Whisky casks and what wood does


When it comes off the still, whisky is around 60-70% alcohol and as clear as water. It takes all of its subsequent colour from the casks it’s matured in, as well as much of its flavour. As it ages, it also evaporates and loses strength – the whisky lost to evaporation is known as the angel’s share. Unlike wine, whisky does not continue ageing once inside the bottle.

There are two main types of cask distillers use, the most popular being ex-Bourbon casks from America which are in good supply as US Bourbon rules mean they can only use their barrels once.

Whisky matured in a  bourbon cask will traditionally have a lighter, yellow gold colour. The key flavours bourbon casks give a malt are the sweeter light notes like caramel and vanilla. Generally speaking, bourbon matured whiskies are the most traditional whisky flavours.

Sherry casks are the second most used casks in whisky maturing. With sherry drinking in the UK having plummeted, these normally come from Spain making them more costly to use.

Sherry casks produce the dark brown colours in whisky, and also strong, rich flavours of dark fruits, Christmas pudding, and (unsurprisingly), sherry, among others.

Because sherry casks can have such strong effects, many sherried whiskies are only ‘finished’ in them for a year or two after spending their formative years in the mellower bourbon casks. It takes a very robust new make spirit and a seasoned distillery to produce an aged, fully-sherried whisky.

Some of the more progressive distilleries like Bruichladdich and Glenmorangie are also experimenting with wine casks and even rum casks with some great results. Very much in the minority these are well worth searching out if you’re well into your wood. As it were.