Whisky glossary

Navigating the world of whisky sometimes requires a compass. This glossary aims to untangle some of the most common terms that trip people up when it comes to the production and enjoyment of whisky
Whisky glossary

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ABV – alcohol by volume is the strength of the spirit, measured in percentages  

American Standard Barrel – a 200-litre wooden vessel made from American oak used for maturing American whiskey is called an American Standard Barrel. By law, Bourbon must be matured in new, charred oak barrels. In recent years, Scotch whisky producers have used these first-fill ex-Bourbon barrels to mature their new-make whisky. American Standard Barrels, or barrels for short, typically impart vanilla, spice, coconut and caramel characteristics to the final whisky. 

Angel’s share – as a spirit matures in barrel, some of the liquid naturally evaporates – concentrating the whisky that is left behind and reducing the alcohol level. The proportion of spirit that evaporates (around 2-3% each year) is rather whimsically known as the “angels’ share”. 

Barrel – see American Standard Barrel above

Barrique – the French term for “barrel”, barriques are normally made from French oak and are used in the maturation and transportation of wine. The 225-litre Bordeaux barrique is sometimes used to mature Scotch whisky. The 300-litre Cognac-type barrique is less commonly used in the Scotch whisky industry.  

Blended grain whisky – a blend of two or more single grain whiskies, distilled to no higher than 94.8% alcohol. By law, blended grain Scotch whisky must be distilled and matured in Scotland. It can be blended before or after maturation. 

Blended malt whisky – a blend of two or more single malt whiskies, distilled to no higher than 94.9% alcohol. By law, blended malt Scotch whisky must be distilled and matured in Scotland. It can be blended before or after maturation. Traditionally, blended malt whisky was called vatted or pure malt whisky.  

Blended whisky – the workhorse of the Scotch industry, blended whisky (which accounts for over 90% of global sales) is made by combining grain and malt whisky.  

Blood tub – the smallest whisky cask, blood tubs, hold 30-50 litres. Due to their size, these casks are no longer used in commercial production but are occasionally offered to private clients.  

Bonded warehouse – goods can be stored prior to the payment of tax or duty in a bonded warehouse. This is practical especially if you plan to sell wine or spirits further down the line. a storage facility where goods are stored before they are processed and duty is paid is called a bonded warehouse.

Bourbon – an American whiskey made from a mash bill of at least 51% corn. The second grain in 95% of Bourbon is rye, which gives it a spiciness. The other 5% of Bourbon has wheat in place of rye – these wheated Bourbons are softer, as the fruit notes from the corn are accentuated by the addition of wheat. Contrary to popular belief, Bourbon can be made anywhere in the United States but the vast majority (95%) is produced in Kentucky. Bourbon must be distilled no higher than 160 proof (80% alcohol) and matured in newly charred (virgin) American oak barrels. “Straight” Bourbon must be matured for a minimum two years. Bourbon was first produced in Kentucky in the 1780s when distillers discovered charring barrels mellowed corn whiskey.  

Butt – a large oak cask which holds 500 litres is called a butt. The majority of butts are made from European or Spanish oak but some are made from American oak. Sherry butts are commonly used in the Scotch whisky industry and impart rich, fruit-forward characteristics on the final profile. The Macallan is famous for using Sherry butts to mature its Highland single malt. 

Campbeltown – Campbeltown was the whisky capital of the world during the late 19th century, with 30 distilleries at its height. Today, there are only three active distilleries in Campbeltown, making it the smallest whisky-producing region in Scotland. Whiskies from this region, located at the most southerly tip of the Kintyre peninsula, are typically fruity, peated and smoky with subtle saline characteristics from the maritime influence. Springbank is probably the most famous name from the Campbeltown region.   

Cask – a wooden vessel of any size used for the maturation of spirits (or wine). According to regulations, Scotch whisky must be matured in an oak cask, in Scotland, for a minimum of three years.  

Cask strength – when a whisky is bottled straight from the cask without any dilution. Most whiskies have water added to bring the ABV down to 40-50%. 

