Malt Whisky is
made from three ingredients; barley, water and yeast.
The following section describes the basic traditional
process of making whisky.
malting process begins as the barley is soaked in water
for two-three days in steep tanks. The soaking increases
the moisture content of the grains which in turn
triggers the germination process. The barley is then
moved to a malting facility (e.g. a malting floor or a
drum malting) where the germination continues. The
purpose of the malting is to convert the starch in the
grains into fermentable sugars which will feed the yeast
during the fermentation stage. Heat is produced during
the germination so it is important to turn the barley
continuously to keep the temperature even. If the
temperature rises above 22°C the grains will die and the
process of converting the starch into sugar will be
halted. In a traditional malting floor the barley is
turned by hand with wooden shovels called ‘shiels’.
After the germination is completed it is necessary to
prevent the grain from developing further, thereby using
up its food supply (the fermentable sugars). This is
accomplished in a kiln where the malt is dried to remove
enough moisture from each grain so that further growth
A kiln is a two-storey building where the upper floor is
perforated to allow hot air to pass through from below.
The lower floor contains a furnace where bricks of peat
are burned to generate heat and smoke. The heat and
smoke rise through the perforations and dry the green
malt. It is during this stage that the malt gains its
The kiln with its pagoda roof is the most apparent
characteristic of a traditional whisky distillery. The
roofs are designed to draw the smoke upwards quickly
enough so that the malt is not damaged by the heat (the
temperature of the malt must be kept under 70°C).
Today the majority of distilleries buy all or most of
their malt from centralised commercial maltings such as
Port Ellen and Montrose. For example, Glenfiddich buy
all their malt whereas Laphroaig malt 30 percent of
their barley themselves. Balvenie is an example of a
distillery which still do all their malting themselves.
The malt is ground to grist in a mill and is then fed
into mash tuns together with water that holds a
temperature of about 60°C. The water is changed three or
four times during the eight-hour mashing period and the
temperature is increased each time. The mashing creates
a sugar solution that is called the wort which is then
separated from the spent grains. The mass of used grains
is called the ‘draff’ and is not used further in the
production process but is commonly used for cattle feed.
The finished wort is quite warm and must be cooled
before it can be mixed with the yeast. This is done in
the ‘washbacks’. These containers are traditionally made
from larch or pinewood but today stainless steel
washbacks are also common. Nothing definite can be said
as to what effect the use of either material has for the
finished product. The size of a washback varies from 6
000 to 45 000 litres. Each washback is never filled to
the top since the wort froths significantly during the
fermentation, a reaction caused by the release of carbon
dioxide. After two to three days the yeast is finally
killed by the alcohol it has produced and the
fermentation process is finished. The resulting liquid
has an alcohol content of 5-8 percent and is called the
The copper pot
stills in which the wash is distilled have become the
ultimate symbol of whisky distilleries. The stills are
made from copper since it is a material that is easy to
work with, it does not rust and it is an efficient heat
conductor. The copper is worn down slightly during each
distillation however and the thickness must be
controlled regularly. The minute copper particles that
are released from the still during each run add up over
time and a still seldom lasts for more than 25 years.
The shape of the stills is very important to the
characteristics of the final spirit since it determines
how much of the various substances that are allowed to
pass through during distillation. Therefore great care
is taken to make an exact copy any time a replacement is
In general malt whisky is distilled twice although some
distilleries practice triple distillation, for example
Irish distilleries and a few Scottish distilleries. The
stills used for the first distillation is called ‘wash
stills’. The resulting ‘low wines’ spirit has an alcohol
content of 20-26 percent. The low wines spirit is
distilled a second time in ‘spirit stills’.
The ‘stillman’ has the critical task to collect only the
desired spirits from the second distillation (the
‘spirit run’). A mistake will likely not be discovered
until after the whisky has been stored for several years.
