All About Whisky Stills

The type, shape and size of whisky stills are thought to affect taste. What characteristics of still design are so important?

The still plays a vital role in the creation of whisky. Distillers claim that a certain size and shape of a still is responsible for the characteristic taste of a whisky brand. Whilst there are numerous other factors that create a brand’s taste, there’s no doubt that a still affects the end result.

In terms of the production chain of Scotch whisky, there are three phases: fermentation, distillation and maturation.Maturation is the easiest to understand – the alcohol is put in barrels and left to mature. Fermentation is the process of sugars turning in to alcohol, and specifically in whisky production it refers to making an alcohol out of barley and water. The barley is germinated using water and the starch within it turns to sugar. It is then milled and combined with hot water to make a mash. Once even more sugars are released from the mash, yeast is added to turn the sugars in to alcohol. The result is called a wash, which is mildly alcoholic.

whisky distillation

Ben Nevis distillery

This is the point at which distillation comes in. Savvy readers will have observed that the word still is in distillation. Distillation is the process of heating a liquid so that it evaporates, and then having it recondense. This is done to separate the components, as each component of a wash has different points at which it will boil. Distillation takes place in stills, which are made of copper. There are two different stills used in whisky production: wash stills and spirit stills. The wash stills are what the wash goes in to – this creates a more concentrated alcohol called low wines. The low wines is then put through the spirit still to create a highly concentrated alcohol. Part of what comes out of the second still is put away in barrels for maturation.

Why Are Whisky Stills Made of Copper?

There are numerous reasons why copper is the metal of choice for stills.

  • Copper is an excellent conductor of heat, which allows the stills to be heated up more quickly and requiring less energy
  • Copper absorbs sulfur, which can negatively affect the taste of the whisky. The chemicals combine to create copper sulfate, which can be found on the surface of the stills after distillation.
  • Copper prevents the creation of some nasty chemicals during distillation that can be hazardous to health

Some distilleries are turning to using stainless steel stills (try saying that out loud) with a piece of copper inside. This allows the copper to absorb the sulfur while also being a sturdier still – stainless steel is much harder than copper, less prone to warping, easier to clean and cheaper. The whisky industry is nothing if not traditional, though, so many distilleries continue to use stills made completely of copper.

whiskey stills

Glendronach stills

Does the design of whisky stills matter?

The uniqueness of stills, as previously mentioned, lies in their size and shape. It’s impossible to say whether the still dimensions really matter too much. There is a tendency that large, thin stills tend to produce a lighter flavor, and smaller, fat ones tend to produce a more concentrated flavor. This could be a bit of simple chemistry – the more surface area is available for chemical reaction, the more flavors are ‘removed’ from the liquid. One of the most often talked about characteristics of a still is the lyne arm angle. This is the angle at which the arm at the top of the still is positioned at. Upwards produces a lighter taste and downwards produces a fuller taste. This is all about reflux, or having chemicals drip back down in to the still, which in turn changes the flavor profile.

whisky stills

Glenfiddich stills. Note the downward sloping lyne arms.

Stills can be heated in different ways. Traditionally, they are heated from below, but in modern times a heating element can be within the still that heats the liquid. While I think distilleries showing off their stills as part of marketing is a bit silly, there’s decent evidence that still design does make a difference in taste. It’s only one component of a complex process, though.

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