Charring – a heat treatment applied to casks. All Bourbon whiskey barrels must be matured in new, charred oak barrels. The process, which involves applying flame to toasted staves that have been shaped into barrels, breaks down the oak structure, enabling greater interaction with the spirit. Charring also acts as a filter, removing undesirable characteristics, like sulphur, in the whiskey. There are four charring levels which increase according to the time under flame (char = 15 seconds, char 2 = 30 seconds, char 3 = 35 seconds and char 4 = 55 seconds). The heavier the char, the greater the layer of charcoal on the staves – known as alligator char. If a cask has been used many times, it can be rejuvenated by a process called de- or re-charring. This involves a few millimetres of the barrel being removed before it is exposed to flame again. 

Chill-filtering/chill-filtration – the method of chilling a whisky down to around 0˚C and passing it through a filter to remove certain esters (compounds responsible for aromas and flavours), fatty acids and proteins that are naturally produced in whisky production. Some producers remove these to ensure the whisky doesn’t appear cloudy or hazy when it drops below 46%, normally when water or ice is added. Some believe chill-filtration compromises the final flavour and complexity of the whisky. 

Coffey still – the eponymous still patented by Aeneas Coffey in 1830 is a refinement of the column still which is used in the continuous distillation of spirits. This process is invariably cheaper and more efficient than the batch distillation method but cannot be used to produce Scotch whisky, which by law must be produced in a pot still. Coffey/column stills typically produce a lighter and higher-alcohol spirit such as vodka, gin or American whiskey.  

Column still – also known as a continuous still, patent still, or Coffey still, a column still consists of two columns which contain several heated plates that are capable of producing spirit in a more efficient way, and to a higher alcohol percentage, than the traditional pot still. Each plate contains small holes which allow steam and spirit vapour to rise and condense. Column stills are commonly used in the production of high-alcohol spirits such as vodka, gin and American whiskey. 

Condenser – a part of the still which condenses alcohol vapours by cooling them. Condensers come in various sizes and shapes. In Scotch whisky-making, the two most common condensers are traditional worm tubs and the more modern shell-and-tube (see respective entries for more information).  

Cooperage – where casks are produced by a cooper. Traditionally, these were located within each distillery. In recent years, most distilleries have outsourced coopering.  

Direct-fired – the process of heating a still with a direct flame. Traditionally, all stills were direct-fired but many switched to indirect fire (heated by steam) in the mid-20th century. A handful of distilleries continue to direct-fire their stills, believing the more costly and energy-inefficient method adds distinctive weight and body to their final spirit character, such as Glenfarclas and Springbank

Distillation – the process of heating a liquid and condensing it to collect the vapour. Most Scotch whiskies are distilled twice. Distillation occurs after fermentation. The wash is poured into copper pot stills and heated by steam (indirect) or fire (direct). Once heat has been applied, alcohol evaporates and condenses through the swan neck into either shell-and-tube or worm tub condensers. The cold water in the condenser turns the alcohol vapours back into liquid. After the first distillation, the alcohol – known as low wines – is distilled a second time to separate the undesirable characteristics. The Master Distiller will closely monitor the liquid in the spirit safe and make a cut. The first liquid to arrive is known as the heads or foreshots – this is very astringent and is consigned to the feints receiver. The next spirit is the most desirable and is known as the hearts – this liquid will become the new-make whisky that is matured in oak casks. The final spirit to be received is known as the tails, or feints. This is re-directed to another container and can be re-distilled or discarded. 

Distillery character – each distillery has its own subtle (or not-so-subtle) characteristics depending on the shape and size of their stills, fermentation and distillations methods, their preferred casks and maturation conditions.  

Dram – a poured serving of whisky, typically 28-35ml, also used colloquially to reference Scotch whisky 

Dunnage warehouse – a traditional warehouse used to mature whisky, low in height with brick or stone walls and an earthen floor. 

European oak – or quercus robur, is a species of wood commonly used to cooper casks for whisky maturation. The highest quality European oak casks go through a two-stage process of being seasoned and kiln-dried or air-dried for up to five years. Traditionally, European oak barrels are toasted under a gentle flame for up to 15 minutes which imparts a spicy, clove characteristic on the final whisky profile. 

Excise Act – passed in 1823, the Excise Act legalised the distilling of whisky for a £10 licence fee, and set payment per gallon of proof spirit. Illicit distilling and smuggling died out as a result and many modern-day distilleries were built on these sites.   