At his assistance is the ‘spirit safe’ which was
developed in the 1820s to allow the government to
control the amount of whisky produced at each
distillery. The spirit safe is fitted with hydrometers
and thermometers which the stillman uses to determine
when the alcohol that exits the still is the correct one
for making whisky. Before the desired spirit starts to
come through however, the stillman has to avoid the
first light alcohols that are called the ‘foreshots’.
These are allowed to flow into a separate tank and will
later be re-distilled together with the next batch of
The desired spirit is called ‘the middle cut’ or ‘the
heart of the run’ and starts to come through as the
alcohol content reaches about 75 percent. The heart of
the run is the only part of the distillate that will
become whisky. The stillman now diverts the spirit into
a separate container. This is called ‘cutting on spirit’.
How long the heart of the run continues to flow varies
from distillery to distillery but on average the
stillman cuts off spirit when the alcohol content of the
distillate is down to a little more than 60 percent. The
following, more heavy, alcohols are called the ‘feints’
ore the ‘tail’ and are diverted to the same container as
When the spirit is cut on and off varies between
distilleries, for example Glengoyne and Aberlour cuts on
spirit early at 73 and 71 percent respectively. Some of
the heavier more medicinal whiskies such as Laphroaig,
Ardbeg and Caol Ila cut off spirit as late as at about
60 percent. Together with the shape of the stills, these
differences are among the most important reason behind
the different characteristics of these whiskies.
Filling and maturation
After the distillation the spirit is cut to the strength
it will have when it is filled into the casks. Most
distilleries cut their spirit to 63.5 percent as it is
commonly believed that whisky matures best at this
specific alcohol content.
All casks used to store whisky are made from oak. Most
distilleries use oak casks that have contained sherry or
bourbon (Macallan is the only distillery to exclusively
use sherry casks). Whisky receives its natural amber
colour from interacting with the wood, although it has
become increasingly common to artificially add colour by
using the E150 additive.
spirit is not legally considered to be whisky until it
has been stored in wood for at least three years. Some
of the whisky evaporates through the wood during storage.
About 1-2 percent of the whisky evaporates each year in
a natural process which is called the ‘angel’s share’.
Since the alcohol content must be at least 40 percent in
order for whisky to be called whisky, this means that
there is a theoretical limit to how many years a whisky
can be stored before it has to be bottled. For example,
if a whisky looses 1.5 percent of its alcohol content
each year it may only be stored for 32 years before the
alcohol content drops below 40 percent. Because of this
it is unusual for whisky to be stored much longer than
30 years. Yet another reason for the limited maturation
period is that whisky constantly picks up tannin from
the wood, and too much tannin ruins the whisky. The
greater part of all single malt whisky is stored between
8 and 12 years.
Before the whisky is bottled it is usually filled into
large tanks to be cut with de-mineralised water to 40,
43 or 46 percent. Some bottlings are filled straight
from the cask however, and are thus called ‘cask
strength’ or ‘raw cask’. This whisky is best enjoyed
with some water although most whisky will in fact
benefit from a slight measure of water since it enhances
both the flavour and the aroma of the whisky.
After the whisky is cut it is common to chill-filter it.
This is done in order to remove slight impurities from
the whisky which otherwise would cause a clouding effect
at low temperatures. Not all distilleries practise
chill-filtering since they believe that it removes some
of the character of the stored whisky.
Most distilleries do not have their own bottling
facilities and buy the service instead from specialised
bottling plants. There are a few, however, such as
Springbank, Glenfiddich and Bruichladdich who still do
their own bottling on site –these also use the same
spring water that is used during the production process
when they make the final cut of the whisky.
Not all matured whisky are bottled and sold as official
bottlings; it is for example possible for a private
individual to buy their own cask at many distilleries.
It is even more common for distilleries to sell some of
their casks to independent bottling companies. Some of
the larger independent bottlers are Signatory, Murray &
McDavid, Cadenhead’s, Gordon and Macphail and Douglas
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