Distillation results in two different residues, which are technically referred to as co-products: pot ale from the first distillation, and spent lees from the second. Both represent significant volumes of liquid, which also play an additional role during the production process, saving a distillery significant amounts of time and money.
The quantity of pot ale remaining in the boil pot (ie. base) of the still is around two-thirds of the charge (ie. liquid being distilled). This means, for example, that a charge of 12,000 litres at Glenmorangie yields 4,000 litres of low wines, and leaves 8,000 litres of pot ale. Meanwhile, at Glenrothes a 12,500 litre charge results in around 7,500 litres of pot ale.
Pot ale resembles a pale yellow, golden liquid, with a malty, burnt cereal and yeast…