Feints – also called “tails” or “aftershots”, feints are the unusable last portion of liquid collected at the end of the second distillation run in a pot still during Scotch whisky-making. These can be re-distilled or discarded.  

Fermentation – the process of converting grain sugars into carbon dioxide and ethyl alcohol through the addition of yeast. Fermentation times vary from distillery to distillery. The industry average is around 50 hours but there has been a notable increase in fermentation times in recent years which many believe produces a more estery, fruit-forward spirit. Shorter fermentation times tend to produce more nutty, cereal notes.  

Filling strength – the alcohol strength of the whisky filled into a cask. In Scotland, this is typically 63.5% alcohol for malt spirit and 70-71% alcohol for grain spirit. There are strict regulations in the United States on filling strength, with it forbidden for barrels to be filled at more than 62.5% alcohol (125 proof). 

First-fill – casks used for the first time after their original use. Typically, first-fill casks are ex-Bourbon barrels which can only be used once according to American whiskey regulations. 

Floor malting – the traditional process of malting barley by hand. After the grain is steeped, it is evenly spread onto a concrete floor where it starts to germinate. During this process, the damp grains (known as green malt) are turned every eight hours to prevent them from growing roots. Once the requisite sugar and enzymes have been produced, maltsters collect the grain and move it into the kiln to end the malting process. Historically, most producers floor-malted in buildings on-site but a drive to cut inefficiencies in the 1950s and ‘60s meant a glut of floor maltings were closed and this process was either outsourced to dedicated floor malting companies or they switched to alternative industrial methods. Laphroaig is one of the few producers who still boast on-site floor maltings. 

Foreshot – also known as heads, the foreshot is the initial 2% of the second distillation run. It smells like nail varnish or solvent and is either discarded or re-distilled. 

Germination – the process that occurs after grain is steeped in water. Damp barley, known as green malt, is transferred to a carefully controlled environment where it is allowed to germinate for up to five days. During this process, which traditionally took place at on-site floor maltings but is commonly outsourced today, the aim is to break down the cell walls of the grain to release protein and starch. After germination, the grain is sent to the kiln for drying.  

Grain whisky – a whisky made from cereal grains (such as corn, wheat and rye) that has been distilled in a continuous column still. While single grain whiskies do exist, the vast majority of grain whisky is blended   

Highlands – geographically speaking, the Highlands is the largest whisky-producing region in Scotland. Somewhat confusingly, the Highlands includes Speyside and producers from the Speyside region can label their whisky as a Highland single malt. The Macallan is probably the most famous example of this. Today, Highland whisky styles vary greatly and can be heavily peated, light and heathery or smoky. Some of the most coveted Highland single malt producers are The Dalmore, Glenmorangie and Balblair

Hogshead – the second most common cask used in Scotch whisky maturation, the hogshead is a large, 250-litre cask constructed from dismantled ex-Bourbon barrels (or in some instances Sherry casks) with additional staves and new ends. The exact origin of the term is unknown but theories abound. 

Independent bottler – companies who buy young or mature spirit from a producer or third party and sell it under their own branding are called independent bottlers. The single malt Scotch whisky industry largely exists today thanks to the likes of Gordon & MacPhail, who laid down stocks and independently bottled Scotch when distillers faced financial difficulty and closure.   

Indirect-fired – the process of heating a still with steam which was introduced by Glenmorangie in 1887 and more widely adopted when distilleries modernised in the 1950s and ‘60s. Steam jackets (lining the outside of a still) or the more modern and widely used steam coil (inside the pot still) are more heat efficient and cost effective solutions compared to the traditional process of direct-fire (using a flame). The vast majority of Scotch whisky distilleries indirect fire their stills.  

Islay – located on the southernmost island of the Inner Hebrides, Islay traditionally produced whiskies that elevated some of the world’s most well-known blended malts. In recent years, the small island has produced some of the world’s most lauded single malt whiskies. At last count, Islay boasts nine distilleries, including Bowmore, Ardbeg, Bruichladdich and the soon-to-be revived Port Ellen.  

