Apologies for the late follow up to this.
Sometimes, life just gets in the way of me geeking out to the next level. Thankfully a long weekend allowed for better recharging and more time for learning and refreshing. In part 1, I discussed how fermentation affects the production of a spirit. In this part, I’ll talk about distillation.
To produce a spirit, distillation is an essential process. This process is about separating components of a mixture via selective boiling and condensation. Think of is as an enclosed water cycle. The wash is the water. The heat source, whether direct flame or steam coils, is the sun’s substitute. A still’s condenser takes the place of the clouds where the evaporated vapor, in this case distilled, gets cooled down and leaves the still as new make. Because the topic is single malt Scotch, I will only talk about pot stills.
Distillation – Cuts
Distilling the wash is meant to separate water from ethanol and other compounds you want in your spirit. This is why spirits have a higher ABV than fermented alcohol such as beer or wine. The more a wash and/or spirit is distilled, the less water there is. Less water also means other compounds like methanol and ethanol become more concentrated, hence the need for separating the heads, hearts, and tails.
The heads cut contains methanol. Having a lower boiling point and being the lightest in weight, methanol always comes out first. Too much of this is what causes blindness, paralysis and even death when consuming spirits from someone who doesn’t know what they’re doing.
Hearts are what the distiller wants as all the ethanol and pleasant notes are in there.
Tails have the “off” or unpleasant flavors, which is why the heads and tails are either sold by the distillery or re-distilled in the next batch. Some distillers choose to allow some heads and tails to be mixed in their new make to be aged. The funk in Jamaican rum is said to come from the addition of tails cuts. With that logic, it’s safe to say that some single malts considered to have funk also have tails mixed into them.
Aging in oak is said to detoxify the methanol in heads and improve the flavors from the tails. (Charred oak is somewhat like charcoal, used for filtering.) This is why some distillers like to talk about cuts. Cuts not only affect a spirit’s flavor, but also its texture. This is why some whiskies of the same ABV, which isn’t chill-filtered, can have varying textures such as oiliness.
Distillation – Still Shape
You may have noticed that some distilleries like to talk about how tall their stills are. The best-known example would be Glenmorangie, which is proud to have the tallest (or one of the tallest) pot stills in Scotland. Aside from being a unique selling point, the shape of a still has an effect on a spirit. It’s said that taller stills produce a lighter spirit. This is due to congeners being heavy. Because they are heavy, they slowly fall off from the rising steam, which comes out as new make spirits at the end of distillation.
A generalized explanation I heard before is: taller stills = more reflux. More reflux = less flavor. Reflux essentially refers to the condensed vapors that return to the base of the still where a wash or spirit is being distilled.
The lyne arm is the part of the still that connects to the condenser. This is what the distilled vapors pass through to get to the condenser. The angle degree of the lyne arm is also said to affect the flavor of a spirit. Certain angles are said to produce citrus flavors, but since the angle of lyne arms is rarely discussed, this is all I know about the topic.
While single malts are all made in pot still, not all shapes of pots are the same. For example, Clynelish’s still shape is a neck ball. Glenlivet’s still shape is a traditional Speyside with a lamp glass. Springbank has an onion-shaped still. With other factors such as fermentation time, speed of distillation and condensers, it’s pretty hard to guess what kind of exact flavors the shape of a still will produce. It’s also due to still shapes being under-discussed, but we are sure that these three single malts from three different still shapes are very different from each other.
Glenlivet’s traditional Speyside with a lampglass.
Springbank’s onion still.
Condensers are the part of the still that turns the new-make, in the form of vapor, into liquid. Much like in the water cycle, evaporated vapor has to reach lower temperatures in order to condense into liquid. This is why a water source is important for distilleries; aside from water being needed for fermentation, cleaning and diluting, water is also needed for condensing.
There are two main types of condensers. The older and less popular one is called the worm tub (a.k.a. Serpentine coil). This was invented by Christian Weigel in 1771. Worm tubs are known to produce a heavier, sulfuric, and meaty spirit. I think there are only 16 single malt distilleries left in Scotland that use this type of condenser. (Some might say 15.5, since Springbank uses both a shell & tube and a worm tub). Aside from consumers preferring a lighter tasting spirit these days, worm tubs aren’t as popular today due to them being inefficient in space. Just look at the image of Mortlachs’ worm tubs below. Worm tubs take up a lot of space!
