Traditional Distillation Techniques

At the heart of whisky-making is the still. Distillation is the process by which a fermented wash — essentially a form of unhopped beer at around eight per cent alcohol by volume — is heated so that the alcohol vaporises and is then condensed back into liquid at a higher strength. It is a process practised for centuries, and the equipment used to perform it has changed remarkably little.

Two forms of still dominate the industry. The pot still, in its traditional copper form, is a batch device: filled with wash, heated, run off, cleaned and refilled for the next distillation. It is the still used for all Scotch malt whisky, for Irish pot still whiskey and for most premium whiskies globally. The column still, patented by Aeneas Coffey in 1831, is a continuous device: wash enters at the top, spirit is drawn off from perforated plates below, and the process runs uninterrupted. Column stills produce lighter spirits at greater volume and are used for grain whiskies, bourbons and many other categories.

The choice of still shape matters enormously. Tall, narrow-necked pot stills favour reflux — the condensation of heavier vapours back down into the pot — and produce lighter, cleaner spirits. Short, squat stills allow more of the heavier compounds through and produce oilier, more robust whiskies. The stills at Glenmorangie are among the tallest in Scotland; those at Lagavulin among the shortest. It is one of the reasons the whiskies of the two distilleries taste so unlike one another.

Tall stills give lightness. Short stills give weight. The shape is the signature.

During distillation, the stillman must make what is called 'the cut'. The first vapours to condense — the foreshots — contain volatile compounds that are harsh and undesirable. The last — the feints — contain heavier oils that would coarsen the whisky. Only the middle portion, the hearts, is collected for maturation. Determining precisely when to make each cut is one of the defining skills of the distiller, and traditionally it was done by taste, by smell and by observation of the spirit safe.

Copper itself is part of the story. Copper reacts with the sulphurous compounds produced in fermentation and removes them from the spirit, contributing to the smoother character of pot-still whisky. It is why every serious whisky pot still in the world is made of copper, and why the metal is replaced periodically as it slowly erodes.

The role of the master distiller — historically a hereditary craft, often passed through generations of the same family — is to hold all of these variables in balance, day after day, so that the spirit that leaves the still on Tuesday tastes as it should taste on Wednesday, and next year, and the year after.