Islands – a catch-all term for the small, Scottish whisky-producing islands, excluding Islay. Some of the most well-known exports are Scapa and Highland Park from Orkney, Talisker from the Isle of Skye, and Jura and Arran from their eponymous islands. The whisky styles from the so-called islands vary greatly.  

Kiln – a traditional working kiln, complete with the iconic pagoda, is a rare sight in Scotland today. During whisky-making, still-germinating barley – known as green malt – is fed into the kiln where it is traditionally heated by a furnace. This stage performs three important functions: stopping the barley germinating, drying the green malt to remove the moisture content so it can be milled, and – for some producers – adding a desired peated smokiness to the malt and resulting whisky. 

Low wines – the product of the first distillation stage in a pot still is known as the low wines. In Scotch whisky production, this spirit, which is 20-25% alcohol, is collected in the receiver for re-distillation.   

Lowlands – the Scottish Lowlands was once a thriving whisky region, home to many distilleries. Throughout the years, the number of producers has contracted – the 1920s being especially painful for the region – and only a handful remain. The region might be small in terms of producer numbers but its output is sizeable, with vast quantities of grain whisky and malt whiskies produced, predominately destined for blends. In terms of single malts, the most famous Lowland names are the likes of Auchentoshan, Daftmill and lost greats like Littlemill and the resurrected Rosebank. The region was traditionally the home of triple-distilled whisky, a practice commonly associated with Irish whiskey producers. Auchentoshan still triple-distils its whiskies but the vast majority of others adopt the more traditional Scotch process of double distillation. The number of distilleries in the region is on the rise with Daftmill built in 2005 and Alisa Bay built in 2008. Typical Lowland whisky characteristics are light and grassy with floral notes.  

Lyne arm – a copper tube connecting the head of the pot still to the condensing system (either a shell-and-tube or worm tub). The angle of the lyne arm varies from distillery to distillery. If it is angled upwards, the lyne arm typically creates more reflux, in turn producing a lighter whisky. If the lyne arm is positioned downwards, the inverse is true and a more heavy spirit character can be produced.  

Malt whisky – a type of whisky produced from malted barley 

Malting – the first stage in Scotch whisky production is known as malting. Traditionally, the grain was soaked in water and evenly spread onto the floor of the malting house. The grain is turned regularly by maltsters in carefully controlled conditions for approximately five days until the grain starts to germinate – known as green malt. This is when the barley is transferred to the kiln and heated to stop further germination. 

Marrying – the process post-blending, pre-bottling when the whisky rests allowing the flavours to “marry”. The length of time will depend on many factors, including the spirit and the size of the vessel. This typically takes place in a neutral vessel that won’t add any additional flavour.

Mash bill – the mix of grains that are fermented and distilled to produce American whiskey. For Bourbon, the mash bill must be a minimum 51% corn; for rye whiskey, the mash bill must be a minimum 51% rye. Every producer’s mash bill differs and is a closely guarded secret.   

Mashing – after the barley is malted it is sent to a malt mill where it is ground into grist. Hot water is added to this mixture and stirred. The solids are removed to produce a sugary liquid named wort. During mashing, starch in the barley is converted into sugar that will be converted into alcohol in the next stage of the production process, fermentation.  

Master Blender – the Master Blender is responsible for ensuring there are sufficient stocks of the right age/style to create consistent blends for the distillery, as well as deciding when whiskies (including more limited, special releases) are ready to be bottled. This is normally the equivalent level to the Master Distiller or winemaker  

Master Distiller – a prestigious, and relatively modern, title that tends to denote a senior level of production knowledge. The Master Distiller is normally responsible for all the high-level production decisions at a distillery or distilleries.  

Maturation – the ageing of whisky, normally in barrel. By law, Scotch whisky must be matured in an oak barrel in Scotland for a minimum three years. During the maturation period, the cask will impart desirable flavour and colour characteristics. In recent years, many producers have opted to transfer their whisky into a different cask for an additional maturation period which is known as cask finishing or secondary maturation. The liquid that evaporates during maturation is affectionately referred to as the angel’s share.  

Milling – the process when malted barley is milled into a powder known as grist which consists of husk, grit and flour. Milling is key to ensuring sugars can be extracted during the mashing process. 

