How whiskey is made
Up to 45 litres of whisky can vanish from a cask in four years, and distillers call that loss the angel's share.
- stations
- 7
- things upstream
- 26
- raw sources
- 13
- steps from the ground
- 6
The short version
Whiskey is distilled beer. Grain is malted or cooked, mashed into a sweet liquid, and fermented with yeast. The weak, beer-like wash is boiled in a still, and the vapor is condensed into clear spirit. That spirit is then matured in oak casks, where it picks up color and flavor, before being diluted and bottled.
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Sprout and dry the grain
For malt whisky, barley is soaked, allowed to sprout and then dried with hot air to halt germination. Sprouting makes the enzymes that will convert starch into sugar.
three days of soaking
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Mash in hot water
The ground malt is stirred into hot water in a mash tun, and its enzymes turn starch into sugar. Bourbon starts with a mash that is at least 51% corn.
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Ferment to a wash
Yeast is added to the sweet liquid, which then ferments into a mildly alcoholic liquid called wash. It resembles a strong beer, and needs to go to the still before it spoils.
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Boil it in the still
The wash is heated in a copper pot still or a column still. Alcohol boils off before most of the water, and the vapor is condensed. Distillers keep the middle of the run, called the heart, and send the first and last portions back. Copper pulls out sulfur compounds that would taste unpleasant.
70–80% ABV off a pot still
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Fill the oak casks
The clear spirit goes into casks. American whiskey must be aged in new charred oak, while many Scotch casks are reused. Oak adds vanillin and other compounds that give color and flavor.
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Wait for maturation
Over the years, the spirit extracts compounds from the wood, loses some of its harshness and slowly evaporates. Scotch whisky must be matured in oak casks in Scotland for a minimum of three years.
3 years minimum for Scotch
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Blend, dilute and bottle
Casks of different ages are vatted and diluted with water to bottling strength, commonly 40% alcohol by volume. Whisky does not age further once it is in the bottle.
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Worth repeating
- Whisky takes its name from the Gaelic word for water, uisce or uisge.
- A column still can reach a vapor strength of 95.6% alcohol, which is the most that alcohol and water can reach by simple distillation.
- Aeneas Coffey patented his column still in 1831, making distillation cheaper and more efficient.
Back to the ground
Follow every input upstream and whiskey starts as these 13 raw sources.
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Sources
Cite this page: "How whiskey is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/whiskey