Barley is germinated to convert starches to simple sugars by soaking in water for 2-3 days. It is then drained.
In traditional maltings it is then spread out on the malting floor and turned at frequent intervals to keep at a constant temperature.
After approximately 7 days the barley's new green shoots have reached the required length to indicate that the optimum amount of starch has been converted to sugar and the barley is then transferred to a kiln, identifiable by its distinct pagoda-shaped chimneys, for drying.
It is at this point that peat may be introduced, the phenolic content created is due to how much peat is used in the drying process. The remains of the stalks and rootlets are removed in the dressing machine and the barley is then passed through a mill and the coarsley ground residue is now known as grist.
The brewing is split into two stages, the first is mashing. The grist is mixed with hot water and heated to between 63-68 C. This mixture flows into the mash tun and is stirred by revolving paddles or a rummager for several hours.
The result is something like a soupy porridge, this is filtered and the resulting sweet liquid is called the wort. The mash tun is then filled three more times with increasingly hotter water each time and filtered, this guarantees that all possible sugars are captured. The second and third fill follows the first through to the next stage, where as the wort from the fourth fill become the first fill of the next run. The residue barley, draft, is then used as cattle feed.
The second stage is fermentation. The wort is now chilled down to 22-24 C and pumped into the washbacks, which are traditionally made of oregon pine, though many distilleries now use stainless steel one for ease of cleaning.
Yeast is now added to the liquid, known now as wash, and the very active fermentation process begins. This will last between 48 and 72 hours depending on the distillery. After the right amount of time has passed we now have a beer like product which strength is between 6-8% abv.
Two types of copper still are used in every distillery, wash stills and spirit stills. The wash is pumped into the larger of the two stills, the wash still, and is either heated directly by coal or gas fires or indirectly through the use of steam coils in the bottom of the still.
The vapours rise and pass over the neck of the still and through a condenser, then it goes on to the low wines receiver, the spirit, now known as the low wines, is now at around 20% abv. From here the liquid is pumped into the next still, the spirit still, and the same process is repeated but the spirit coming off this time varies between 40% and 80% abv.
The stillman carefully monitors the spirit being produced by the use of hydrometers and wants to only remove the “heart" of the run for filling into casks.
The first liquid to run off the spirit still and into the spirit safe, the foreshots, contains the higher alcohol and is too pungent.
The end of the run, the feints, contains the weaker alcohol and is also too pungent. Both the foreshots and feints are kept and go through the spirit still again with the low wines of the next run.
The liquid left in the still after all the alcohol has been drawn off is known as the spend lees.
The new made spirit is then pumped into a spirit vat and reduced in alcoholic strength with water to around 63.5% abv. This now filled into oak casks for mauration.
The most common types of oak casks used are American, used previously to mature bourbon, or European, used previously to mature Spanish sherry.
By law all scotch whisky must be matured in oak casks for a minimum of three years.
During the maturation process the volume of the cask will decrease by around 2% per year in evaporation, the evaporating whisky is known as “The Angels Share".