How whisky is made: from grain to glass
The complete production process, explained clearly and without shortcuts: malting, mashing, fermenting, distilling and maturing.
- Whisky is made in five stages: malting, mashing, fermenting, distilling and maturing, followed by bottling.
- Making the spirit takes about a week or two. Maturing it takes years.
- Every stage shapes flavour, but the cask has the biggest effect.
- Pot stills make richer spirit. Column stills make lighter spirit.
- Rules differ by country, so Scotch, bourbon, Irish and Japanese whiskies are made in different ways.
The process at a glance
Every whisky starts with grain, water and yeast, and ends in a bottle. In between there are five main steps.
Malting and milling
Barley is sprouted, dried and ground. About a week.
Mashing
Ground grain is mixed with hot water to make a sugary liquid. A few hours.
Fermentation
Yeast turns the sugar into alcohol. Two to four days.
Distillation
The liquid is heated in stills to concentrate the alcohol. About a day.
Maturation
The spirit rests in oak casks for years. At least three years for Scotch.
The ingredients of whisky
Whisky starts with a very short list. What makes each bottle different is how the ingredients are handled.
Step 1: Malting and milling
Barley contains starch, which yeast cannot use directly. Malting starts the process of turning that starch into sugar.
The barley is soaked in water for about two days, then spread out to germinate for several days. The grain begins to sprout, and enzymes develop that can convert starch into sugar. Before the sprouts grow too far, the grain is dried in a kiln with hot air. This stops germination and leaves the malt dry and stable.
If the kiln fire includes peat, the smoke clings to the grain and gives the whisky a smoky character. See peated whisky. Most distilleries today buy malt from large specialist maltings. A few, such as Balvenie, Springbank and Highland Park, still malt some of their own barley on traditional malting floors.
The dried malt is then ground into a coarse flour called grist. It is milled into a mix of husk, grits and fine flour so the mash can drain properly in the next stage.
Step 2: Mashing
The grist is mixed with hot water in a large vessel called a mash tun. The enzymes in the malt convert the starch into sugar, and the sugary liquid is drained off. This liquid is called wort.
The process is usually repeated with water at progressively higher temperatures, often in three stages. The first two waters produce the wort. The third, weaker water is kept and used as the first water for the next mash. The leftover solids, called draff, are normally sold as animal feed.
Whisky made from other grains follows a similar process. Corn, rye and wheat are cooked to release their starch. Distillers often add a small amount of malted barley to provide the enzymes.
Step 3: Fermentation
The wort is cooled and pumped into large vessels called washbacks, which may be made of wood or stainless steel. Yeast is added, and it feeds on the sugars and produces alcohol and carbon dioxide. The mix bubbles and foams for two to four days.
The result is a weak, beer-like liquid called wash, at about 8% ABV. Fermentation also creates many flavour compounds. Distillers often say a longer fermentation produces fruitier, more complex flavours.
Step 4: Distillation
Distillation concentrates the alcohol. The wash is heated in a still. Alcohol evaporates at a lower temperature than water, so the vapour that rises is richer in alcohol. It is then cooled in a condenser and collected as liquid.
Pot stills. These are large copper vessels, used one batch at a time. Scotch single malt is usually distilled twice. The wash still produces a liquid of about 20 to 25% ABV, and the spirit still concentrates it to around 70%. Irish whiskey is often distilled three times.
Column stills. These run continuously and produce a lighter, cleaner spirit. They are used for grain whisky and for most bourbon.
The shape and size of the still affect flavour. Tall, narrow stills tend to make lighter spirit, and short, squat stills tend to make heavier spirit. Copper also removes unwanted sulphur compounds.
In the second distillation the distiller makes cuts. The first part (foreshots) and the last part (feints) are set aside, and only the middle part (the heart) is kept. When to cut is one of the most important decisions a distiller makes.
Step 5: Maturation
The clear spirit that comes off the still is called new make. It is filled into oak casks and left to age. During this time it picks up colour and flavour from the wood, loses harsh edges, and slowly changes in character.
- The cask. Ex-bourbon barrels give vanilla and coconut. Ex-sherry casks give dried fruit and spice. Read more in cask types explained.
- The climate. Whisky ages faster in warm places such as Kentucky and Taiwan and more slowly in cool Scotland.
- The angels' share. A small amount, often around 2% a year in Scotland, evaporates through the wood.
- The minimum age. Scotch whisky must be aged for at least three years. Bourbon has no minimum unless it is labelled straight.
For the full story, see maturation explained.
Bottling
When the whisky is ready, the master distiller or blender selects casks and combines them. Most whisky is diluted with water to bottling strength, typically 40 to 46% ABV. Some is chill filtered and has caramel colouring added. Whisky bottled at its natural strength is called cask strength. To make sense of what it says on the bottle, read how to read a whisky label.
How production differs by country
How each stage shapes flavour
How long each stage takes
That means it takes about two weeks to make new spirit, and a distillery has to wait years before it can sell a single bottle of what it makes today.
What the law says in different countries
Each major whisky country has legal rules that protect the name and set a minimum standard. The main ones are summarised here.
Craft and experimental production
Many newer distilleries experiment with parts of the process that large producers tend to standardise. Some grow their own barley on site, such as Kilchoman on Islay. Others use heritage grains, such as Bruichladdich with its Bere barley. Some run very long fermentations, use small stills or mature in unusual casks.
The aim is to make a spirit with a clear sense of place and character. It does not always work, but it is why the whisky scene has so much variety today.
Why whisky takes so long and costs what it does
Whisky is a slow business. A distillery has to buy grain, fuel and casks, then store the spirit for years before it earns any money. Every year a little evaporates, which is called the angels' share, so there is less to sell the longer you wait. Warehouse space, insurance and the cost of tying up money for a decade or more all add up.
That is why older whisky costs so much more. See age statements explained and maturation explained.
A glossary of production terms
How whisky is made: quick answers
How long does it take to make whisky?
Making the spirit takes around one to two weeks from grain to still. Maturing it takes at least three years for Scotch, and often 10 years or much longer for premium bottlings.
Why is whisky aged in oak?
Oak is strong enough to hold liquid and slightly porous, so the spirit can interact with the air. It also contains compounds that give vanilla, spice and sweetness. Over time it softens harsh flavours.
What is new make spirit?
New make is the clear, high-strength spirit that comes off the still before it goes into a cask. It is not yet whisky, and it is usually sharp, grainy and fiery.
Why are copper stills used?
Copper reacts with sulphur compounds in the vapour and removes them. The result is a cleaner, sweeter spirit.
Does whisky keep ageing in the bottle?
No. Whisky only ages in the cask. Once it is bottled, the age on the label stays the same, although an opened bottle changes slowly through contact with air.
Cask types explained
Caskable is for adults of legal drinking age. Please drink responsibly.
