In world of whisky distillers proudly inform you of cask used to mature its whiskys, they do this for  a reason, mainly as the base cask provides a indicator to the flavour profile. We here at whiskys.co.uk want to help you determine so of these terms and phases you often see on your bottles. 

Cask Creation:

A cask life start is of the wood selection most traditionally oak is selected. The wood is then cut, angled and planed to create staves (long vertical plank in a intricate system of beams to create a item) are joined together to create the cask body with smaller pieces to create the end pieces. 

Cask maker then using steel hoops temporarily band the cask together to create shape and before attaching the ends of the cask, the interior of the cask must be set alight for a few seconds. The charring of cask removes any unwanted flavours from the wood while creating a layer for the spirit to react with. the ends are attached  along with permanent hoops that help the cask to hold shape then is checked for leaks with water. 

Casks can come in several sizes here is a list in volume, most traditionally the standard barrel is used, followed by hogsheads and butts. The size of cask can affect maturation based on the spirit to wood ratio, menaing bigger cask longer maturation time. 

 • Quarter Cask (45-50 litres)
• American Standard Barrel (190-200 litres)
• Hogshead (225-250 litres)
• Barrique (250-300 litres)
• Puncheon (450-500 litres)
• Butt (475-500 litres)
• Machine Puncheon (500 litres)
• Port Pipe (550-650 litres)
• Drum (600-650 litres)

Cask Selection 

Most traditionally whisky is matured in ex bourbon casks, which unlocks flavours for the spirit, bourbon has to be matured for a minimum of 3 years in cask before being able to be classed correctly. Other types of spirit can be matured in cask before whisky to create a new and unique flavour, some examples are sherry, rum and red wine casks. here a few example of what base cask flavours can be unlocked in whisky.

Bourbon Casks:  Vanilla, sweet creamy and Caramel. 

Sherry: Dried Fruits, Rich, dark chocolate, and Coffee. 

Rum: Bananas, Toffee, Tropical Fruits and Molases.

Red Wine: Dry, Fruity notes.

The Sherry and Bourbon casks are the most commonly used, more and more distillers have started experimenting with Rum casks and red wine ones tend to be used for limited releases. 

Cask can be reused over and over again in whisky maturation, repeated use of cask can add complexity to a cask as it picks up flavour from the the previous fill. Some of terms you will hear is First Fill, Refill,  and Ex-Islay.

First Fill: Had previously never held whisky before in the cask so all flavour comes from the bourbon and wood. 

Refill: Previously held whisky for maturation, often from same distillers.

Ex-Islay: a cask that previously held whisky from a Islay whisky, while the current whisky may not be peated in the traditional sense, can add elements of peaty flavour to whisky of smoke and peat. 

 Hopefully this article has helped explain some of basics of casks used in whisky maturation and why it can be the key factor in flavour profiles of the spirit.