How Whisky Is Distilled
Malt wash is similar in aroma and taste to unhopped beer, according to the Scotch Whisky Technical File. This fermented liquid is the starting point for distillation: partial evaporation followed by cooling the vapour back into liquid concentrates its alcohol and selects its flavour compounds.[1]
Fermentation has already made the alcohol. The still separates and concentrates it, helping shape the character of the spirit that will eventually go into casks.[1][2][3]
From fermented wash to spirit
Wash is the alcoholic liquid that feeds the still. The Scotch Whisky Association explains that wort technically becomes wash when yeast is added, although distillers usually use the word for the liquid at the end of fermentation.[1][6]
HMRC’s archived Spirits Production Manual gives a general wash strength of 6 to 8% ABV. Fermentation produces that alcohol; evaporation and condensation then allow the still to separate the liquid’s components.[2][3]
The key is volatility. HMRC gives ethanol’s boiling point as about 78 °C, lower than water’s, and the condensed vapour contains the more volatile components, including alcohol. But flavour travels too. The Scotch Whisky Technical File records that some volatile substances also interact during distillation to form new congeners, the compounds accompanying the alcohol that contribute to spirit character.[1][3]
Two principal approaches run through whisky production: batch distillation in pot stills and continuous distillation in columns. Scotch production uses both. The Scotch Whisky Technical File describes most North American whiskey production as using a column still process. Each offers a different way to control separation, rather than a choice between flavourful whisky and flavourless spirit.[1][3]
How whisky is distilled in pot stills
Malt Scotch whisky is usually distilled twice, first in a larger wash still, then in a smaller spirit still, also called a low wines still. The first stage produces an intermediate spirit; the second selects the spirit for maturation.[1]
In the wash still, heat sends vapour rising through the neck and over the head towards a condenser. Cooling turns it back into liquid: low wines, the product of the first distillation. HMRC gives a typical low wines strength of around 25% ABV in its archived manual.[1][4]
What remains in the wash still is pot ale or burnt ale. The SWA’s 1995 account describes its usual conversion into distillers’ solubles for animal feed, rather than transfer to the next still.[6]
The second distillation brings the low wines together with foreshots and feints retained from the previous spirit run. As the spirit flows, the distiller separates it into portions. The middle portion goes forward for maturation; the earlier and later portions return for redistillation.[1][4][6]
| Stage | What happens | Published strength or basis |
|---|---|---|
| Fermented wash | Alcoholic liquid enters the process | 6 to 8% ABV, HMRC’s general description.[2] |
| First distillation | Wash still produces low wines | Around 25% ABV, HMRC’s typical figure.[4] |
| Second distillation | Low wines join retained foreshots and feints for redistillation | Collected spirit averages 68 to 73% ABV in HMRC’s description.[4] |
| Cut to feints | Collection switches from retained spirit to material for redistillation | At 60% ABV in HMRC’s example.[4] |
These figures come from archived general guidance, rather than fixed settings for every distillery. The Scotch Whisky Technical File places the decision to collect the middle cut with the distiller’s judgement of the required quality.[1][4]
For a closer look at the equipment behind this sequence, see pot stills explained.
Heads, hearts and tails: selecting the spirit
The cut determines which part of a changing stream of spirit is retained for maturation. The first portion of a spirit run is called foreshots, often described as heads. The selected middle portion is the middle cut or heart; the later portion is feints or tails.[1][4]
The distiller chooses when to begin and end collection of that middle portion. HMRC describes the still operator watching the run at the spirit safe. The Scotch Whisky Technical File says the middle cut is collected only when the required quality has been reached.[1][4]
In HMRC’s account, foreshots and feints return to the low wines and feints receiver instead of joining the spirit retained for maturation. They remain part of the production cycle, mixed into a later spirit distillation.[1][4][6]
That cycle can bridge seasons. The SWA’s 1995 description records foreshots and feints being retained from the final distillation of one season for use with the first low wines of the next.[6]
The separate guide to heads, hearts and tails follows this selection in greater detail.
What changes with triple distillation?
