The origins of malt whisky distilling in Scotland are lost in the mists of antiquity. They date back at least to the monks of the 15′” century and probably long before.
Best quality barley is first steeped in water and then spread out on malting floors to germinate. It is turned regularly to prevent the build up of heat. Traditionally, this was done by tossing the barley into the air with wooden shovels in a malt barn adjacent to the kiln.
The dried malt is ground into a coarse flour or grist, which is mixed with hot water in the mash tun. The water is added in 3 stages and gets hotter at each stage, starting around 67°C and rising to almost boiling point.
The wort is cooled to 20°C and pumped into washbacks, where yeast is added and fermentation begins. The living yeast feeds on the sugars, producing alcohol and small quantities of other compounds known as congeners, which contribute to the flavour of the whisky. Carbon dioxide is also produced and the wash froths violently. Revolving switchers cut the head to prevent it overflowing. After about 2 days the fermentation dies down and the wash contains 6-8% alcohol by volume.
In some mysterious way the shape of the pot still affects the character of the individual malt whisky, and each distillery keeps its stills exactly the same over the years.
The wash is distilled twice – first in the wash still, to separate the alcohol from the water, yeast and residue called pot ale – the solids of which are also saved for use in animal feeds.
All the distillates pass through the spirit safe – whose locks were traditionally controlled by the Customs & Excise. The stillman uses all his years of experience to test and judge the various distillates without being able to come into physical contact with the spirit.