The Scotch Whisky Cask Glossary

Unlock the secrets behind Scotch Whisky Casks with this definitive guide! This article explores various finishes, cask sizes, and materials integral to the Scotch Whisky making process. Discover references to finished products that exemplify these processes and finishes. Have any insights to add? Share your thoughts!

What’s the difference between a PX and an Olo?

What’s a barrique, and why do I have to share my whisky with the angels?

What’s a butt… and what the hell is a BUNG HOLE?

If you’re new to whisky, there’s a mystifying world of ‘casks’ which awaits beyond the reach of the supermarket dram.

Whisky isn’t just about the spirit thats in the bottle, but you’d be amazed that the size of the cask, and the type of wood it’s made from has an influence!

American Oak - An oak native to the northern hemispheric climbs of North America. The Quercus Alba is most commonly used to mature Bourbon whiskey, but regulations in the USA state that the casks can only be used once. They are often shipped over to cooperages in Scotland and repurposed for Scotch by a cooper.

ASB - American Standard Barrel. This is a 200 litre cask made from Quercus Alba.

Angel’s Share - The Angel’s Share is natural spirit evaporation from the cask as it matures. There have been experiments in how to avoid cask maturation loss. In my opinion, if we prevent cask maturation loss, then it devalues the whisky and shits on the traditional process, but it does, however allow more people to enjoy the spirit... so it's a double edged sword!

Barrique - A cask used in wine and brandy which we can use after the wine and spirit makers are finished with it… and the results are great. Usually about 225 liters, or 300 for Cognac producers.

Blood Tub - This is a 30-50 litre cask.

Bung - A bung is a rubber or cork stopper for a cask. It can be wedged in safely with a Bung Cloth, taken out of the Bung Hole with a Bung Extractor. The bung extractor looks like a corkscrew with a hammer attached to it. It’s one reason to never piss off a warehouseman. Bungs in Scotland have to be wooden. Most are made of Poplar wood. Cork and Rubber bungs were outlawed in Scotland a few decades ago.

Butt - Two great whisky innuendo words next door to each other. What else do you want? A butt is a 500 litre cask. ‘Filling your butt full of whisky’ never sounded so thrilling!

Charr - This is the level in which the cask is burnt to. The charring acts as a filter for the spirit before it comes into contact with the oak underneath.

Chinkapin - A type of American white oak. Quercus Muehlenbergii. (Kwerk-uss Moo-Ellen-Berg-y). You’ll rarely see this used in full maturation but it is used in finishing. (Found here)

Copper Dog - The Copper Dog is a thin cylindrical tube similar to a (test tube) attached to a chain with a cork in the top. It’s dipped into a cask to remove a small quantity of whisky for sampling by warehousemen, master blenders and other staff. Historically, they were known as man’s best friend, as distillery workers would secrete a sample away under their trousers to enjoy with supper.

Dunnage Warehouse - This is where the whisky matures. When you picture a warehouse full of whisky, this is what you’re picturing. The casks are stacked one on top of the other, and apart from the walkway, the dunnage floor is made up of chuckies, (aggregate stone) to stop casks from rolling, should they be knocked from the pile. It’s an old form of Damage Control!

European Oak - Quercus Robur. (Kwerk-uss Roe-burr.) This is a type of wood which gives more of a lighter, woodier note on whiskies than what American Oak will.

First Fill - Also known as Virgin Oak - this does exactly what it says on the tin (or barrel!) it’s never been used before. It should present a clean crisp flavour of sour apple sweeties, or sweet orchard fruits depending on your palate!

Finish - Finish is the term used when whisky is moved from is 'Maturation' cask into a cask where it will finish it's maturation. This element of the maturation can be what sets out a whisky from its competitors. Here I'm going to try and decipher the casks that I've come across and explain them as best as possible.

