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Whisky

From barley to glass

Every whisky starts as grain, water and yeast. What turns them into a smoky Islay malt, a sweet bourbon or a Japanese blend is a chain of choices: how the barley is dried, the shape of the stills, the casks and the years. Here is how it works, step by step.

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A short history

The water of life

Distilling reached Ireland and Scotland in the Middle Ages, most likely through monasteries, where it was used to make medicines. The spirit was called aqua vitae, ‘water of life’, in Gaelic uisge beatha; over the centuries uisge became ‘whisky’.

1405An Irish chronicle records a chieftain who died at Christmas after ‘a surfeit of aqua vitae’.
1494First written record in Scotland: malt given to Friar John Cor ‘wherewith to make aqua vitae’.
1823After decades of heavy taxes and smuggling, the Excise Act makes licensed distilling worthwhile. Many famous distilleries date from these years.
1830Aeneas Coffey patents the column still. Light grain whisky makes blends possible, and blends carry Scotch around the world.
1920–33Prohibition shuts almost every distillery in the United States. When it ends, bourbon has to start again from empty warehouses.
1923Shinjiro Torii founds Yamazaki, Japan’s first malt whisky distillery. Its first manager, Masataka Taketsuru, had learned the craft in Scotland.

How it’s made

Seven steps from barley to bottle

Malt whisky is still made in batches, much as it was two centuries ago. The steps below follow a Scotch single malt; where grain whisky or bourbon does things differently, we say so.

01
Malting
Barley can’t be fermented as it is: its starch is locked away. So it is soaked in water, then spread out to sprout for about five days. On a traditional malting floor the maltmen turn it with wooden shovels so the shoots don’t tangle and the heat stays even. Sprouting wakes up the enzymes that will later turn starch into sugar.
Most distilleries now buy their malt from specialist maltings. A few, such as Springbank, Laphroaig and Bowmore, still malt some or all of their own on the floor.
5days for the barley to sprout
02
Kilning & peat
The sprouted ‘green malt’ is dried in a kiln to stop it growing. The pagoda roofs that still crown many distilleries were built to vent these kilns. Feed peat to the fire while the malt is damp and the smoke clings to the husks, leaving phenols that taste of bonfire, iodine and tar.
Peating is measured in phenol parts per million (ppm) in the malt. Most Speyside and Highland malt has little or none; Islay heavyweights such as Laphroaig, Lagavulin and Ardbeg use malt at roughly 35–55 ppm. It’s a guide, not a promise: much of the smoke is lost on the way to the bottle.
35–55ppm for classic Islay smoke
What is peat?
Peat is the soil of a bog: moss, heather, grasses and roots that never fully rot, because the waterlogged ground keeps the air out. It builds up by about a millimetre a year, so a bank a few metres deep has taken thousands of years to form. Cut in spring and dried through the summer, it burns slowly with a thick, fragrant smoke. Islay peat, rich in sphagnum moss and salted by sea spray, smokes differently from the woodier peat of the mainland. Cutting peat is debated for environmental reasons: bogs store a great deal of carbon, and draining them releases it. But whisky uses less than 1% of the peat dug in Scotland, most of the rest goes into garden compost, and several distilleries now fund bog restoration.
03
Milling & mashing
The malt is ground into grist and mixed with hot water in a mash tun. Water runs through it in up to three rounds, each hotter than the last, while the enzymes convert the starch into sugar. The sweet liquid drawn off is the wort; the spent grain, the draff, goes to feed cattle.
Bourbon is different: corn, rye or wheat and malted barley are cooked together, and the grain usually stays in the mash all the way to the still.
3waters, each hotter than the last
04
Fermentation
The cooled wort goes into washbacks, tall vats of Oregon pine or stainless steel, and yeast is added. Within hours it froths as sugar turns into alcohol and carbon dioxide; a rotating arm, the switcher, keeps the foam down.
Two to four days later the wash is ready: a rough, beery liquid of about 8% alcohol. Long fermentations tend to give fruitier, lighter spirit, one of the quiet choices behind a distillery’s style.
8%alcohol in the wash
05
Distillation
Distilling separates the alcohol from the water and concentrates the flavours. Copper does more than carry the heat: it strips out sulphur and leaves the spirit cleaner. Two kinds of still do the work.
70%new make off the spirit still
Pot stills, in batches
Malt whisky is distilled twice. The wash still makes ‘low wines’ of roughly 20–30%; the spirit still takes them to about 70%. The stillman keeps only the heart of the run, watching it flow through the locked brass spirit safe; the first and last parts, heads and tails, go back into the next batch. Tall, slender stills give light, fruity spirit, short squat ones a heavier, oilier one. Irish pot still whiskey is traditionally distilled three times.
Column stills, non-stop
Patented by the Irishman Aeneas Coffey in 1830, the column still runs continuously: wash trickles down over perforated plates while steam rises through it and carries the alcohol across to a second column, the rectifier. It makes lighter spirit in large volumes, the grain whisky behind most blends. Bourbon is usually made in a column, often with a second pass in a ‘doubler’, and must come off the still at no more than 80% (160 proof).
06
Maturation
New make goes into the cask clear, usually brought down to about 63.5%, and comes out golden years later. The wood adds colour, vanilla and spice and softens the harsh edges, while the little air that seeps through the staves slowly rounds the spirit. Scotch, Irish and Japanese whisky must spend at least three years in casks of no more than 700 litres.
Casks rest in warehouses: low, damp dunnage sheds with stone walls, earth floors and casks three high, or tall racked buildings. In Scotland about 2% evaporates each year, the angels’ share. In Kentucky’s hot summers, or in India and Taiwan, the angels take far more and whisky matures faster.
2%a year to the angels
Charred oak
Bourbon must go into new, charred oak barrels. Coopers fire the inside for roughly 15 to 55 seconds; the heaviest common level, No. 4, cracks into ‘alligator’ char. The charcoal filters the spirit and the toasted wood beneath gives vanilla and caramel. A barrel can hold bourbon only once, which is why most Scotch matures in ex-bourbon American oak, and much of the rest in European oak that held sherry, for dried fruit and spice.
Cask sizes
The smaller the cask, the more wood each litre touches and the faster it matures. Common sizes: quarter cask about 125 litres (or 50), barrel about 200, hogshead about 250, butt or puncheon about 500. The legal maximum for Scotch is 700 litres.
07
Bottling
When the whisky is ready, casks are emptied, married together and usually brought down with water to bottling strength: at least 40% by law, often 43 or 46%. Cask strength means no water added, often well over 50%.
Many whiskies are chill-filtered, cooled so the fatty compounds that can cloud them are filtered out. Non-chill-filtered whiskies keep them, and many say more texture with them. Scotch may add only water and plain caramel (E150a) for colour, nothing for flavour. And an age statement always gives the age of the youngest whisky in the bottle.
40%minimum bottling strength