Triple distillation adds a stage between low wines and the final collected spirit. Ireland’s registered technical file describes low wines being distilled into an intermediate spirit called feints, then distilled for a third time in a spirit still. In that description, the centre cut at the third stage establishes the final character.[7]
The change concerns composition as well as strength. The Irish technical file associates triple distillation with a higher final spirit strength and a particular ratio of higher alcohols to esters. Counting the vessels alone misses that shift in the spirit’s make-up.[7]
Triple distillation is a traditional Irish practice, but it is not required for every Irish whiskey. The same technical file describes double distillation as an alternative for pot still Irish whiskey. Nationality alone therefore cannot tell you how many distillations a particular spirit has undergone.[7]
How continuous column distillation works
A column still separates components continuously, rather than in the batches used by pot stills. The traditional Coffey or patent still has two columns: an analyser and a rectifier. HMRC compares their functions with those of the wash still and low wines still respectively.[1][5]
Wash enters near the top of the analyser as steam enters from the bottom. Spent wash leaves at the bottom, while spirit is drawn off in the rectifier. Other material returns within the process or is removed as fusel oil. Together, the columns carry out connected stages of separation.[5]
Column distillation can produce a lighter spirit without making it neutral. The Scotch Whisky Technical File explicitly states that grain whisky distillate is not neutral. The SWA’s 1995 account describes patent still spirit as generally lighter in aroma than most malt whiskies, a tendency rather than a universal column whisky style.[1][6]
The word grain does not identify the still, either. The Scotch Whisky Technical File records that grain Scotch can also be made by continuous distillation of wort from malted barley alone, or in a pot still from a mixed cereal mash.[1]
North American practice offers another variation. The Oxford Companion describes many bourbon and rye distilleries using doublers or thumper kegs for further partial rectification after column distillation. Even within a column system, the aim need not be the greatest possible separation at every stage.[9]
Why still design changes the result
The shape of a still helps shape the spirit’s sensory character, according to the Scotch Whisky Technical File. One important mechanism is reflux: some vapour condenses inside the still and falls back instead of passing directly to the condenser.[1][10]
A narrow neck or a very tall head increases reflux, producing a cleaner, stronger spirit, explains the Oxford Companion. “Cleaner” here describes greater separation, not a ranking of whisky styles.[10]
Pot stills separate less efficiently than columns, and that can be precisely the point. As the Oxford Companion puts it: “That very inefficiency leaves room for flavor.” The useful question is which degree of separation suits the intended spirit, rather than which still extracts alcohol most completely.[8]
Heating produces the vapour that can either condense inside the still as reflux or pass on to the condenser. HMRC’s archived account describes internal steam coils as the usual means of heating pot stills. The Scotch Whisky Technical File follows the vapour into condensers, where it becomes liquid again.[1][4]
Common mistakes about distillation
Higher strength can obscure what the still actually does, just as a column’s greater separation efficiency can obscure the character it retains. The useful distinction is between creating alcohol and concentrating it, and between lighter aroma and neutrality. Likewise, selecting a heart for maturation does not make the other portions waste: their role in the production cycle is described above.[1][2][3][4][6]
Where to go next
- Column Stills and the Coffey Still: follow the continuous process through its two principal columns.
- Double and Triple Distillation: examine what an additional distillation changes.
- Reflux and Copper Contact: Lyne Arms, Boil Balls and Purifiers: explore the features that influence separation.
- New Make Spirit: Straight From the Still: meet the spirit produced before maturation.
Sources
[1] UK Government. Technical File for Scotch Whisky, June 2019.
https://assets.publishing.service.gov.uk/media/5fd36667e90e07662ed92c85/Scotch_Whisky_Technical_File_-_June_2019.pdf
[2] HM Revenue and Customs. SPIR4080, Technical guidance: Stages of production: Fermentation, Spirits Production Manual, published 2016, updated June 2024. Archived January 2025 capture.
https://webarchive.nationalarchives.gov.uk/ukgwa/20250107121052mp_/https://www.gov.uk/hmrc-internal-manuals/spirits-production/spir4080
[3] HM Revenue and Customs. SPIR4090, Technical guidance: Stages of production: Distillation, Spirits Production Manual, published 2016, updated June 2024. Archived January 2025 capture.
https://webarchive.nationalarchives.gov.uk/ukgwa/20250107121052mp_/https://www.gov.uk/hmrc-internal-manuals/spirits-production/spir4090
[4] HM Revenue and Customs. SPIR4100, Technical guidance: Stages of production: Pot still distillation, Spirits Production Manual, published 2016, updated June 2024. Archived January 2025 capture.
https://webarchive.nationalarchives.gov.uk/ukgwa/20250107121052mp_/https://www.gov.uk/hmrc-internal-manuals/spirits-production/spir4100
[5] HM Revenue and Customs. SPIR4110, Technical guidance: Stages of production: Continuous distillation, Spirits Production Manual, published 2016, updated June 2024. Archived December 2024 capture.
https://webarchive.nationalarchives.gov.uk/ukgwa/20241231000000mp_/https://www.gov.uk/hmrc-internal-manuals/spirits-production/spir4110
[6] Scotch Whisky Association. Scotch Whisky: Questions and Answers, 1995. Copy hosted by the University of Edinburgh School of Informatics.
https://www.dcs.ed.ac.uk/home/jhb/whisky/swa/70.html
[7] Department of Agriculture, Food and the Marine. Technical File setting out the Specifications with which Irish Whiskey/Uisce Beatha Eireannach/Irish Whiskey must comply, October 2014 text. European Commission, eAmbrosia attachment 55944.
https://ec.europa.eu/geographical-indications-register/eambrosia-public-api/api/v1/attachments/55944
[8] David Wondrich. “still, pot”, The Oxford Companion to Spirits and Cocktails, reproduced by Spirits & Distilling.
https://www.spiritsanddistilling.com/dictionary/acref-9780199311132-e-690
[9] David Wondrich. “doubler, thumper, keg, and retort”, The Oxford Companion to Spirits and Cocktails, reproduced by Spirits & Distilling.
https://www.spiritsanddistilling.com/dictionary/acref-9780199311132-e-535
[10] Darcy O’Neill. “reflux”, The Oxford Companion to Spirits and Cocktails, reproduced by Spirits & Distilling.
https://www.spiritsanddistilling.com/dictionary/acref-9780199311132-e-649
This piece was prepared as desk research from the site’s verified fact sheet TOP-A434 and its accompanying editorial rulings.
Last checked: November 2026