Whisky Production

The process begins with barley. The grain is soaked in water for two to three days, allowed to germinate over a period of about a week, and then dried in a kiln to arrest the germination. This is malting, and it converts the starches in the barley into fermentable sugars.

Historically, malting was carried out on a large stone floor at the distillery itself, with the germinating barley turned by hand with wooden shovels. This traditional practice — known as floor malting — has largely been replaced by industrial malting, though a handful of distilleries such as The Balvenie still maintain floor maltings on site.

The malted barley is ground into a coarse flour called grist and mixed with hot water in a large vessel known as the mash tun. This dissolves the sugars from the malt and produces a sweet liquid called wort.

The wort is drawn off and cooled before the next stage, and the spent grain is typically sold as cattle feed to local farmers — a link between whisky and agriculture that has existed for centuries.

The cooled wort is transferred to large vessels called washbacks — traditionally made of Oregon pine or larch, though stainless steel is now widely used — and yeast is added. Over the course of two to three days, the yeast converts the sugars into alcohol, producing a liquid called wash at around eight per cent alcohol by volume.

The character of the yeast and the length of the fermentation contribute significantly to the eventual character of the whisky.

The wash is distilled in copper pot stills — usually twice in Scotland, three times in Ireland. The first distillation, in the wash still, produces a low-strength spirit called low wines at around twenty per cent alcohol by volume. The second, in the spirit still, produces the new-make spirit at around seventy per cent.

During the second distillation, the stillman makes the cut: separating the volatile foreshots and the heavier feints from the middle portion — the hearts — which alone is collected for maturation. The cut is one of the defining skills of the distiller.

The new-make spirit is filled into oak casks for maturation. Under Scotch Whisky Regulations, the whisky must be matured in Scotland in oak casks for a minimum of three years. In practice, most whiskies are aged for considerably longer.

The cask is not a container but a participant. It contributes colour, flavour and softness through the slow interaction of spirit and wood, and each year a small proportion of the contents evaporates through the porous oak — the angel's share, typically around two per cent per year in a Scottish warehouse.

For a blended Scotch, the master blender selects mature whiskies from many distilleries — typically forty or more — and combines them to a consistent house style. The proportions are determined by nose rather than by taste, using tulip-shaped nosing glasses, and are guarded closely.

Once combined, the blend is often returned to cask to marry for a further period before bottling.

The mature whisky is reduced with soft water to bottling strength — typically forty per cent alcohol by volume for standard expressions, higher for cask-strength releases. It is then filtered, filled, labelled, sealed and packaged.

Some producers omit the chill-filtration step, preferring to retain the natural oils that would otherwise be removed. Others bottle at cask strength without dilution.