Mizunara – a species of oak indigenous to Japan that is used to mature whisky. Quercus Mongolica Crispula or Quercus Crispula is incredibly problematic to cooper, source and use as a maturation vessel. The mizunara oak tree takes approximately 200 years to reach maturity, does not grow in a straight line, has high moisture content (mizunara literally translates as water oak), and contains more knots than other woods. It is also porous and prone to leakage but is very desirable because it is so rare. Mizunara casks tend to impart slightly unusual characteristics of sandalwood, coconut and incense on whisky.

NAS – stands for “No Age Statement”, this is a whisky without a stated maturation age on the bottle. By law, all Scotch whisky must be matured for a minimum three years. When an age statement is declared, this is measured by the youngest liquid in the bottle, not the oldest. There are many remarkable whiskies that do not carry an age statement, like the single malts from award-winning Taiwanese producer Kavalan.  

New-make – the colourless, high-alcohol liquid that is collected from the still after the distillation process. In order to be bottled as Scotch whisky, new-make spirit must spend a minimum three years maturing in an oak cask in Scotland.  

Octave cask – a 50-litre barrel, a quarter of the size of an American Standard Barrel. Octave casks are often used for shorter maturations and secondary maturation periods because the interaction between wood and spirit is intensified due to higher wood-to-liquid ratio. 

OLA – “Original Litres of Alcohol” is the level when the casks was initially filled. This is a useful figure when determining how the whisky has changed during maturation within a certain cask. As a guide, if a cask was filled with 100 litres of new-make spirit at 50% alcohol, there would be 50 litres of pure alcohol in the cask, so the OLA figure would be 50 OLA. 

Pagoda roof an iconic pyramid-shaped chimney, invented by Charles Doig and modelled on Asian architecture. The pagoda roof, which is largely aesthetic now most producers buy in their malt, was traditionally used to dry malted barley. The pagoda was designed to improve the air flow for the smoke from the kiln.  

Peat – literally the top layer of turf/soil, that is particularly rich in organic matter and therefore carbon, peat is a natural vegetative fuel source that was traditionally used in some parts of Scotland to heat pot stills. Producers would cut slices from peat bogs which formed over hundreds and thousands of years, and dried them to use as fuel (there were few trees, and coal and oil were in short supply at the time). Confusingly, perhaps, the smoky and peated characteristics, commonly associated with Islay, are not imparted by this traditional process. Those peated flavours are the result of drying damp malt (green malt) over fires that are heated by peat. The resulting, smoked barley is then used in the whisky production process. The longer the barley has been exposed to the peat smoke during the malting process, the stronger the peat level, which is meased in PPM (phenol parts per million). 

Peated whisky – a popular whisky style that is produced when barley is malted over a peat-heated fire. Traditionally, this style of whisky was made across Scotland but, as producers have moved to different and more efficient production methods, peated whisky is now most commonly associated with the Hebridean isle of Islay, but is also being recreated further afield.   

Phenols – chemical compounds produced when peat is used in the malting process. Phenols are measured in ppm (parts per million).  

PX cask – a cask that previously held or has been seasoned with Pedro Ximénez Sherry, often used in the maturation of whisky. Time spent in PX casks will often impart a rich, dried fruit, raisin-like characteristic to the final whisky. A long maturation period in PX will result in a very dark colour; shorter spells will impart a lighter amber colour.   

Port pipe – one of the largest casks used in whisky maturation, the Port pipe is made from thick staves of European oak and has a capacity of 650 litres. As the name suggests, it is seasoned with Port.  

Pot still – the copper apparatus used to batch-distil spirits is called a pot still. By law, all Scotch whisky must be produced in a pot still. The main components of a pot still are the pot, swan neck, lyne arm and condenser.  

Proof – the American term used for measuring alcoholic strength. Proof is equal to twice the European alcohol percentage, ie 120 proof is 60% alcohol (abv). 

Puncheon – 500-litre capacity casks are called puncheons. Short, squat puncheon casks made from American oak staves are commonly used in the rum industry. Similar shape puncheons, made from thinner staves of European oak, are typically used in the Sherry industry and later in the Scotch whisky industry.  

Unpeated malt – malted barley that has been dried (kilned) over fires that are not fuelled by peat is called unpeated malt. This can be used to produce an unpeated malt whisky. 