Wood Finish - American Oak, Japanese Oak, Hungarian Oak, Scottish Oak, French Oak - These oak finishes will present spices, vanilla and sweet oak in the notes. A great example of this is GlenAllachie Hungarian Virgin Oak 7YO

Port Finish - Usually called a Pipe or Barrique, usually French Oak. Usually used for Port from Portugal. The 220 litres for a port barrique and 600 litres for a port pipe will give off berry fruits, redcurrants, raspberries, cranberries and the like, with dried fruit notes also. Try anything finished in a Douro Cask or Claxton's for the Stirk Brothers, Ardmore 9YO Tawny Port.

Wine Finish - Common cask names are a barrel or barrique are typically made of French Oak local to wine regions like Bordeaux, Cote du Rhone, Alsace, Loire Valley, Burgundy in France, Montepulciano D'Abruzzo, Tuscany, Piedmontese, Veneto, Puglia in Italy, Reisling, Hessische Berstra?e, Rheingau in Germany, the list is endless... and this is a whisky blog! The typical flavours will vary according to the wine. Bordeaux gives Red berries, cherries and plums. Try some of the Isle of Raasay Single Malt Cask Strength 2024. It's Ex-Bordeaux, Ex-Rye and Virgin Chinkapin Oak. The normal Raasay was absolutely phenomenal stuff, and the cask strength just gives more ABV for your nose to explore more key characteristics at 61.3%ABV.

Madeira Finish - A portuguesa oak drum of up to 650L which presents sweet fruits, figs and spices. A great example of this finish is Glencadam 15 Year Old 2008 Mad Cask Finish

Rum Finish - Usually American oak with Caribbean rum seasoned staves. It'll give flavours of Molasses, Vanilla, Tropical fruits such as mango, banana, chocolate. It's a great finish tbf. Popular example of this finish would be Glen Scotia Double Cask Rum Finish.

Beer Finish - Something you don't see often. Glenfiddich tried it with the IPA finish stuff and it - for me - was lacklustre. I might have been in the wrong place, the wrong mood, so if you work for Fiddich, don't come with the pitchforks, I'll try it again and I might like it more! Usually an Ex-American Oak up to 200L will present sweetness with heavy, heavy malt flavour, yeasty, hoppy, creamy. To me, if someone did a whisky Jaegerbomb into your pint, this is what it tastes like. Not my bag unfortunately. Jameson Caskmates is another popular example of this.

Sherry Finish - These finishes deserve their own bold headliner and italics! Sherry finishes are, in my opinion, the greatest finishes that lend themselves really well to robust Whiskies from Scotland. There are multitudes of sherry finish whiskies. 'Multitudes' is probably an understatement to be fair, but it's easy to taste why the sherry finish is one of grandeur. Try the Meikle Tòir Sherry.

Here is a breakdown of Popular Sherries

PX - Pedro Ximénez (Him-ay-nez (really make the H quite harsh in your best Spanish accent!) Sherry is made from grapes of the same name which undergo a traditional process called 'sunning.' Basically, the grapes are air dried and turn to raisins. The flavour is more concentrated and the grapes develop a must, with an exceptionally high concentration of sugar. It's the sweetest wine in the world. Try soaking Strawberries in PX as part of a boozy dessert.

Olo - Olorosso (All-O-Ross-O) means 'scented' in English. It's a variety of sherry from Jerez (Her-reth (again make the H really quite harsh!). Its main feature is oxidative ageing, like in the solera system. It's normally darker than Amontilladoand it's usually quite dark and nutty.

AMT - Amontillado (Ah-Mon-Tee-Ya-Dough) is a unique wine produced from the complete fermentation of Palomino grape must. Amontillado has a really delicate bouquet. Hazelnut and dark tobacco are two standout characteristics. If you can get yourself some Glen Scotia 12 year old Amontillado Cask Finish, you are in for an ethereal surprise.

Fin. - Fino (Fee-No) is a Dry White wine also made from the Palomino Grape. Similar to Manzanilla, is aged under a layer of yeasts. It has a short delicate smell of dry toasted nuts and wild herbs. It has a really pleasant aftertaste, similar to Almond croissants for me! Fino has an ability to stimulate taste buds and due to that characteristic, is great as an apertif. It's also quite useful in the kitchen when making white sauce for chicken or light vegetables like Cauliflower.

