How is whisky made?

3. Illustration of the whisky making process

The barley is at the base of all the process. The quality of the barley has a great influence on the quality of the end product.
The barley being used for the production of whisky is carefully selected. It is after all the basic ingredient which will determine the quality of the whisky which will be sold years later. This selection was traditionally the job of the manager of the distillery.
Most of the distilleries nowadays buy their malt in a malting plant (for economic reasons), this selection is done less and less by the distillery managers, but well by the persons in charge at the malting plant. However, the maltings must respect precise requirements from the distilleries, in order to let them produce their whisky properly, and on the same way year after year.
There is no legal obligation to use Scottish barley to produce Scotch whisky. Even if some producers would like to go back to the tradition, like Bruichladdich does, most of the distilleries are not concerned by the origin of their barley. The most important thing is the highest sugar content and the lowest price. The combination of those two elements is often the only criteria in the choice of a variety of barley. A great deal of the barley used to produce Scotch whisky is coming from England or South Africa. It is not excluded that GMO are used, but it is difficult to get evidences of that. Anyway, this would perfectly conform with the productivity logic. If genetically modified barley gives better harvests with a better sugar content...

Water is another of the most important ingredients in the making process of whisky.
The quality of the whisky depends on the quality and purity of the water. Water in Scotland is famous for its great purity. The difference in taste between the whisky coming from various distilleries is partly due to the quality of water used.
Water in the Highlands is often peaty, which gives it a brownish colour. Substances, deriving from peat, are carried by the rivers which water is used to make whisky, and contribute often to the original taste of scotch whisky.
But water is certainly not the only determining factor in the taste of a malt whisky. The manufacturing process is of course very important in the final taste of whisky. Water is used in several steps during the distillation process. First of all, it is mixed to the grinded malt in order to produce the wort. It is also used for cooling the alcohol leaving the still. Last but not least, water is used to reduce the alcohol at bottling.

 Yeast (brewer's yeast, often mixed with culture yeast) will start the fermentation process.
The role of yeast is capital. The choice of the yeast is part of manufacturing secret of the distilleries.

The making process of whisky takes at least 3 years. If a grain (malted or not) spirit did not stay for at least 3 years in an oak cask, it does not deserve the name of whisky. Even worse, it does not have legally the right to be marketed under the name of whisky.
To deserve the name of Scotch, the whisky has to stay for this minimum of 3 years on the Scottish ground.
Generally, the whiskies marketed as single malt aged for a minimum of 8 to 10 years.
Whisky, just like any other alcohol, is the result of natural chemical alterations of sugar. To produce alcohol, we first need to produce sugar.
Sugar is potentially present in barley, which grows easily under the Scottish latitudes. Many alcohols are made from grapes, but the climate of Scotland is not suited for this kind of culture. But the manufacturing process remains very similar to the one used in production of alcohol based on other raw material.

Malt is the result of the malting process. The barley is made wet and spread on the malting floor to allow the germination process to start. A succession of chemical reactions change the starch contained in the barley in sugar. Later sugar will change into spirit.
The malting art consist of finding the right moment to stop the germination process: not too late but not too early.
According to the season, malting takes between 8 and 21 days. Constant attention has to be given to the process. Barley has to be turned over regularly to ensure a constant moisture and temperature and to control the germination of the barley grains.
The end of the germination is triggered by drying the germinating barley over a fire (kiln). This oven is often heated by peat. The smoke of the peat fire in the kiln is determining is the taste of many a whisky.

Germination is stopped by drying the grains above an oven (kiln). The kiln on the picture is the one of Laphroaig. A kiln was often fed with peat. It is the smoke of the peat fire which gives some whiskies their particular flavour.
The art of some distilleries is in the correct proportioning of peat used to dry the malt. Springbank for instance produces 3 different malts: Springbank, Longrow and Hazelburn (which will be available from 2006). One of the main differences between those 3 products is the proportion of peat used for drying the malt. There are also some other differences in the distillation process in the case of Springbank. Bruichladdich also produces 3 different whiskies with different peat levels: Bruichladdich, Port Charlotte and Octomore (the two latter's are recent productions, and will not be marketed before several years).
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Maltings

Economic reasons obliged most of the distilleries to abandon their malting floors during the 1960's Malting happens mainly at specialized plants, called maltings. This maltings produce malt according to the requirements of their clients. The same malting company produces thus several kinds of malt. There are however notable exceptions to that rule: Balvenie, Laphroaig, Highland Park, Bowmore are some of the distilleries which produce parts of their own malts. According to some sources, these distillery would produce about 30% of their needs. Springbank produces 100% of their malt.

Maltings can be independent, or belong to big concerns, owning their own distilleries, like Diageo. Diageo, who owns a great deal of the Scottish distilleries (see distillery owners) has created its own malting plants, to supply the distilleries of the group (like for instance the malting at Glen Ord) or for local distilleries, like the Port Ellen Maltings on Islay.

