Why And How Stills Influence Whisky

Hundreds of polished stills are boiling away in Scotland at this very moment, distilling new spirit to make more whisky. Each copper still is idiosyncratic, and they come in a surprising diversity of shapes and sizes. Copper pot stills may epitomize the Scotch whisky industry, but their job goes beyond being just a giant kettle designed to concentrate the alcohol. Stills are thoughtfully designed with flavor in mind and those elegant copper swan necks make a fundamental contribution to the final spirit character. A typical Scotch whisky distillery will have one or two pairs of stills, but there are numerous exceptions where they use extra stills (e.g. Glenfiddich), or where the distillation cycle is uncommonly complicated (e.g. Mortlach), or where triple distillation is preferred (e.g. Auchentoshan). To explore the relationship between stills and flavor, meet two distillers who make whisky in stills at either end of the spectrum: famously tall and curiously small.

Big Still

Equal in height to a full-grown male giraffe, the dozen stills at Glenmorangie are the tallest in Scotland, measuring 5.14 m or 16.9 ft. tall. At the Glenmorangie Company, the director of distilling, whisky creation, and whisky stocks is Dr. Bill Lumsden, though once upon a time, he was the Glenmorangie distillery manager. In his opinion, it has the finest stillroom in the world. “Visiting the stillhouse is a very spiritual experience, pardon the pun, but you can’t help but be impressed by our stills unless you’re an absolute cold fish!” says Bill. “It really is quite spectacular. The stills are as different as anything you’ll see anywhere else. With Ardbeg on the other hand, you have to be a real geek to “get it” and see what the key points of difference are. I’ve been in stillhouses that have made me gasp due to their geek factor and complication. A grain distillery stillhouse, for example, is a chemical engineer’s dream, but for all-around aesthetic beauty, the Glenmorangie stillhouse is hard to beat.”

The distillery was established in 1843, but rebuilt in 1887 by the Maitland brothers, who modeled the Glenmorangie setup on old gin stills. “They can’t possibly have not known that that would have had a profound impact on the characteristics of the whisky,” insists Bill. Forsyths of Rothes may have manufactured the modern stills, but the Maitlands are responsible for their magnitude. “Whether or not they wanted to make a delicate spirit, I suspect their target was to make a fast maturing spirit. Certainly, Glenmorangie is a fast maturing spirit and the delicacy from the tall stills adds to that.”

The stills at Glenmorangie are the tallest in Scotland, scraping the ceiling at nearly 17 ft. tall.

Little Still

Down in Speyside we find Russell Anderson, distillery manager at Macallan, a distillery known to whisky enthusiasts the world over for its curiously small stills. Auspiciously, he brings perspective from his lengthy tenure as distillery manager at Highland Park too. Russell conjures up the experience of visiting Macallan. “It’s very atmospheric when you stand in the stillhouse; you get the smells, the beautiful aromas of new make spirit, and the noise of the steam running through the pipes. It’s a wonderful place to be.” The new distillery building at Macallan is due to open in September 2017 and will include 36 new stills, each constructed to the same dimension and shape as the current ones. While the stills at Glenmorangie are known for their towering height, the stills at Macallan are comparatively small, accommodating less than half the volume of a Glenmorangie still. The apparatus couldn’t look more different. “We have small, squat, onion-type stills, very masculine and muscular,” observes Russell. “You could still class them as onion-shaped at Highland Park, but they’re much taller and larger, disappearing up into the roof space. You’ve doubled the spirit charge, and then some!”

The stocky stills at Macallan appear all the more remarkable because of the steep downward angle of the lyne arms, the pipework that connects the head of the still to the condenser. The length, diameter, and angle of the lyne arms determine how quickly the vapors condense back into liquid form. What effect does this have on the spirit character? “The main reason the stills are that shape, size, and dimension is that we love to produce a fruity, heavy cereal new make spirit. It’s waxy and oily, almost beeswax, with aromas full of cereal, yet it’s sweet and estery at the same time,” replies Russell. Macallan uses both Concerto and Momentum barley, but it’s the latter that holds the secret. “The Momentum gives us the oily qualities, which we believe carries forward in the stills. The other reason we’re able to get that oily, waxy note is because the stills are so small, so there’s much less reflux.”

