Glossary: C


The condenser is the part of the still used to condense the alcohol vapours (in other words, to turn them into liquid) by cooling them down. While for Vodka, Gin and Rum makers the condensing efficiency (and safety) is where most of the emphasis is placed, many Whisky and Brandy makers look at how different configurations impact the profile of the spirit itself. 

The size, shape and temperature of the condenser can make a difference to the flavour of the spirit. In Scotch, there have been many trials around old fashioned “Worm tubs” comparing them to shell-and-tube condensers to judge the impact on New Make spirit character. 

Much of the consideration lies around the length of the interaction between alcohol vapour and active copper, and how this influences whether a New Make spirit is light or heavy (the longer the interaction the lighter the spirit will be). It’s clear that the condenser configuration can play a role in prolonging or shortening the interaction.

Configuration aside, some distillers such as InchDairnie even play with different settings on the same apparatus and run cold water through their shell-and-tube condenser to make a heavy New Make, then switch to warmer water when they want to get a lighter character.

Cask Strength

Sometimes known as ‘barrel proof’, this refers to any aged spirit (typically whisky) that has not been diluted with water before bottling. Most spirits that are bottled at cask strength will state this term on the label and while it varies, as a drinker you can typically expect a cask strength product to be in excess of 50% ABV (100 proof).


Cuts refer to when the distiller makes a decision about the qualities of the incoming spirit and separates the distillate flowing from the still into separate collection vessels. There are numerous ways for a distiller to influence the flavour of their spirit, but the art of “cutting” is, in our opinion, one of the most important parts of the process for them to master.

Most distillers use parameters such as time elapsed since the distillation began, the volume of liquid that has been collected, the ABV of the distillate and the flow rate to help inform their decisions, but almost all will choose to use taste and smell to make the decision for when to make their cuts.

Gin makers have to be very careful about ensuring a slow and steady process to ensure that the full array of compounds are captured. Heat the still too fast and the volatile compounds will all arrive with the heads, while cutting too early will mean the hydrophilic compounds (which tend to be spiced, rooty and nutty) are lost in the tails and the resulting collected hearts lack in complexity and depth. 

Mezcal and Scotch producers tend to collect a fair amount of what many would deem as tails because it helps to accentuate the smoke aromas in their distillate. Some Mezcal producers even distil ‘to proof’ essentially forgoing making a tails cut altogether and running the collection for such a prolonged period that no water needs to be added before bottling as the collected distillate is already in-between their desired 40-50% ABV. 

In contrast, Bourbon producers often retain some of the heads which can favour certain esters developing further as the spirit ages in barrels, while Cognac producers separate tails into two in order to redistil some and discard the rest.

There’s a lot of science to what’s being collected in each ‘cut’ but ultimately, it’s the distiller’s nose and intention that defines what happens and how they want to shape their spirit.


Congeners are substances produced during the fermentation or distillation process other than ethanol. These substances include small amounts of chemicals such as methanol and other alcohols (known as fusel alcohols), acetone, acetaldehyde, esters, tannins, and aldehydes.

While many speculate on whether they contribute to hangovers or not, more importantly, congeners are responsible for many of the flavours in distilled alcoholic beverages and key to the distinctive character of a spirit. Brandy and Rum both have high amounts of congeners, while vodka has the least.

Type aside, some producers even test for the amount of congeners to make sure their spirit has a consistent flavour profile.

Carbon (Charcoal, Activated Carbon)

Carbon that is produced by heating wood or other organic substances in the absence of oxygen. When the oxidation of carbon is carried out by high temperature steam, millions of pores between the carbon atoms are created and the charcoal is classified as “activated”. For context, around one gram of activated carbon has a surface area of just under 3000 square meters. 

From a distiller’s perspective, the “activation” process creates a porous, sponge-like structure with a large surface area where many types of contaminants can bind to, removing them from the liquid (in essence a molecular filter and not dissimilar to a Brita filter for domestic use).

The density, size and distribution of the pores determines what compounds will be absorbed and which ones will pass through. Other than using it to clarify a spirit (for example to create a Cristalino Tequila or a White Rum), by using different types of activated charcoal, distillers also shape the final aroma and taste profile of a spirit.

Tennessee Whiskey makers were said to be the first to use charcoal to filter spirits and famously, the Lincoln Country process is where famous names like Jack Daniels and others are filtered through a column of maple wood charcoal. Today, activated charcoal is widely used in the production of Vodka and Rum, while many Tequila producers are now using commercial grades of activated charcoal as well.