 

 

The latter is the result of an agreement signed by all the Islay distilleries who oblige themselves to buy a certain amount of malt at the Port Ellen Maltings. This malting plant is in full expansion, just like the distilleries of the island, and is progressively occupying the territory of the (henceforth former) distillery of Port Ellen.
The maltings do not have the romantic aspect of (old) distilleries, with their pagoda roofs...

 

When the malt is dry, it is grinded to make a kind of coarse flour which will be used in the next operations.

This flour is called grist.

Malt grinding is done with a malt mill in the distillery itself.

Nearly all the distilleries use the same kind of mill, traditionally made in England, in Leeds, which is sometimes hard to accept for a real Scot.

The grist will be mixed with hot water in the mash tun. Generally one volume of grist is mixed up with 4 volumes of water. In this operation, 3 successive waters are used, at a temperature between 63 and 95%

A mash tun can contain up to 25000 litres and has a double bottom with thin perforations to let the wort (sugared liquid resulting of the brewing operation) flow out, retaining bigger parts which will be sold as cattle food. In order to facilitate the process, mash tun have rotating blades. The waste is called draff.

 

The first operation, taking about 1 hour, will change the starch in fermenting sugars. The mix of water and grist looks like a kind of traditional porridge.
This sugared juice is called wort. The remainders will be brewed 3 to 4 times, in order to get a maximum of wort.

The quality of the wort is controlled by the excise men, because it determines the amount of spirit which will finally be produced. This is the base of the taxation of the distillery. .

The action of the yeast on the sugar of the wort will produce alcohol and carbon dioxide. The wort starts bubbling, which will sometimes result in strong vibrations of the wash back, despite its impressive size. Traditional wash backs are made of Oregon pinewood or scottish larch. However, more and more stainless steel wash backs are used nowadays, because they are easier to maintain.

 

The result of the fermentation is the same in both kinds of wash backs. However, lots of distilleries pretend Oregon wood is much better, and even hi-tech distilleries like Caol Ila do not believe in stainless steel wash backs

The picture above has been taken at the Glenkinchie distillery, while the stainless steel wash backs on the left belong to Laphroaig.

 

 

 

The wash

As result of the fermentation of the wort, a kind of beer with a percentage of approximately 8%. Till now, there are no substantial differences in the process of making whisky, and the making of beer.

From now the difference between the process will become obvious. Beer will be perfumed with hops, while whisky will be distilled without alterations.

The distillation is the process used to separate alcohol from water and other substances contained in the wash. This is a classical operation, and it is the base of each spirit round the world. It is used in perfumery too. Distillation is made in stills. The principle is very easy: water evaporates at 100% while alcohol does from 80%. Alcohol will thus be transformed in vapour and raises into the still before water itself begins evaporating.

Pot stills are used in Scotland.

The size of the stills is fixed by the law. This is due to historical reasons, related to excise rights.

Edradour has the smallest legal stills of Scotland. If the stills were a bit smaller, the distillery would lose its licence.

Stills are in copper, because this material has a great influence on the physical process of separation of the waters and the spirits. The quality of the dram we will enjoy a few years later depends partially on the copper surface being in contact with the liquids during the distillation process. Other things are important, like the shape, the height, the length of the lyne arm are also very important in the making of the taste of the future whisky. If a distillery has to add or replace a still, it will always try to get a still with the same capacity and the same shape, in order to guarantee a constant quality to the whisky.

Because of the extreme diversity of the stills used throughout Scotland, it is not possible to display some pictures on this page. I created a special page with pictures of various stills from several Scottish distilleries. To get there, just click on the still icon on the left. By the way, this is a still of Glenfarclas distillery.

Traditionally, the stills were heated with coal or peat, depending on the areas and possibilities. Currently, nearly all of them are heated with vapour, because this method gives more control on the process.

The fuel used to heat the vapour is generally petrol, but it can happen that coal is still used.

The huge quantity of heat produced by distilleries is sometimes recycled. For instance, the municipal swimming pool of Bowmore is warmed with recuperation heat from the distillery.

Scotch whisky is double distilled, with some exceptions to this rule, like Auchentoshan which is distilled three times, just like Irish whiskey.

The distillation process occurs in two stages in two still with different capacity and shape.

The first distillation occurs in the wash still whose capacity can be between 25 and 30.000 litres and transforms the wash in "low wine", at about 21 % of alcohol. If the stills were originally heated with a naked fire, generally from coal or gas, the current stills are heated by a serpentine within the still, where the vapour is circulating.

