Until the 1820s all whisky was made in pot stills. These are large onion-shaped vessels with graceful swan necks made of copper. They are used to this day to make single malt whiskies in distilleries throughout Scotland. The size and shape of the stills vary from one distillery to another, influencing the charcter of the final product.
The beginning of the process of making pot still malt whisky is much the same as that of making beer. First of all, barley has to be converted into malt. This used to be done on large stone malting floors at the distilleries themselves. Visitors to distilleries will see many traces off such malting. Today most malt is brought in to the distilleries from large mechanized maltings.
In the traditional process, the barley was soaked in water in a "steep" and then transferred to drain to a vessel known as a "couch". It was then laid out on the malting floor to germinate. During germination the starches in the barley are converted into maltose, a sugar. The malster had to be careful to ensure that germination was even throughout the barley on the floor, known as the "piece". This was done by regularly turning the balrey with wooden shovels or shields.
When the malster judged that germination had progressed far enough, the barley, now malt, had to be dried. This was done in a kiln. The kiln is a large chamber divided in the centre by a perforated floor, usually tiles with small holes in them. Beneath the floor is a furnace, traditionally fired with peat. The heat from the furnace is drawn up through the floor by a wide, open chimney, often crowned with the pagoda-like strukture that has become the hallmark of malt whisky distilling. It is still possible to see malt made in this way at some distilleries, notably Bowmore distillery on Islay and Highland Park distillery on Orkney.
When the malt has been dried it is then ready to be made into whisky. It is ground up into a coarse flour, the consistency of oatmeal. Then it is mixed with hot water and pumped into a vessel called a "mash tun". In this vessel the water and the ground malt is thoroughly mixed so that the sugars in the malt will be released into the fluid. The liquid is then drawn off and pumped into large wooden or stainless steel vessels called "washbacks".
The water used to make the mash is always drawn from the distilleriey`s own supply. The water, more than anything else, influences the final quality and aroma of the whisky. For this reason every distillery jealously guards its source of water.
When the washback is full, yeast is then added and fermentation begins. The length of fermentation depends on the temperature, but usually takes about two days. When complete the liquid has become a malt ale and is known as "wash", hence the term "washbacks".
The wash is now distilled in the larger of the two stills in the stillroom. The distillation process continues until no further alcohol is produced. The resulting spirit is known as "low wines" and the still is often labelled "low wines still". The process is then repeated in the next still - the "spirit still". This distillation is much slower and the temperature is carefully controlled. The stillman discards the first part of the distillate, called "foreshots" and the last part known as "feints", because these contain unpleasant higher alcohols. The centre part of the distillation is preserved and this is the whisky we drink. This spirit is colorless and gets its color during maturing in oak barrels.
Since 1915 all Scotch whisky has had to be matured for at least three years. From at least the early eighteenth century it was known that whisky, when kept for many years in barrels that had previously contained sweet wines, like sherry, became smoother and more delicious to drink. Towards the end of the nineteenth century more and more whisky was matured for between eight and twenty years. Each whisky reaches its maturity at different ages.