Cristalino translates as “crystalline” in Spanish and refers to oak-aged Tequila that's been filtered through charcoal, removing the naturally occurring colours the spirit has absorbed from spending time inside a cask. As the name suggests it's generally crystal clear although some still have faint tinges of straw-like colour.

Due to the choice of carbon used by the distilleries, the aim of the filtration process is to strip a lot (if not all) the colour, reduce some of the tequila’s woodier notes, but to be deliberately less aggressive in removing the textures and vanillin like compounds imparted by the barrel. As a result, Cristalino is a hybrid style of Tequila, combining the barrel aged flavours of an Añejo (such as caramel, vanilla and oak), and the rawer Agave notes present in a Blanco, while also offering a rounded mouthfeel and smooth texture.


Curados is a sub-category of Tequila flavoured with natural ingredients such as lemon, orange, strawberry, pineapple etc... 

A minimum of 25% agave spirit must be used and often the rest of the fermentable sugars come from sugar cane or corn and the addition of sweeteners, colouring (and/or flavourings up to 75ml per litre).

Compound Gin

Compound Gin is a term that’s used for Gins that have been made without distillation. 

Compound Gins are commonly made by flavouring a Neutral Spirit base with essences or other natural flavourings. It is also possible to make them by steeping actual botanicals in a Neutral Spirit base (also known as a Bathtub Gin) and while that’s the most known and talked about (namely as their producers are proud to show how they are made and that there’s no hiding the natural tint that occurs to the liquid), there are far fewer of these gins than there are those who use essences and flavourings alone. 

Compound gins are less common in the UK and the US as they are in Spain or Belgium, where there are dozens and dozens of examples on shelf – not all of which are labelled as such.

Chill Filtering

Chill Filtering is a process that occurs before bottling and consists of chilling a spirit down to a very low temperature (often around zero degrees), and once chilled, passing it through a filter to pick up tiny particles before it has the chance to warm up again.

It’s a practice that is very heavily associated (and debated) in Whisky production, but there are also some Rum and Gin producers who use the practice. The reason that some distilleries choose to Chill Filter their products is that at less than 46% ABV a cloudy haze, also known as louche, can form in the bottle at low temperatures.

The haze is caused by flocculation, of which there are two types - reversible and irreversible. When it occurs in Whisky it is almost always due to the ethyl esters of long-chain fatty acids, and larger alkyl esters which formed during the production (linked to factors like cut points during distillation). Some extracts from cask maturation can also contribute to reversible flocculation too, while for gin makers, the haze is caused by having an excess of essential oils derived from the botanicals used. If you warm up a bottle to a normal room temperature, these types of hazing will simply disappear.

Sometimes the haze is actually irreversible floc however, which takes the form of very small crystals of calcium oxalate. This tends to be derived from the water used to reduce the spirit prior to bottling which may have high levels of calcium or magnesium. This type of hazing will not disappear once the spirit returns to normal temperatures, and little white crystals will float about the bottom of the bottle.

The Chill Filtration process recreates the ‘haze’ moment where the flocculation is visible and strips it out, preventing it from re-forming once at normal temperatures.


Charring occurs when the producers prepare casks to contain spirits by burning the inside of the vessel. Charring and Charred barrels are a big part of Bourbon production and the reason it tastes the way it does. As a result of its use there, charring is part of many other aged spirits that re-use American oak casks once they’ve been used for the Bourbon industry. 

The use of fire isn’t just to shape the oak stave into shape, it does a number of things for distillers. It helps to break down the structure of the oak allowing deeper permeation into the oak by the spirit. The cracks in the wood produced by charring also increase the surface area available to the spirit. These two factors help to increase the speed in which the desired interaction and maturation occurs.

Practicalities of aging aside, charring barrels is fundamentally also about flavour - without first heat-treating casks (even just a light toasting), whisky would mostly taste quite sappy. This is due to the structure of wood itself which, amongst other things, consists of cellulose, hemicellulose and lignin. When heated, they break down and create new and very tasty compounds which are soluble in ethanol. Because of this, it’s fair to say that charring increases the levels of vanillin in a spirit and spiciness and the heavier the char is, the lower the levels of tannin there are seeping into the spirit. This trade-off is why the level of charring is so carefully considered by Whisky makers.

To achieve the right level of char, casks are made in the standard fashion with toasted staves. Once the cask has been constructed the whole of the interior is then given a controlled burn. A No.1 char will see the cask be fired for around 15-20 seconds; No.2 for 30-40 seconds; and No.3 for around 45 seconds, while the No.4 Char sees the cask flame just under a minute.