Styles

One word, many whiskies

Whisky is a family, not a single drink. The words on the label tell you what went into the bottle and how it was made.

Single malt

Malted barley only, pot stills, a single distillery. Scotland’s best-known style, now made from Ireland and Japan to India and Sweden.

Learn about Scotch →

Single grain

One distillery, but other cereals such as wheat or corn alongside malted barley, usually from column stills. Lighter, often aged long.

Blended malt

Single malts from several distilleries married together, with no grain whisky.

Blended whisky

Malt and grain whiskies from several distilleries. The blender’s art, and the way most Scotch is drunk.

Single pot still

Ireland’s own style: malted and unmalted barley, at least 30% of each, distilled in pot stills. Creamy and spicy.

Bourbon & rye

American whiskey from at least 51% corn (or rye), aged in new charred oak: vanilla, caramel, spice.

Bourbon guide →

Japanese

Distilled in Japan since the 1920s on the Scottish model, known for finely tuned blends and rare Japanese oak, mizunara.

World whisky

Sweden, India, Israel, France, Taiwan: new distilleries, new climates, new casks. On our shelves: Mackmyra, Paul John, Milk & Honey, Armorik and more.

The rules

What the label promises

Each whisky country protects its name. The headline rules, simplified:

Scotch whisky

Scotch Whisky Regulations 2009

Made in Scotland from cereals, water and yeast only
Distilled to less than 94.8% alcohol
Matured in Scotland in oak casks of 700 litres or less, for at least 3 years
Bottled at 40% or more; only water and plain caramel may be added
An age on the label is the age of the youngest whisky

Irish whiskey

Irish Whiskey technical file

Distilled and matured on the island of Ireland
At least 3 years in wooden casks of 700 litres or less; oak is not required
Four styles: pot still, malt, grain and blended
Pot still: at least 30% malted and 30% unmalted barley

Bourbon

US federal standards, 27 CFR 5

Made in the USA from at least 51% corn
Distilled to no more than 80% (160 proof)
Aged in new charred oak, filled at no more than 62.5% (125 proof)
Bottled at 40% (80 proof) or more; no colouring or flavouring
‘Straight’ bourbon: at least 2 years old

Japanese whisky

JSLMA labelling standard, 2021

Malted grain always used; water from Japan
Mashed, fermented and distilled at a distillery in Japan
At least 3 years in wooden casks of 700 litres or less, in Japan
Bottled in Japan at 40% or more
A voluntary standard for the association’s members, in full force since April 2024

A simplified summary; the full texts go into more detail.

Words to know

A short whisky glossary

Cask strength: Bottled straight from the cask, without adding water. Add your own, a few drops at a time.
Single cask: Whisky from one cask only, bottled on its own. Every cask is a little different, so bottles are often numbered.
NAS: No age statement. Still at least three years old; the producer just doesn’t print the age of the youngest whisky.
Finish: A few months to a couple of years in a second cask (sherry, port, rum, wine) after the main maturation.
First fill: A cask used for whisky for the first time since it held bourbon or sherry. It gives more flavour than a refill cask.
ppm: Phenol parts per million: how heavily the malt was peated. Higher usually means smokier, but not always.
The cut: The part of the spirit run the stillman keeps, the heart. Heads and tails are distilled again.
Angels’ share: Whisky lost to evaporation through the cask: about 2% a year in Scotland, much more in hot climates.
Chill filtration: Cooling and filtering whisky so it stays clear in the cold or with ice. ‘Non-chill-filtered’ means it was skipped.
Mash bill: The recipe of grains, mostly used for bourbon and rye, for example 75% corn, 13% rye and 12% malted barley.

How to taste

Five steps to a better dram

Choose the glassA tulip-shaped nosing glass gathers the aromas. Keep the tumbler for ice and cocktails.
LookTilt and swirl. Colour tells you more about the cask than the age, and caramel can deepen it.
NoseGently, with your mouth slightly open. Take a first impression, wait a minute, then nose again.
Add waterA few drops open up cask-strength and smoky whiskies. Add, taste, then add a little more.
Taste & finishLet it coat your tongue before you swallow. How long the flavours stay is the finish.

Taste the difference with us: our whisky masterclasses at the shop take you through a flight of whiskies, from malt to cask.

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