Double distillation is the most common method of producing Scotch single malt whisky. It involves running the spirit through two separate distillations, typically in copper pot stills, to concentrate the alcohol, refine the flavour, and create a spirit that will develop complexity during maturation. This traditional process has been at the heart of Scottish whisky-making for centuries.
The Definition of Double Distillation
Distillation is the process of heating a liquid to separate alcohol from water and other components, then condensing the vapour back into liquid form. In double distillation, the whisky wash is first distilled in a wash still and then in a spirit still. The first distillation produces low wines, while the second produces the new make spirit that will be matured in oak casks.
Most Scottish single malt distilleries use double distillation, though there are exceptions, such as triple distillation in the Lowlands or Ireland.
A Brief History
Double distillation has been the standard for Scotch malt whisky for hundreds of years. The method was refined in Scotland after centuries of trial and error, balancing efficiency with flavour retention. It became the industry norm because it produces a spirit that is both robust enough to carry through long maturation and refined enough to be enjoyable.
The Process in Detail
First Distillation – The fermented wash, typically around 7 to 10% ABV, is heated in the wash still. Alcohol vapours rise, condense, and are collected as low wines at around 20 to 25% ABV. The remaining spent wash is discarded.
Second Distillation – The low wines are transferred to the spirit still for the second run. Here, the distiller separates the foreshots (early run with unwanted compounds), the heart (the desirable middle cut), and the feints (late run with heavier compounds). Only the heart becomes new make spirit, usually around 63 to 70% ABV.
Cask Filling – The new make spirit is diluted to the desired filling strength (commonly 63.5% ABV) and transferred to oak casks for maturation.
Why Double Distillation Is Favoured
The method strikes a balance between efficiency and flavour retention. One distillation would leave too many impurities, while triple distillation produces a lighter style that is not always suited to Scotch’s traditional robust character. Double distillation leaves enough heavier flavour compounds to give body and depth, which maturation in oak can soften and integrate.
Flavour Profile
Double-distilled whisky can be full-bodied, complex, and varied depending on distillery style. Heavier cuts can produce rich, oily spirits, while lighter cuts can create more delicate and fruity notes. The still shape, cut points, and fermentation length all influence the final flavour.
Notable Examples
Lagavulin – A rich, peated Islay malt with depth and smokiness enhanced by double distillation.
Macallan – Known for a full-bodied spirit that works well with sherry cask maturation.
Glenfiddich – Produces a lighter style within the double distillation framework.
Global Comparisons
Many world whiskies, including Japanese and American single malts, use double distillation to emulate traditional Scotch character. Irish whiskey tends to use triple distillation more often, though some also use double distillation for heavier styles.
Frequently Asked Questions
Is double distillation better than triple?
It depends on the desired style. Double distillation retains more body and heavier flavours, while triple distillation produces a lighter, cleaner spirit.
Does double distillation remove all impurities?
No. It removes undesirable elements while keeping some heavier compounds that contribute to flavour and mouthfeel.
Why is copper used in double distillation?
Copper interacts with sulphur compounds, removing undesirable aromas and helping produce a cleaner spirit.
Conclusion
Double distillation is the backbone of Scotch single malt production, creating a spirit with enough character to mature gracefully in oak while still refined enough to be enjoyable. From the smoky intensity of Islay to the fruity elegance of Speyside, double distillation allows each distillery’s style to shine through.