Quarter cask – can either refer to a quarter of a butt or a quarter of an American Standard Barrel, equivalent to 125 or 50 litres, respectively. These smaller casks hasten the time it takes the oak to impart the desired characteristics on the liquid as there is greater spirit-to-cask contact.   

Quercus alba – a species of white oak grown in America and, less commonly, Spain. Quercus alba – commonly known as American oak – is a popular choice with coopers for its tight-grained structure and with distillers for the vanilla, toffee and coconut characteristics it imparts. American white oak casks have proliferated the whisky market since the early 20th century as the popularity of American whiskey increased and supply of European oak (Sherry) casks stalled. By law, Bourbon must be matured in new, charred American oak barrels. Barrels made from quercus alba typically impart vanilla and caramel characteristics on the final whisky profile. American oak is sometimes used for wine (especially certain American icons like Ridge Vineyards’ Montebello), however French oak is generally favoured for its more subtle influence.  

Quercus robur – oak native to France, and the oak used most often for wine maturation. The vast majority of Scotch whisky barrels used to be made from quercus robur, more commonly known as European oak. The highest quality examples go through a two-stage process of being seasoned and kiln-dried or air-dried for up to five years. Traditionally, European oak barrels are toasted under a gentle flame for up to 15 minutes which imparts a spicy, clove characteristic to the final whisky. 

Racked warehouse – a modern warehouse design that is considerably larger than the traditional dunnage warehouse. Casks and barrels are stored on their sides, up to 12 casks in height – this is advantageous as they can easily be transported by machine. Racked warehouses normally have walls made from brick or concrete and a thin roof. The average temperature in a racked warehouse is similar to a dunnage warehouse but humidity tends to be lower due to the concrete floors (dunnage warehouses have earthen floors). Seasonal temperatures, however, are more varied. For these reasons, whisky can sometimes mature slightly faster in racked warehouses.  

Refill barrels – a cask that has previously held alcohol is called a refill barrel. These vessels are slightly less “active” than first-fill casks and allow the spirit to dominate. Refill barrels are commonly used in Scotch whisky maturation.  

Reflux – during the distillation process, alcohol and congeners separate from water when heat is applied (directly or indirectly) to the still. In Scotch whisky-making, vapours travel up the pot still and condense in a piece of apparatus known as the condenser, where they are collected before being re-distilled in the spirit still. This important balance of copper contact and condensing is known as reflux. The size and shape of the copper pot still and the angle of the lyne arm affect the level of reflux. To create a lighter spirit, producers will increase the amount of reflux. The opposite is true if a heavier spirit is desired.  

Regauge – the process of calculating a cask’s contents is called regauging. During regauging, the cask is weighed, emptied and weighed again before the alcohol strength is measured. This process is crucial to determine how much liquid has been lost to evaporation (known affectionately as the angel’s share), and helps the cask owner understatnd how the spirit is maturing.   

Rejuvenation – casks can only be used a finite number of times before they lose their efficacy. They can be rejuvenated by removing the old charcoal layer and being re-charred. STR (Shaved, Tasted and Re-Charred) is one of the most popular processes for rejuvenating casks. STR was pioneered by the late Dr Jim Swan. Simply, the process of shaving, toasting and re-charring casks removes the unwanted acids, breaks down the lignin structure of the wood to release wood-related compounds (including the desirable vanillin and caramel notes), and imparts a nice, sweet character to the spirit.  

RLA – re-gauged litres of alcohol, or RLA, is the accurate amount of pure alcohol within the cask. This is an important figure when determining the amount of duty that will need to be paid when it comes to bottling a cask. 

Rye whiskey – an American whiskey made from a mash bill of at least 51% rye. The remaining 49% can be any grain – often corn or barley – including rye. Rye whiskey, like Bourbon, must be matured in new (virgin), charred American oak barrels. Straight rye whiskey must be aged for a minimum of two years. Rye whiskey is typically spicy with caramel and vanilla characteristics imparted from the new barrel. Rye whiskey can be produced anywhere in the United States of America and must be distilled to a minimum of 40% alcohol (80% proof). 

