Section 8: Definitions
A single whisky is the product of one particular distillery.
means to convert to sugar. In whisky distilling it refers
to the process which takes place during the malting and
mash-tun stages by which enzymes in the malt, referred
to as diastase, turn the starch in the cereals into sugar
ready for the fermenting action of the yeast.
When conditions of temperature and moisture favour
germination, the embryo and associated par.s of the
barley grain secrete a mixture of enzymes commonly
known as diastase. These act to modify and make soluble
the starch in the barley, thus preparing it for
conversion at a later stage to maltose.
Wort is the liquid drawn off the mash-
tun in which the malted and unmalted cereals have been
mashed with warm water Wort contains all the sugars of
the malt and certain secondary constituents. After
cooling, it is passed to the fermenting vats.
In Malt distilleries the cereals are all malted; in
Grain distilleries a proportion only is malted, the
remainder being unmalted. In some cases, Grain
distilleries do not separate off wort, passing the
complete mash to the fermentation vessels.
The wort or mash technically becomes
wash as soon as yeast is added to start fermentation
However, the term is usually used to refer to the liquid
at the end of the fermentation. It IS the wash which
forms the raw material of the first distillation in the
Pot Still process and of the only distillation in the
Patent Still process
Malt Whisky is distilled twice - although a few distilleries may
undertake a third distillation - in Pot Stills which resemble huge
copper kettles. The spirit is driven off from the fermented
liquid as a vapour and is then condensed back to a liquid.
In the first distillation the fermented liquid, or wash,
is put into the Wash Still. which is heated either directly
by fire or by steam-heated coils. At this stage the wash
contains yeast, crude alcohol, some unfermentable matter
and the by-products of fermentation. During the process
of boiling the wash,
changes take place in its constituents which are vital to
the flavour and character of the whisky.
As the wash boils, vapours pass up the neck of the still
and then pass through a water-cooled condenser or a
worm, a coiled copper pipe of decreasing diameter
enclosed in a water jacket through which cold water
circulates. This condenses the vapours and the resulting
distillate, known as low wines, is collected for re-
distilling. The liquor remaining in the Wash Still is
known as pot ale or burnt ale and is usually treated and
converted into distillers' solubles for animal feed.
The low wines are distilled again in the Spirit Still,
similar in appearance and construction to the Wash Still
but smaller because the bulk of liquid to be dealt with is
less. Three fractions are obtained from the distillation in
the Spirit Still. The first is termed foreshots, the second
constitutes the potable spirit, and the third is called
feints. The foreshots and feints are returned to the
process and redistilled in the Spirit Still with the
succeeding charge of low wines. The residue in the still.
called spent lees, is run to waste.
In the case of the Spirit Still, the design of the still,
the height of the head (or top) of the still and the angle of
the wide-diameter pipe or Lyne arm, connecting the head
to the condensing unit, are all very important and have
an effect on the distillate.
The Pot Still has changed little in general design
over the centuries.
Whisky, Grain Whisky is distilled in a continuous
operation in a Patent Still. This is sometimes known
as the Coffey Still. after Aeneas Coffey, who developed
it in 1831.
Steam is fed into the base of the analyser and hot wash
into the top. As the two meet on the surface of the
perforated plates, the wash boils and a mixture of
alcohol vapours and uncondensed steam rises to the top of
the column. The spent wash runs down and is led off from
The hot vapours enter the rectifier at the base and as
they rise through the chambers they partially condense
on the sections of a long coil through which wash is
flowing. The spirit vapour condenses at the top of the
rectifier and is run off through a water-cooled
condenser to the spirit safe. Once the spirit begins to be
collected it runs continuously until the end of
Because of the rectifying element present in this
process, the distillate is generally lighter in aroma
than most Malt Whiskies. It consequently has a milder
character and requires less time to mature.
The worm and its surrounding
bath of cold running water, or worm-tub, form together
the condenser unit of the Pot Still process of
manufacture. The worm itself is a coiled copper tube of
decreasing diameter attached by the Iyne arm to the head
of the Pot Still and kept continuously cold by running
water. In it the vapours from the still condense. Fed by
the still, it in turn feeds the receiving vessel with the
The worm is being replaced gradually by the more
modern tubular condenser.
This is the name given to the
product of the first distillation in the Pot Still process of
manufacture. It is the distillate derived from the wash
and contains all the alcohol and secondary constituents
and some water. It forms the raw material of the second
distillation, which is carried out in the Spirit Still. The
feints and foreshots are added to the low wines when the
Spirit Still is charged.
Pot ale, alternatively burnt ale. is
the liquor left in the Wash Still after the first
distillation in the Pot Still process, i.e. it is the residue
of the wash after the extraction by distillation of the low
Foreshots is the term applied to
the first fraction of the distillate received during the
distillation of the low wines in the Spirit Still used in the
Pot Still process of manufacture. They form the first raw
runnings of this second distillation and their collection is
terminated by the judgment of the stillman. The following
fraction of the distillate is the potable spirit.
The foreshots are returned to the still, together
with the feints.
Feints is the name given to the third fraction of the
distillate received from the second distillation in the
Pot Still process. They form the undesirable last
runnings of the distillation. As noted above, they are
returned with the foreshots to the Spirit Still when it
is recharged with low wines.
The term is also applied to the first and last
runnings from the Patent Still. in which process they
are returned to the wash for re-distillation.
The feints and foreshots from the last distillation
of the season are kept for adding to the first low wines
of the succeeding season.
Spent lees are the residue in the Spirit Still after the
distillation of the foreshots, potable spirits. and feints.
They are usually treated and run to waste.
Draff is the spent grain left in the mash-tun after the
liquor, wort, has been drawn off. It represents, as a
rule, about 25 per cent of the malt and unmalted
cereals, if any, put into the mash-tun. Draff enjoys a
large market in cattle food.
The liquids and solids remaining after distillation are
not wasted. nor are they allowed to pollute rivers or
coastlines. In recent years the Scotch Whisky
Industry has invested heavily in developing methods
of treating the residue of distillation so that it now
makes an important contribution to the animal
Most distilleries now possess by-products plants
or, in the case of smaller distilleries in remote areas,
send their waste material to the area plants which
process it into dark grains. These are extremely rich
in protein and are sold in pelletised form to farmers
who use them to enrich cattle food.
Grain Whisky distilleries usually recover the carbon
dioxide produced during the fermentation stage. This
has several applications in industry and in the
production of soft drinks.
- Sales Under Bond are sales on which the
Excise Duty has not been paid. The goods are
consigned to a bonded duty-free warehouse.
- Sales Duty Paid are sales on which the Excise
Duty has already been paid.
© SWA 1995