How the Coffey still changed whisky
In 1830 an Irish excise officer patented a still that never had to stop. It made light, cheap grain spirit in huge volumes. Blended Scotch, much of Irish whiskey's decline and most of India's whisky all trace back to that design.
The pot still could only work in batches
For centuries whisky was made in pot stills: large copper kettles filled with fermented wash, heated, run and emptied. Making whisky that way needs two or three separate distillations, each one stopped and started by hand. Every run uses fuel to bring a full still back up to the boil.
The result is flavourful spirit, because pot stills carry a lot of the heavier compounds from the wash into the glass. The downside is cost. Pot stills are slow, use a lot of energy and work best with malted barley, which is more expensive than raw grain.
Coffey built a still that never stopped
Aeneas Coffey was an Irish excise official who left the service and went into distilling. Others had tried continuous stills, including the Scottish distiller Robert Stein a few years before. Coffey improved the design and patented it in 1830. It became known as the Coffey still, the patent still or simply the column still.
It has two tall columns. In the first, called the analyser, hot steam rises up through a stack of perforated plates while wash flows down over them. The steam strips the alcohol out of the wash. Spent wash, now almost free of alcohol, drains from the bottom. The alcohol vapour passes into the second column, the rectifier, where it is concentrated further. Spirit is drawn off near the top at a very high strength. Our guide on how a Coffey still makes grain whisky walks through each stage.
Cheap, light and continuous
The Coffey still had three big advantages. It ran around the clock as long as wash and steam kept coming. It used much less fuel per litre of alcohol, partly because the incoming cold wash was warmed by the hot vapour in the rectifier. It also worked well with cheaper cereals such as maize and wheat, with only a small share of malted barley needed for its enzymes.
Its spirit is far lighter in flavour than pot still spirit. Under today's Scotch rules, grain whisky must be distilled to less than 94.8% ABV so that some character from the raw material survives. Distil any higher and you are approaching neutral spirit.
Dublin said no and Scotland said yes
Coffey offered his still to the great Dublin distillers first. Most refused it. They were proud of their heavy pot still whiskey and saw the new spirit as thin and characterless. Scottish distillers in the Lowlands took it up instead.
That choice changed the balance of the whisky world. Scottish producers could now make large volumes of cheap grain whisky. Blenders learned to mix a little flavourful malt whisky with a lot of light grain whisky to make a smooth drink that suited a much wider audience. Once the law allowed blending under bond around 1860, blended Scotch grew into a global product. Irish whiskey, still committed to pot stills, slowly lost ground. The history of Irish whiskey follows what happened next.
Column stills spread far beyond Scotland
The design travelled. American distillers adapted it for bourbon and rye, usually running fermented mash, grain and all, through a single column often called a beer still. The spirit then goes through a second, simpler pot called a doubler or thumper. Because bourbon must come off the still at no more than 80% ABV, those columns are run far lower than a Scotch grain still, which keeps more corn and rye character.
Irish distillers eventually adopted column stills too, for the grain whisky in their blends. Canadian whisky relies heavily on them. Vodka and much gin start as column spirit. The floor detail that ties all of these together is the same one Coffey designed: live steam enters the base of the column and spent wash leaves the bottom almost free of alcohol, hour after hour, as long as the feed keeps coming.
It even forced a legal argument about what whisky is
By the early 1900s malt distillers argued that only pot still spirit deserved the name whisky. Grain distillers disagreed. A Royal Commission looked into the question and reported in 1909 that spirit from column stills was whisky too. That decision protected blended Scotch and grain whisky as legitimate categories.
Today Scotland recognises single grain and blended grain whisky alongside malt. Most of the Scotch sold around the world is still blended, built on column still grain whisky.
Most Indian whisky is a column still product
The column still matters especially in India. Modern multi-column stills, descendants of Coffey's design, turn fermented molasses or grain into extra neutral alcohol at around 95 to 96% ABV. That spirit is the base of most mainstream Indian whisky, blended with a share of malt and flavour. Our guide to molasses and grain spirit in India explains the feedstocks.
To taste the difference column distillation makes, pour a single grain whisky next to a single malt. The grain whisky is usually lighter, sweeter and smoother, with vanilla from the cask doing most of the talking. The malt carries more cereal, fruit and weight from the pot still. Two small measures with water alongside are enough to see it.
Common questions
What is a Coffey still?
A continuous column still patented by Aeneas Coffey in 1830. It uses steam rising through perforated plates to strip alcohol from wash without stopping, producing light, high strength spirit.
Is grain whisky inferior to malt whisky?
Not inferior, just lighter. Well matured single grain whisky can be excellent. Grain whisky is also the backbone of most blended Scotch.
Why did Irish distillers reject the Coffey still?
Most of the big Dublin distillers believed its spirit was thin and lacked the character of their pot still whiskey. Scottish distillers adopted it and used it to build blended Scotch.
