Whisky Basics 3/4 – Production

by Oliver Klimek on July 24, 2009

This is the third part of a series of four articles about the basic properties of whisky. The first part deals with the different types of whisky. The second part is about regional variations. The focus of this article is on the production process and how it influences the final product.


1. How Whisky is Made

I will describe the process of making malt whisky. Other types vary in details, but the general process is the same.

1.1 Malting

Barley is soaked in water and spread on the malting floor. The grains begin to sprout while the starch inside the grain is transformed into sugar. Just before the grain starts to open, the process is stopped by drying the grains with hot air that is produced by a fire underneath the malting floor.

1.2 Mashing

Malted barley is ground and soaked in hot water in a mash tun. Then the water is saved, the barley is soaked again, saved, soaked and saved again, increasing water temperature on every pass. This process leeches virtually all of the sugar from the barley.

1.3 Fermentation

The sugary liquid is cooled down, then yeast is added. The so-called wort is put into wooden wash backs for fermentation. This takes a couple of days. It has to be taken care that no acetic acid bacteria can get into the wort because this would kill the fermentation process. Also the foam that builds on the top is chopped by a kind of propeller. At the end of fermentation, the alcohol contents of the wash is about 8% to 9%.

So far the process is not much different from making beer, with the exception that no hops is added.

1.4 Distillation

The wash is then distilled two or three times in pot stills made from copper. The first distillation in the wash still gives an alcohol content of about 25%, after the second distillation in the spirit still, alcohol content goes up to about 65%. Some distilleries, notably in Ireland and the Scottish Lowlands, distil a third time resulting in an alcohol content of about 75%.

The whisky is then ready to be filled into casks, sometimes after delaying slightly with water to get a fixed alcohol content before starting the maturation.

2. Influences of the production process on the final whisky

2.1 Malting

In malting the barley you basically have two parameters to change the character of the malt: The duration and the kind of fuel you use.

The longer the malt is dried, the darker it gets and the more aromatic substances are formed due to the Maillard reactions that take place during malting. So a darker malt with give a more full-bodied whisky than a light malt.

In industrial maltings, hot air is blown in with a fan. Smaller maltings use a coal fire. Here you have the choice to add peat to the fire. Adding peat results in a heavy smoke that flavours the malt with phenols. Peat is used predominantly in the Island distilleries, most notably on Islay. But also some highland distilleries have begun to experiment with peat, mainly because peaty whisky is very en vogue these days, so they want their share of the cake as well.

Islay distilleries try to challenge each other now by using higher and higher peat levels. The battle right now goes on between Bruichladdich’s Octomore and Ardbeg’s Supernova.

2.2 Distillation

Mashing and fermenting don’t leave much room for experiments, they basically have to be done the way they are done the get optimum results.

But the process of distillation truly is an art of its own. Here you can work wonders but also ruin a whisky.



Glenmorangie Stills

Glenmorangie Stills


It starts with the properties of the stills themselves. Copper is agreed to be the best material. First it is a good heat conductor, and secondly is acts a catalyst for chemical reactions between the aromatic substances that happen during distillation.

The shape of a still is a very important factor in determining how the final whisky will taste. The shape determines how well the aromatic components that are usually heavier will be separated from the alcohol.

In general one can say that the taller and slimmer a still is built, the more the heavier components are retained in the still instead of travelling along with the alcohol to the condenser. This will then result in a smoother and milder whisky like for example at Glenmorangie.


Laphroaig Stills

Laphroaig Stills



A short and sturdy shape is not much of an obstacle to heavier components, so here a more intensive full-bodied whisky is created, like Laphroaig.

Also the shape of the lyne arm that connects the still to the condenser is important for the separation or creation of aromatics. It is rumored that the peppery quality of Talisker is caused by a funny bend in the arm that was once made to circumvent an obstacle. Nobody knows exactly what is happening in there.

The next important factor to look at is the separation of the foreshot and feints from the middle cut that is used for the final whisky. The foreshot consists mainly of the lightweight methanol wich has to be crucially avoided because it is very dangerous to our health. The feints are heavier alcohols like pentanol and terpene that are not very healthy either. If doses are high enough they can cause anything from hangover to blindness.

The separation is done by carefully raising distillation temperature. At low temperatures the foreshot will be distilled. The stillman now has to decide at which temperature to switch from foreshot to middle cut and from middle cut to feints. A small amount of feints is not necessarily a bad thing for taste the final whisky. It is all about deciding when to stop.

Some of the magic involved in distilling whisky is the fact that foreshot and feints are not thrown away but go again into the still to be mixed with the wash. You would expect the amount of foreshot or feints to raise over time, but for some strange reason it stays rather constant. This is a result of the catalytic reactions in the still that still are not fully understood.

As you can see, making whisky is essentially an easy thing but to get it right is a form of art.

The next part of this series will deal with aspects of storage. Read on…

Pictures from flickr by sashafatcat and ifyr.

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