Column still (Coffey still)

Robert Stein, at Kilbagie distillery near Alloa, took the first steps towards continuous distillation two years before Coffey, with a single column heated by injected steam. Aeneas Coffey's patent of 1830 used two copper columns, the analyser and the rectifier, with perforated copper plates; the design was simpler, more robust and cheaper to heat, and gave a stronger, purer spirit. Grange was the first Scottish distillery to install a Coffey still, in 1834, and by 1850 eleven more had followed. The company that built Coffey's stills later passed to his foreman John Dore.

Wash flows continuously down through a series of perforated plates in the first column while steam rises from the base, stripping the alcohol and other volatile compounds; the vapour is then refined in a second column. Irish grain whiskey is drawn from the final column at about 94.5% alcohol by volume, and is much less intense in flavour than pot-still spirit. Scotch Whisky must be distilled below 94.8%, so that it keeps an aroma and taste from its raw materials.

Grain whisky distilleries in Scotland always use some malted barley together with other, unmalted cereals; most of their spirit goes into blended Scotch.