more intense flavour experience. Most whiskies on the market will have demineralised water added to bring it to a consistent alcohol level of 40-50% ABV depending in the product.

What is the angels' share?

The angels' share refers to the portion of whisky that evaporates from the cask during maturation. This is typically around 2% of the volume of the cask per year in Scotland. It’s a natural part of the ageing process.

What is a whisky finish?

A finish is when whisky is transferred to a different cask type (e.g. Sherry, Port, wine) for a short period after initial maturation to add extra flavour complexity. Balvenie Doublewood, Glenmorangie Lasanta and Lagavulin Distiller's Edition are examples of whiskies with cask finishes.

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