Saladin box – Saladin boxes are one of the first replacements for distillery floor maltings. They are horizontally shaped and have a spinner that moves across the bed several times each day. This rotation, which was traditionally done by maltsters by hand, enables air to be blown through the barley until it germinates and becomes green malt – at which stages it needs to be transferred to the kiln for the next stage in the whisky making process. 

Shell-and-tube condensers – the modern condenser which has largely replaced the worm tub condenser in Scotch-whisky making. As the name suggests, these are copper shells which contain approximately 100 copper tubes through which cold water flows from the lyne arm during the distillation process. Shell-and-tube condensers typically producer a lighter spirit character.  

Secondary maturation – another name for cask finishing, secondary maturation is the process of removing whisky from the barrel in which it began maturing and placing it into a different cask, normally for a much shorter maturation period. The process, which was pioneered at The Balvenie and Glenmorangie in the 1980s and is now commonplace, can add additional flavour. PX casks are a popular secondary maturation vessel.   

Sherry cask – technically, there is no definition for “Sherry cask” under Scotch whisky regulations. While casks have to be made of oak and hold no more than 700 litres, the rules do not specify how long a cask would have to hold Sherry for the term to be used on the label. In 2015, a Sherry cask seasoning accreditation programme was introduced by the governing body, the Consejo Regulador – before this, there was no guarantee a “Sherry” cask had held wine from the official region known as the Sherry Triangle, located near Jerez de la Frontera. Typically, a Sherry cask will impart clove, tannin and dried fruit characteristics on the final whisky profile.  

Single-cask whisky – as the name suggests, a single-cask whisky has been matured and bottled from a single maturation vessel. Single-cask bottlings are normally highly coveted as they are, by their very nature, limited releases.   

Single grain Scotch whisky – can be produced from grains other than malted barley. The majority of single grain spirit is made from a mashbill with a high percentage of wheat, with a small percent of malted barley. Single grain whisky is usually distilled in a continuous, column still, but it can be distilled in a copper pot still. It must be distilled (at no higher than 94.8% alcohol) and matured in Scotland.

Single malt – single malt whisky is produced from malted barley at a single distillery, hence the use of “single” in the name. Somewhat confusingly, single malts are a blend of whiskies and are not produced from a single barrel – these are known as single-cask whiskies. By law, single malt Scotch whisky must be distilled, matured in oak casks for a minimum three years, and bottled in Scotland.  

Speyside – Speyside is the most densely populated whisky-making region in the world, boasting more than half Scotland’s malt distilleries. The region is located within the Scottish Highlands and wasn’t recognised as a whisky-making region in its own right until relatively recently. Since this change, some distilleries have opted to retain the Highland label despite being located in the Speyside region – the most famous example of which is The Macallan. The region – located in the Moray area in the north-east between Aberdeen and Inverness – takes its name from the river on which many of the most famous distilleries are located. While today the regional style is largely notional, classic Speyside whisky characteristics are green fruit, vanilla and honey. 

Spirit safe – the spirit safe was invented by Septimus Fox in the early 1820s. A few short years later, these padlocked brass containers with glass panes were made mandatory in all distilleries with the introduction of the Excise Act. Until 1983, the exciseman was the only person with a key to the spirit safe to prevent the unsanctioned sale of alcohol. The spirit safe has a number of other uses, including the measurement of the appropriate cuts (heads, hearts and tails) of the distillate.   

Spirit still – used in the second stage of the distillation process. After the first distillation has taken place in the wash still, the low wines (around 25% alcohol) are re-distilled in the spirit still. Some distilleries distil a third time but this is rare in Scotland. After distillation in the spirit still, sometimes referred to as the low wines still, the whisky maker will take a fraction, known as cuts. The heads and tails (foreshots and feints) are returned to the whisky-making process for re-distillation; the hearts are the new-make whisky destined for maturation. 

Spirit receiver – vessel where the new-make spirit is collected after distillation 

Stave – planks of oak that have been dried, seasoned and shaped before being sent to a cooper to make a cask. On average, 30 staves are used per barrel.  

