What happens in a distillery?

Malting makes the starch in barley accessible. The grains are soaked in water and then laid out to germinate for six to seven days, releasing enzymes that can convert starch into sugar. Germination is stopped by drying the barley over a fire below 70 degrees. If peat is put on that fire, the malt absorbs smoke, and that smoky character remains recognisable in the bottle.

The dried malt then goes through the mill. According to the Scotch Whisky Regulations 2009, with Scotch only whole grain of other kinds may be added to the malted barley; single malt may contain no other grain at all.

Mashing converts starch into fermentable sugar, and that only works within a narrow temperature band. In the mash tun the ground malt goes in with hot water, in three successive additions of water that start around 67 degrees and rise to just below boiling point. The enzymes from the malting do the work: too hot and they break down, too cold and they do not get going.

The result is called wort. The Scotch Whisky Regulations 2009 require that mashing, the conversion of starch by the malt’s own enzymes, and fermentation all take place at the same distillery in Scotland. A distillery may therefore not buy ready-made wort.

Yeast converts the sugars from the wort into alcohol. The wort first cools to about 20 degrees and then goes into the washback with yeast. After about two days the fermentation settles and the wash contains 6 to 8 percent alcohol. In strength that resembles beer, but there is no hop in it.

The law leaves little room. With Scotch the wort may only be made fermentable by the malt's own enzymes, and fermentation may only be started by adding yeast. Other processing aids are not permitted.

Malt whisky is distilled twice in Scotland, in copper pot stills. The first still is called the wash still and takes the alcohol from the wash. The second, the spirit still, separates the run into foreshots, heart and feints; only the heart is collected, at about 68 percent alcohol.

The law sets an upper limit. Scotch must be distilled at less than 94.8 percent alcohol, so that the colour, aroma and taste of the raw materials and of the production process remain recognisable. Above that limit one speaks of neutral alcohol, and then it may no longer be called whisky. Grain whisky made from wheat therefore tastes different from grain whisky made from corn.

Maturation is fixed by law for Scotch. The spirit must mature for at least three years in Scotland, in oak casks of no more than 700 litres, in a bonded warehouse or another permitted location. The three-year limit dates from 1915. The 700-litre cask limit matches the largest trade size common at the time, the sherry gorda.

At bottling the minimum is 40 percent alcohol. Only water and plain caramel colouring may be added. During maturation up to about 2 percent evaporates from the cask each year, the part known as the angels' share. Many single malts spend 8 to 12 years or longer in cask.

According to the Scotch Whisky Association, Scotland counted 154 working distilleries in May 2026. In the warehouses roughly 22 million casks lie maturing, together good for about 12 billion bottles of 70 centilitres.

Exports came to 5.36 billion pounds in 2025. Every second, 43 bottles of 70 centilitres at 40 percent cross the border, to more than 160 markets, together well over 1.3 billion bottles a year. In Scotland more than 41,000 jobs depend on the sector, and in the rest of the United Kingdom another 25,000.