The alcohol vapours are cooled outside the still by condensers. The traditional condensers were serpentines immerged in a great open wooden back, containing cold water.
Currently, most of the distilleries use vertical tubular condensers, because the output is better. Waste of the first distillation is called "pot ale" or "burnt ale", and is transformed to feed cattle too.
The low wines resulting from this first distillation are kept in the "low wine receiver and will be used as ground for the second distillation.

The second distillation occurs in a spirit still which is generally smaller than the wash still, as there is less liquid to process.

 

During the second distillation, only the "distillation heart", the part which has between 63 and 72% of alcohol will be casked. The heads and tails, also called feints, will go to the feint receiver, and reused mixed with the low wines of the next distillation.
To separate the feints from the distillation heart, a spirit safe is used. This spirit safe (was) used for the determination of the quantity of alcohol produced , to calculate the taxes due by the distillery

The distillation process is unique for each distillery using pot stills. (Distilleries using Lomond stills - there are very few of them left now - can produce several types of whisky.)
This means that all the whiskies produced by a certain distillery are treated on the same way, with the same malt, the same stills on the same way by the same people... So, why can they be so different from each other? The answer to this question is in the aging process, the casks used, the nature of the warehouse, the taste of the air (it seems that a whisky aged in casks stored in warehouses close to the sea have a different taste from a whisky aged on some other place). Glenmorangie Cellar 13 is a good example of that phenomenon.

 

If the surrounding air has a (little) influence on the taste of whisky, one must realize that many distilleries bring their casks to some central place near Edinburgh for their aging. It it not clear to me if the whiskies aged that way are marketed as single malt or if they will be used in blends.
In other words, the influence of the air on the taste of whisky; myth or reality?
There is one thing for sure however, and that is that the role of quality of the barley, the making process, and the nature and quality of the casks where it was aged is very important. According to some specialists, this could be good for 95% of the final quality of a malt whisky.

To have the right to bear the name of whisky, a grain spirit (malted or not) must be aged at least for 3 years in a oak cask. Unlike Cognac which is stored in new casks, the Scottish always use second hand casks.
 

The kinds of casks

The oak casks are classified by capacity, and the following casks exist:
A gallon is 4.546 litres The capacity of the casks is approximated.

PIN	4,5 gallons
FIRKIN	9 gallons
KILDERKIN	16 gallons
BARREL	36 gallons
HOGSHEAD	54 gallons
PUNCHEON	72 gallons
BUTT	108 gallons

The information about the capacities of the various casks comes from the Campbeltown museum.


The picture has been taken in the yard of Old Pulteney. Casks on the foreground are "sherry butts"

The Scotch whisky industry uses mainly 3 kinds of casks:

the "barrel" : ±190 litres
the "hogshead" :± 250 litres
the"butt" : ± 500 litres

The shape of the casks is mainly due to historic reasons, related to storage problems on ships. Sherry was carried on Spanish gallions, and the slender shape of the butts was the best for storing on this kind of ships, while the Portuguese Port was stored in a more bulbous cask, which was easier to carry on Portuguese merchant ships.

The "finishes"

Often whisky is aged for a while in bourbon casks, and finishes his aging period in some kind of other cask, in order to give is some new fragrances, before bottling. Generally it stays for 6 to 12 months in another kind of cask. This explains the "wood finish" mention on some bottling's. For instance, the 18 yo Glenmorangie finishes its maturation in next casks, which is rather uncommon in Scotland.

A whisky cask is always a second hand cask. It generally contained bourbon (american whiskey made from corn - (maize). Sherry is also very popular in the whisky industry. Other casks are used too, like Port, Madeira and more rarely Claret (French red wine) or rum, etc... Glenmorangie is specialized in "wood finishes" and some of them are very expensive, probably because of the rarity of the casks.

However, there is a question about this wood finishes. If the aim is to give some new and pleasant fragrances to the whisky, everybody knows (at least in the whisky industry circles) that this method is used sometimes to hide some distillation errors. Often, the casks are warmed up before transferring the whisky, in order to accelerate the fragrance transfer. Such practices are not acceptable, because the consumer has no way to know about this.

Casks industry

A quick mental calculation ca make you feel dizzy. There are about 100 active distilleries all over Scotland. The average production of each of them is between 1.200.000 and 2.000.000 litres a year. To deserve the "Scotch label", whisky must stay at least 3 years on the Scottish territory in oak casks. Assuming that the annual production is about 150.000.000 litres, the absolute minimum of whisky stored in Scotland is 450.000.000 litres This only to guarantee the legal right to be called Scotch whisky. This is without taking in account the huge quantity of whiskies which are aging for 10 to 30 years...On the other hand, the casks used for storing whisky are never new casks. It is thus very important to maintain the casks in good state. Some distilleries have their own cooperages (like Balvenie or Bruichladdich for instance), but most of them prefer outsourcing this to specialized companies. There are lots of cooperages in Scotland, and the most famous of them (because it is a first class tourist attraction) is the Speyside Cooperage, situated half way between the Glenfiddich distillery and the centre of Dufftown. This cooperage has about 300.000 casks in stock. All of them need reconditioning. There are about 20.000.000 cask all over Scotland. A cask can be (re)used for a maximum of about 60 years.

