Scotch Whisky

Why malt whisky?

Malt whisky is made from barley, yeast and water only, in contrast to blended whisky, which can contain parts of grain or corn whisky. Many factors contribute to the specific taste of malt whisky - way of production, type of barley used, way of drying the barley, water, type of cask, warehousing and similar. Owing to this unique combination, Scotland produces so much different whisky that researching and searching the best one is a long-time and often a never-ending task. According to the current regulations (Scotch Whisky Regulations 2009), there are five legally defined regions of Scotch whisky. These are: Highland, Lowland, Speyside, Campbeltown and Islay. All islands except Islay are officially part of the Highland region, some authors nonetheless use a separate region called Island. Approximately one half of about 100 Scottish malt distilleries is located in Speyside, which is why it is treated separately, despite being part of the geographic Highlands. Islay currently has eight operating distilleries, Campbeltown three, Lowland five, with the rest scattered in the Highlands.

It was long taken that the basic precondition for a certain whisky is the distillery's location. Generally, basic characteristics can be assumed from its place of origin, but, as will be stated later, exceptions do exist. Islay whisky is known for its smoky and earthy aroma, thanks to widespread use of easily accessible peat used to dry the barley. Exceptions to this are certain editions of Bowmore, Bunnahabhain and Bruichladdich. Lowland whiskies are traditionally light and delicate ("Lowland Ladies"), Speyside whisky has a tradition of light fruity and floral aromas. Owing to geographical size, Highland whiskies are very diverse, but generally will have a stronger, especially fruity taste. However, it has to be borne in mind that these are only general descriptions, which need not apply for a particular distillery.

Whisky-making process

The making of whisky requires plenty of water, used for making, cooling and diluting of the new make spirit. As such, a distillery must be located near an abundant source of water. Water, minerals, acidity and water hardness were long taken to influence the taste of whisky.

Germinating barley at Springbank
Photo: Marek Kralovič

Drying of germinated barley at Balvenie
Photo: Marian Kralovič

Malt – formerly, distilleries prepared their own barley on-site, now most of them buy the ground and ready malt from a malting. Only the following still have on-site maltings: Highland Park, Springbank, Laphroaig, Bowmore, Kilchoman and Balvenie - only six of app. 100 Scottish malt distilleries. First, the barley is soaked and let to germinate to create starches. To prevent mildew, it has to be turned over regularly, either by hand or using a machine. Then the barley is dried: some distilleries use hot air, others smoke from burning coal, and yet in others in smoke from mouldering and mainly very smoking peat, which is the case of the whisky's smoky aroma.

After drying, the germinated barley is milled in a large mill into grist, which consists of grit, husk and flour. Before milling it is important to filter out unwanted matter such as pebbles, which might cause an explosion by friction. For the best attributes, distilleries try to keep the ratio of individual parts of ground barley at roughly 70:20:10.



Ground barley at Deanston
Photo: Marek Kralovič

Mash tun made of cast iron at Springbank
Photo: Marian Kralovič

The ground barley is mixed with hot water in a large vessel called mash tun. These vessels are made from cast iron, stainless steel or wood. The mash is then mixed, while starches change into sugars. Hot water is injected usually three, more rarely four times at approximately 64, 76 and 88 degrees Celsius to extract the sugars. The last batch has too little of sugars to be used, so it is recycled and used as the first water of the next batch. The newly-created liquid is called wort.



Washback at Arran
Photo: Marian Kralovič

Washback is a vessel where the wort is mixed with distiller's yeast and ferments.
Traditionally it was made of wood, but many distilleries now use stainless steel, which is easier to maintain. It is asserted that this does not affect the final taste of the whisky, although some admit that bacteria remain in the wood even after the cleaning, which support secondary fermentation.  .
What does affect the final taste is the length of fermentation, which takes two to four days. The end product is wash, a liquid containing about 7 to 8% alc. vol., which looks and tastes similar to beer.


Wash still and spirit still at Edradour
Photo: Marek Kralovič

The three stills at Auchentoshan
Photo: Marian Kralovič

Scotch whisky is distilled twice, more rarely thrice (e. g. Auchentoshan). Most distilleries have the stills in pairs. First destillation occurs in wash still (usually marked red), second destillation in the spirit still (usually marked blue).
Ordinarily, stills are approximately onion-shaped, but differ size and height. All, however, must be made of copper, since the copper acts as a cleanser which catches unwanted parts of sulphur. Longer necks of the stills yield a cleaner and lighter alcohol.