Manz. - Manzanilla (Man-Za-Knee-Ya) is a dry white wine aged for at least two years under a layer of flor yeast. Technically it's identical to Fino, but the only thing that separates the two are the location in which they are produced. Manzanilla can only be produced and matured in Sanlúcar de Barrameda which is closer to the sea than Jerez.

PC. - Palo Cortado (Pal-Low Court-Tah-Dough) is a great little thing. It's a deep wine with the bouquet of Amontillado with the body and palate of an Olorosso. Orange zest, tobacco and leather, buttery and smooth. You should maybe try some sherries, if you can get hold of some from a local retailer. This will really help you file down to what sort of finish you might like on a whisky!

Mos. - Moscatel (Moss-Kah-Tell) is a type of wine made from Muscat grapes. The term is widely used in the USA to refer to a fortified wine made from grapes, rather than just any old wine made from these grapes.

Gravity Cask - A gravity cask is a cask which has two different ends. One might have heavy charr, one might be Peated… these specifics can be discussed with a cooperage when they make up the cask to order.

Hogshead - A 230-250 litre cask.

Limousin Oak - (Le-moo-zan) This particular type of cask is from the Departement in France called ‘Limousin.’ The region is a great producer of Cognac (a variety of brandy. (Brandy is Wine Distilled twice or more and has an end product which harbours between 30-60%ABV ) and Armagnac. (Wine that is distilled once.)

Mizunara Oak - This is a species of Oak that is found in Japan and North East Asia. Known as Quercus Mongolia Crispula, this oak is really rare, and is usually used for finishing rather than maturation.

Octave Cask - A 50 Litre Cask.

Palletised Warehouse - A warehouse where the casks are stood up on end and stored on pallets. The pallets are then stacked up on top of each other.

Pipe - This is not a pipe, but instead a cask used for maturing port, round about 350+ liters in size. Sometimes up to 500 liters.

Quarter Cask - a 125 litre cask. One quarter of a butt. It has been said that a quarter cask is also 50 litres in size. This is one quarter of the size of an American Standard Barrel

Racked Warehouse - Basically Costco for whisky… Racks upon racks of casks from floor to ceiling.

Reed - A piece of material used to seal the cask head and tail. No glue is used in traditional cask making. It’s a real artisan tradition.

Refill Cask - A refill cask is a cask that's been used to store spirit at least twice. First as a virgin oak, then as a first fill, then being used again after this.

Seasoned Cask - A seasoned cask is a cask that has had liquid in it previously. The liquid might have been used before to season the wood with a particular characteristic.

Seasoning - The process of drying a piece of wood to make it more suitable for use in building casks.

STR - (Shave, Toast, Recharr.) - Small amounts of the inside of the stave are shaved off to reveal 'active wood' (wood which is instrumental in the flavour profile characterisation of the spirit.) It's then toasted and recharred.

Solera System - This is an absolutely fascinating process. Picture a pyramid type of arrangement of casks in a dunnage warehouse. Whisky is filled into the top barrel. There is then a filtration system that works whereby the top cask liquid slowly flows through all the casks until it reaches the end cask. The end cask may be the third cask, which would take around about three years from the first cask to filter through to the third, but the pyramid may be of about thirty casks in some vineyards. (which would mean that it takes thirty years to filter all the way to the last cask!)

Stave - One of the long pieces of wood which make up the cask.

Toast - The process of heating the staves of the cask activating the flavour compounds within, and also helping them to bend into shape.

Tun - A large vat used for marrying/blending casks.

Valinch - A long copper tube used for extracting whisky from the cask. The tube is inserted into the cask and then a thumb is placed over the top end of the Valinch. This allows the user to pull whisky directly from the cask to transfer to a glass. It's similar to what you'll see a barkeeper doing when they've mixed a cocktail to see that they've got the mix right.

Virgin Oak - Oak that hasn't been used to mature any spirit, yet...