The tops of worm tubs are open due to how they work. Cold water is pumped into the bottom while hot water is removed from the top. Sulfur is produced during distillation. Copper is one of the best materials for separating sulfur from distillates; despite the size, worm tubs have less copper contact, which means they’re not so good at sulfur separation.
Even though worm tubs are generalized to produce heavier spirits, a distiller can choose to make the spirit light or heavy by adjusting the flow of water. A faster flow of cold water = faster condensation = less copper contact = a heavier distillate. A slower flow of cold water = slow condensation = more copper contact = a lighter distillate.
Shell and tube.
The other and more popular type of condenser is called shell and tube. This was invented in 1825 by William Grimble. It was in the 1880s when it became more used by the Scotch industry. Shell and tubes are more popular because they produce a lighter spirit and are more space efficient. (Look at the image of Glengoyne’s still below. Shell & tubes requires much less space!)
Lighter spirits are produced due to there being more copper contact. Despite looking simple, the workings of a shell and tube are complex. The shell is the exterior thing you see, while the tubes are inside. My basic understanding of it is: there’s an exchange of hot and cold liquid around the tubes. While this type of condenser is known to produce a lighter spirit, I’ve read it can also produce a heavier spirit by lessening the tubes and copper contact. Clynelish would be the most popular example, but I’ve heard Clynelish’ “heaviness” is partly due to how “dirty” the distillery is.
Barrel Entry Proof
This refers to what proof the new-make spirit enters the barrel or cask. These days, the new-make spirit leaves the still at around 60% to 70% ABV. Some distilleries dilute the spirit for a bit before putting them in casks. Some put the new-make spirit in casks at still proof. Despite the technology we have today, it’s still pretty hard for a distillery to ensure their new-make leaves the still at exactly one specific ABV per batch of distillation.
We all know that the interaction between the spirit and the cask is what gives it color and more flavor. But, what most aren’t aware of (or don’t realize) is that the ABV of the spirit affects the rate of this interaction. Alcohol is a solvent, so the higher the ABV, the faster this interaction is.
Because of the “the higher the ABV the better” narrative going around, a lot of cask strength fans might be thinking that a high barrel entry proof might be better. This may not necessarily be true. A faster extraction rate of cask influence could mean the flavors won’t be so well integrated into the spirit. Also, due to alcohol being a solvent, it could also mean the faster wearing down of casks.
This idea made more sense to me when I got to compare bourbon bottled in the 1960s. In 1962, bourbon’s barrel entry proof changed from a max of 110 proof to 125 proof. These dusty bourbons taste more balanced to me compared to most of today’s bourbon. By balanced, I mean I get to taste more of the distillery’s DNA. I find this easier to drink more often, or for longer periods of time compared to today’s mostly overly oaky bourbon.
There are other topics I want to tackle but know little about. One of these is the speed of distillation. I only hear and read bits online. Some say that to cope with demand, some distilleries are distilling faster. This faster distillation is said to result in a hotter spirit that has more burnt and off flavors.
I’m keen on agreeing with this since Glengoyne boasts of their slow distillation. These days, it’s one of the few Scotch single malt brands where I don’t get any off flavors. Some distillers who work for smaller non-whisky brands also emphasize the importance of slow distillation.
The other topic is the heat source of distillation. The two most popular ones today are steam coil and direct fire. Steam coil is the most popular among the two. It’s largely due to being more environmentally friendly and the temperature being easier to control. The knock against this is it’s not traditional and it can’t reach as high a temperature as direct fire.
Just for additional notes: Cognac is required to be distilled in direct fire contact pot stills with worm tub condensers. Nikka’s Yoichi and the Springbank Distillery are also some of my favorite distilleries that use direct flame.
In conclusion to my premise in part 1: independent bottlers will almost always have no say in control over what their distilleries they source from do, unless it’s companies like Signatory bottling Edradour or Ballechin, which they own. If you’re not a fan of the contemporary bottlings of your favorite independent bottler brand, it’s not entirely the fault of the company. Put more responsibility on the distillery producing the whisky. Hopefully you’ve learned that a whisky’s quality isn’t just dictated by being bottled at 46%, non-chill filtered and no added coloring.
Images of stills and worm tubs courtesy of Whisky.com