A byproduct of whisky making is draff, which is created especially after mashing and distilling. It is not wasted: this residue is combined, granulated and sold to local farmers as cattle feed.


Condenser at Talisker
Photo: Marek Kralovič

The stills are connected to a condenser, in which the created vapours are cooled and the alcohol condenses into liquid. Usually it is a spiralling copper pipe, which is kept in an open vessel containing cold water. 

Spirit safe

Spirit safe at Bruichladdich
Photo: Marek Kralovič

Flowing spirit in the spirit safe at Bunnahabhain
Photo: Marian Kralovič

Through this locked vessel, all the spirit from wash and spirit stills flows through. The first distillation yields spirit with a content of app. 20.0% ABV, which is redistilled. After second distillation, experience of the stillman comes into play, since the spirit has to be divided into three parts. The first part is called head or foreshots, which is too strong and contains poisonous methanol, and as such it is separated. The second part, called heart or middle cut, is what will become whisky – the exact range differs among distilleries but usually starts at about 70-72% ABV and ends at 60-62% ABV. The third part, called tail or feints, is too weak to be used and is combined with the head to be redistilled in the next batch.



The cask, in which the whisky mature, has an app. 60% influence on the final taste. Legally, a Scotch whisky must mature in an oak cask, usually American white oak or European oak. The kind of wood affects aroma and taste.
Casks are always second-hand, and contain previously bourbon or sherry, in some cases wine or rum.

Cross-section of American oak at Bowmore
Photo: Marian Kralovič

Casks come in different sizes: barrel (180 litres), hogshead (250 litres), butt (500 litres), puncheon (500 litres). More rarely, one can find a quarter cask (110 litres). Smaller casks lead to quicker maturation.
The casks are filled at 63.5% ABV, since this is said to be the optimum strength for maturing. In total, they are used three to four times, then they are exhausted (too weak to give flavour) and the wood is recycled, for example for flower pots.

Casks at Glengoyne
Photo: Marian Kralovič

Cask sizes at Speyside Cooperage
Photo : Marek Kralovič


Warehouse with metal racks at Edradour
Photo: Marian Kralovič

Warehouses can have different layouts. They can be damp, cave-like spaces, where casks are stacked three-high on top of each other, lying on their sides. Another possibility is to build drier brick or metal buildings equipped with metal racks. The most modern way is a pallet warehouse, where the casks are stored six-high on pallets, standing on their tops.

Traditional dunnage warehouse at Arran
Photo: Marek Kralovič

Pallet warehouse at Arran
Photo: Marian Kralovič

During the maturation, app. two per cent of volume and half per cent of ABV evaporate every year. This is called the angel's share, since the distillers previously believed angels were "helping" themselves to maturing whisky. At Arran, the same thing is called the eagle's share, owing to the presence of these majestic predators in the area. Scotch whisky can be called such only if it is made and matured in Scotland, and only after three years have passed since the casks were filled.  Before bottling, the spirit is usually diluted to 40% or 43% ABV. Some whisky is diluted to a higher strength, e. g. 50% ABV., or is not diluted at all. If that's the case, the whisky is called cask strength whisky. If the whisky is bottled from a particular cask, it is called single cask whisky. Once the whisky is bottled, maturation stops.

In Scotland, the following types or whisky are defined:
Single malt – malt whisky distilled in one distillery
Blended malt – whisky made from malt whiskies of different distilleries
Single grain – grain whisky distilled in one distillery
Blended grain – whisky made from grain whiskies of different distilleries
Single blend – whisky made from malt and grain whisky of one distillery
Blended whisky – whisky made from malt and grain whiskies of different distilleries

The formerly used names pure malt and vatted malt, standing for a blended malt, are prohibited by the current regulations.


Whisky containing less than 46% ABV is often chill-filtered before bottling. In this process, the whisky is cooled to a temperature between -10 to 4 degrees Celsius and then passes from an adsorption filter, which filters out fatty acids, proteins and esthers. The reason is mostly cosmetic, since these can cause whisky to go cloudy when served cold, with water or ice. However, some consider this to alter the taste. For this reason, some distilleries do not chill-filter whisky before bottling – in this case, "non chill-flitered" will be stated on the laber. For whiskies bottled at above 46% ABV, chill-filtering is unnecessary, since it does not contain any particles causing cloudiness.


If the label on the bottle states that a single malt is 10 years old, that means that the youngest whisky must be at least 10 years old. Often, older whisky is used from the same type of casks to achieve consistency. Despite this fact, the resulting whisky remains single malt, as no whisky from other distilleries is involved.