The Reflux

Distillation concentrates the ethanol and highly flavorsome compounds to make spirit, while separating out the unwanted elements. Ever wondered why all stills aren’t a standard shape? Well, the degree of reflux plays a big part. The swan neck can shape the character of the whisky. They can have curvy adornments such as boil balls (the bulbous copper swelling at the base of the neck of a copper pot still), pinched, riveted waists, wide necks shaped like a lantern, plain straight columns, or flat tops. The shape of the swan neck can give the vapors a smooth ride or act as a baffle, leading heavier elements to condense against the copper surface and drop back down into the pot, leaving the lighter elements in the vapor to carry over the top.

If the size and shape of the stills are so important, how does this play out at Macallan? “As the alcohol vapors and flavor congeners boil up, they vaporize and climb up the swan neck and down into the condenser,” says Russell. “There are less opportunities for these compounds to hit the copper sides of the still and condense back into the pot again. The heavier alcohols and flavor congeners carry over the still at Macallan, primarily to give us this heavy, oily, sweet, waxy new make spirit that stands the test of time maturing in first-fill sherry oak casks.”

The tall stills at Glenmorangie, the Schwarzenegger to Macallan’s DeVito if you like, will produce a much lighter style. Bill explains, “The best way to compare would be to study a glass of Glenmorangie new make spirit alongside a glass of Macallan new make spirit. By its very nature, Macallan stands up well to full maturation in sherry casks, whereas ours does not.” The tall necks and the boil ball at Glenmorangie lead to a high degree of reflux. “Some of the longer chain compounds, the higher alcohols, and various fatty acids struggle to get over the tall necks at Glenmorangie. The consequence is that our spirit is very clean, very fresh, and very delicate.”

Want to see different stills and equipment in action? Visit these Scottish distilleries

Worm tub at Ballindalloch distillery (Photo by Jonny McCormick)

The Condenser

The vapors exit the still via the lyne arm. Most lyne arms are angled downward, some are ascending, and some are quite oddly shaped, depending on which direction the distiller wants any condensed liquid to flow: refluxed backward into the pot or trickling forward toward the condenser. The condenser is the copper structure where the alcohol-rich vapors exiting the lyne arm are turned back into liquid form by contact with surfaces cooled by water. Condensers come in two types: worm tubs and shell-and-tube condensers. Worm tubs are arguably more traditional, but the shell-and-tube condenser is the most ubiquitous form.

The copper pipework in a worm tub spirals under water, tapering in diameter as it dives down to where the coldest water is fed into the tub. The system and principles are no different to the smaller versions once used by illicit distillers. The constant need for cooling water is one of the reasons that distilleries are built beside sources of plentiful cold water.

The most common form of condenser at a malt whisky distillery in Scotland is the shell-and-tube. Vapor flows into the shell, condensing against the outer surface of the densely packed copper tubes pumped full of circulating cold water. Picture it like a box crammed with drinking straws: this produces a tremendous surface area of copper, many times greater than a worm tub, which vastly increases the copper conversation.

Raw spirit produced through worm tubs has a meaty, sulfury character. This is significantly reduced in distilleries with shell-and-tube condensers due to the enhanced copper contact, as Bill acknowledges: “The method of condensation, shell-and-tube condenser versus worm tub, has a massive impact on the character of your spirit. Worm tub whisky can sometimes be a bit brutal and unforgiving,” he says, but they are enjoyable malts to conquer. “Think about Diageo’s amazing Benrinnes distillery, which produces a really meaty, sulfury whisky, or Mortlach, which has these nice sulfury notes, although it is a bit more restrained. Benrinnes, more than any other malt whisky I can think of, divides opinions among drinkers, if you ignore the peating factor. I like it because of the curiosity value, but it wouldn’t be my everyday drink.” For the style of whisky they make at Glenmorangie, worm tubs simply would not do. “The shell-and-tube condensers produce a much cleaner spirit because of the higher surface area of copper; it’s at least 20 times greater compared to a worm tub.”

