Malt whisky is made from just three ingredients… Barley, Yeast and Water. The technique used today has undergone some modernisation but is largely the same process developed centuries ago.
First, the barley is steeped in water and spread on a malting floor. These conditions essentially fool the barley into thinking it is spring and time to grow. To do this, it must access its reserves of starch – this is what a distiller needs to make alcohol. The floor is ‘turned’ several times a day to regulate temperature and prevent build up of mould. After a few days the barley is collected and dried in a kiln, halting growth and preserving the starch. Drying is achieved by the application of hot air or sometimes by peat fire – this is where smokey whisky gets it’s character.
The dried barley is ground into a grist and then mashed (mixed with hot water). The starch in the barley will convert to sugar and run off as a syrupy liquid known as wort.
The wort is transferred to large vats (or washbacks), made from wood or stainless steel. Yeast is added and then left to ferment for a number of days. In essence this process creates a wheat beer of around 9 or 10%. This is otherwise known as the wash.
The wash is fed into copper Pot Stills (which are essentially big kettles) and heated. As the temperature rises, the alcohol content will evaporate faster than the water and rise as vapour. This vapour travels up the Swan Neck of the still and along a pipe known as the Lyne Arm before passing through a condenser which cools and returns it to liquid form.
After one distillation the 9% wash has been converted into Low Wines of around 20%. The process is then repeated, only this time the Low Wines are fed into the Still. This second run creates a clear spirit known as New Make, of around 70% ABV. The spirit output of a still is divided into three sections – head, heart and tail. Only the heart is transferred to casks while the head and tail are sent to be re-distilled with the next batch of wash.
The New Make spirit will be put to sleep in Oak casks for a minimum of 3 years – anything less and it can’t be called whisky. Anything from 60 to 80% of a whiskies flavour can come from the wood it was matured in. The spirit soaks into the Oak and draws out flavour and colour. The casks influence can depend on its size and how many times it has been used before. A new cask will give stronger flavour than an old one for example, and a smaller cask will mature spirit faster than a large one as there is greater contact between the spirit and wood.
The location used to store the cask could also have an effect. Wooden casks breathe, allowing the spirit inside to evaporate (the angel’s share) while also pulling air in at the same time. This is possibly why so many coastal whiskies have a salty, briney note to them.
Blending & Bottling
The master blender will decide when a cask is ready to be bottled. It could either be bottled as a single cask or it could be vatted with other casks in the warehouse to make a larger batch of single malt whisky – so long as any age statement featured on the bottle is that of the youngest cask used in the vatting.
Once the blender is satisfied with their cask selection it’s time for the whisky to be bottled. There are few distilleries that bottle onsite these days, most transport to centralised bottling plants. There are a few exceptions however, Springbank for example, take pride in completing the whole process on site.
Then, finally, the whisky is ready to be shipped and loaded onto shop shelves the world over, waiting patiently for you… or me… to come along and give it a new home… and thats where the fun really begins.