The angels share

The advantage of oak for maturing alcohol is that it is not airtight. It lets surrounding air enter the cask (which explains the salted taste of a whisky aging near the sea), but is also lets evaporate the whisky it contains. It is generally admitted that between 1 en 2% a year evaporates this way. Evaporation can affect water contained in the cask, but also the alcohol itself, resulting in a diminution of the alcohol percentage. That is called "the angels share". However, this percentage is theoretical, because this could result in a strange situation, as old whiskies (30 years and more) would lose their right to be called whisky. Indeed, assuming a whisky has about 70% of alcohol when it leaves the spirit still, and loses about 1% of alcohol a year a 30 years old whisky would just have a percentage of 40%, which is the lowest limit for a whisky.
The angels share is indeed the part of alcohol which escapes to excise rights. Excise rights are calculated on the amount of alcohol coming out of the still (and not on the amount of water). As this amount is diminishing over the years, it would not be fair to tax the marketed whisky based on the alcohol percentage it had when it was distilled...

The nature of the warehouse is also very important. A damp cellar or a dry cellar will influence the evaporation of the spirit differently. In a dry cellar (with a concrete floor), water will evaporate mainly, letting a dryer whisky with a higher alcoholic percentage. In a damp warehouse (beaten-earth floor) the alcohol will evaporate, letting a rounder whisky, with a smoother taste.

Bottling is the last step before putting the whisky on the market.

Unlike wine, whisky does not mature anymore in the bottle. So a 12 years old whisky stays a 12 years old even 12 years later, and does not become a 24 years old one....

When bottling, some residues are left in the whisky. The effect of this is that whisky looks "cloudy", and this is not always appreciated by the consumer. That's why distilleries found out the "chill filtering", which removes all this residues. The problem with chill filtering is that it also removes parts of the fragrances and of the taste.
With the current revival of single malt, more and more bottlers (in dependant or official) bottle their whiskies without chill filtering. And this makes single malt lovers very happy.

During bottling, the alcohol percentage is reduced. This is the other operation where the quality of water has a great influence on the taste of whisky. The minimum percentage of alcohol for whisky is 40%. Most of the bottles are marketed at this percentage, because the excise rights are calculated on the alcohol proportion in the bottle. The excise rights are particularly high in Great Britain, but in other countries they are lower. That's why on the international market, whiskies are frequently bottled at 43%.
For some technical reasons, the ideal percentage for bottling without chill filtering seems to be 46%. Most of the non chill filtered whiskies are marketed at 46%.

Often whisky is not diluted when bottled. That's called cask strength bottling.

Generally, the casks are mixed before bottling, to get a more standardized product, just like great wines. When the whisky comes from just one cask, it is called "single cask".

Most of the distilleries do not bottle their own whiskies, but let this happen at specialized plants. Exceptions among others are Glenfiddich, Springbank, Bruichladdich and Loch Lomond. Even if they do not bottle themselves, the responsibility of the bottling stays from the distillery. This is called "official bottling". This operation happens often in the suburbs of Edinburgh where several bottling plants are installed, belonging to distilleries (like Glenmorangie in Broxburn) or to independent bottlers, like Ian McLeod in the same town.

 

 

Independent bottlers

A very interesting phenomenon in whisky world is the work done by independent bottlers. Unlike bottling plants who work on behalf of distilleries, the independent bottlers buy casks at one or more distilleries, choose the type of cask, and let it mature in own warehouses or in the distillery warehouse. The independent bottler decides when the whisky will be ready for selling. These bottlings are marketed under the name of the bottler, and sometimes the name of the distillery does even not appear on the bottle -rarely-. Some of these companies are Signatory, Ian MacLeod, Douglas Laing (Provenance and Old Malt Cask), Cadenhead, etc. ..

This illustration is based on pictures of the scale model of an distillery displayed at the Glenkinchie distillery. Visiting this distillery is very interesting, especially because of the very nice distillation museum it hosts, and the pictures below represent the master piece of this museum.

Barley reception at the distillery

Malting floors

Kiln (oven) used to dry the malt. This image of the distillery makes the role of the pagoda roofs on (old) distilleries obvious.

After drying the malt, it goes through the malt mill to be transformed in a kind of coarse flour (like muesli)

After grinding, the malt is transferred in the mash tuns where it is mixed with hot water in order to extract the sugar.

The wort is then transferred in the wash backs , where yeast is added, to start the fermentation.

The fermented liquid is then distilled in the stills

The distilled alcohol is cooled in a condenser .

before being transferred in oak casks for a minimum of 3 years.