A stillman closely monitors the spirit safe at Oban distillery (Photo by Jonny McCormick)

The Cut

The size of the “cut” chosen by the stillman is the final determinant of spirit character. The cut, sometimes referred to as “the middle cut” or “the heart,” is the distillate that is separated from the undesirable foreshots (the first fraction to run off the spirit still) and feints (the final fraction from distillation after the middle cut) and collected off the still through the spirit safe to mature into whisky. It should match the distiller’s intended character and flavor profile. “The size of the cut is important,” urges Russell. “We have a very small cut at Macallan: we cut at 68 percent alcohol by volume. Highland Park is more straightforward and the cut is down to 66 percent, sometimes 64 percent. The reason is that we want more phenols to come through.” Phenols distill off later in the spirit run. If you cut the Highland Park new make spirit the same as Macallan, you would lose quite a bit of phenol character.

“There is no question that a number of distilleries have very large spirit cuts,” Lumsden discloses. “I’ve worked at distilleries where the spirit cut was almost 40 percent of the charge. At Glenmorangie, it’s 16 percent.” Like Russell’s time on Orkney, Bill has to ensure his Islay spirit picks up its characteristic peaty notes. “We take Ardbeg more into the feints, and take a larger cut because we are trying to capture more of the phenolic compounds. The purifier at Ardbeg and the relatively small spirit cut [it’s 21 percent] means that we are still capturing a lot of the fatty acid esters, the aldehydes, and the ketones that you just don’t find in the taste because there is so much peat smoke.” Bill attests that if you analyze the congeners in Ardbeg and Glenmorangie spirit, there are many similarities, as they want the complexity to balance out the peat smoke.

With such diametrically different new makes, do the casks at Macallan need to work a bit harder as a consequence? “The very robust, sweet, cerealy, and waxy new make spirit that we make is designed to harmonize and marry with the wood,” points out Russell. Macallan is usually quite a full, maturing whisky, which is typically matured in first-fill sherry American and European oak casks. “We invest a huge amount in wood, to make sure we get the same quality of whisky time and time again,” confirms Russell. “If you were to put a very light new make spirit like Glenmorangie into 100 percent first-fill sherry European oak wood, you would produce a very different whisky altogether. The new make spirit would not be able to stand up against the wood, or work with it. In fact, the wood would overpower the more subtle, lighter flavors in the majority of cases.” 

For most whisky drinkers, does understanding how it’s made enhance the experience of drinking whisky? “If you really love your whisky, then yes, you want to know more about it,” encourages Bill. “People will drink Glenmorangie Original or Glenmorangie 18 year old and they’ll marvel at the floral complexity. I think a lot of people want to know where that comes from and it is as a result of distillation. I can only believe that all the base compounds are present in the fermented wash at Glenfiddich, at Glenlivet, at Macallan, at Glenfarclas, and Glenmorangie, but it’s how it’s distilled that largely determines how you’ll experience the final product” he states, before adding, “along with the choice of cask obviously.”

Which whisky would Bill Lumsden recommend to truly experience the tall still effect? “My absolute recommendation would be to try the new make spirit. Unfortunately, that privilege is only open to a select few, so Glenmorangie Original is the best starting point.” Russell Anderson’s answer to the conundrum is simple, “Even within our own company, people will ask me what is it that makes Macallan that bit different? I just say, get someone to taste it. You can speak about it till the cows come home. Get someone to put a drop in their mouth and let them taste it.”

More From Insights