Steeping – the process of soaking grain in water for two to three days before germination can begin  

STR – abbreviation for Shaved, Tasted and Re-Charred. STR is one of the most popular processes for rejuvenating casks that was pioneered by the late Dr Jim Swan. Simply speaking, the process of shaving, toasting and re-charring casks removes the unwanted acids, breaks down the lignin structure of the wood to release wood-related compounds (including the desirable vanillin and caramel notes), and imparts a nice, sweet character to the spirit. STR was born out of necessity in 2010 when shortages of refill casks began to cripple the industry.

Straight Bourbon – an American whiskey made from a minimum 51% corn that has been matured for at least two years in new (virgin), charred American oak barrels. By law, straight Bourbon must be produced in the United States and bottled at 80 proof (40% alcohol) or higher.  

Swan neck – a copper pipe from the pot still which narrows into the lyne arm where vapours condense during the distillation process  

Tennessee whiskey – a whiskey produced in the American state of Tennessee. By law, Tennessee whiskey must be made from a mashbill of at least 51% corn. It must also undergo a process which involves filtering the new-make spirit through sugar maple charcoal before maturation known as the Lincoln County Process. Although there is no minimum maturation requirement for Tennessee whiskey, there is for “Straight Tennessee whiskey” (two years) and “Bottled-in-bond Tennessee whiskey” (at least four years). Tennessee whiskey must be bottled at a minimum 80 proof (40% alcohol). Jack Daniel’s is the most famous example of this whiskey style.  

Toasting – all oak casks are toasted. While constructing the casks, the wooden planks – known as staves – are manipulated into shape over fire. The application of fire breaks down the structure of the wood and enables more interaction with the new-make whisky. The process of toasting oak casks is less intense than charring. There are two toasting levels which are measured as lighter and heavier. A lighter toast will impart nutty and vanilla characteristics, whereas a heavier toast will typically result in more caramel notes. By law, Bourbon casks are toasted and then charred, whereas Sherry and wine casks are typically only ever toasted. 

Uisge beatha – from the Gaelic meaning the “water of life”  

Vatted malt – or pure malt, is the original name for blended malt Scotch whisky. It is produced by blending malt whiskies from different distilleries.     

Virgin oak – another term for new barrels that haven’t previously been used. By law, Bourbon and rye whiskey must be matured in virgin, charred oak barrels. 

Warehouse – where whisky casks are stored during the maturation process. There are several different types of warehouses, from the traditional dunnage to the more common racked.  

Wash – term can be used to refer to the wort as soon as yeast is added and fermentation has begun; it can also be used to refer to the liquid post-fermentation.

Wash still – the wash still is the first copper pot still used in the traditional Scotch whisky-making process. It is named after the wash (fermented liquid). Traditionally, the wash still was direct-fired (with a flame) but today it is more commonly heated by steam coils, known as indirect-fired. As the wash is heated, vapours travel up the swan neck, through the (shell-and-tube or worm tub) condenser. The resulting distillate, known as low wines, are collected and re-distilled in the spirit still.  

Washback – the tall, circular vessels which are used to ferment wort in brewing and distilling are called washbacks. Traditionally made from timber, these can be made from stainless steel and vary in size and shape. Washbacks are filled with the sugary mixture known as wort to the two-third mark and yeast is added to start the all-important fermentation process. The industry average is approximately 60 hours but some producers have been known to exceed 100-hour fermentation times which results in a typically fruitier profile. 

Whiskey – the common spelling for whisky which has been produced in America or Ireland   

Whisky – the common spelling for most whisky, including those produced in Scotland, Japan and Canada  

Worm tub condensers – the unusually named piece of apparatus which cools vapours and converts it into liquid, invented in the 19th century. The traditional worm tub condenser is coiled, like a worm, and runs from the lyne arm into a tube filled with cold water which usually sits outside the distillery. Due to their expense and inefficiency, many distilleries replaced worm tubs with the shell-and-tube condenser. Some distilleries still use worm tub condensers to produce a heavier style of whisky.  

Wort – unmalted and malted grain that has been mashed with warm water is called wort. This liquid, which needs to be cooled, contains all the sugars of the malt that is vital for fermentation.    

WOWGER – Warehousekeepers and Owners of Warehoused Goods Regulations, or WOWGER for short, is legislation that enforces the registration of ownership of casks – and other goods – detailing procedures when transferring whisky from one bonded warehouse to another.  

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