Is an older whisky always better?

The age on a whisky label is the maturation time of the youngest whisky in the bottle, expressed in years.

If the bottle also contains older whisky, it may not count towards the figure. Regulation 12 of the Scotch Whisky Regulations 2009 lays this down and refers to the European rule that an age statement always relates to the youngest component.

The number therefore tells how long the liquid has lain on wood. It says nothing about the cask in which that happened, the strength at which it was bottled or the flavour.

A small cask gives much more wood surface per litre than a large cask, so that substances from the oak end up in the whisky faster.

Check the maths. For casks of the same shape, the surface area per litre rises with the cube root of the difference in volume. A cask of 125 litres therefore has roughly 59 percent more wood surface per litre than a cask of 500 litres. The legal upper limit is 700 litres.

In a small, fresh cask, uptake therefore goes fast. After a few years, the share of wood compounds can already climb high. That is not a matter of young or old, but of how much wood there was per litre of liquid.

A cask that has been filled several times gives off less and less, so after many years little colour, aroma and flavour is added.

The Scotch Whisky Association allows, besides new oak, casks that have previously held wine, beer or spirits. Such casks last several fills. With each subsequent fill, there is less soluble material in the wood than with the previous one.

If a whisky lies a long time in such an exhausted cask, the years add up without the cask offering much in return. Meanwhile liquid evaporates from the cask every year. More time then yields no extra flavour.

No, whisky does not mature any further once it is in glass: a 12-year-old whisky stays 12 years old, even after decades in the cupboard.

Maturation is the interplay between liquid and wood. In a closed bottle there is no wood left that anything can come out of and no cask wall through which anything evaporates. The Scotch Whisky Association states this in so many words.

An older bottling can certainly differ from a newer one of the same whisky, because production has changed in the meantime. That is something different from further maturation.

Look at the bottling strength, the cask type and whether caramel has been added; that information tells you more about the glass than a year does.

The bottling strength is always on the label. The legal minimum is 40 percent and cask strength is well above that. With Scotch, the new make according to the Scotch Whisky Association usually goes into cask at around 63.5 percent.

Caramel E 150a is the only additive allowed in whisky, and only to correct the colour. Colour is therefore no measure of age. Ask in the shop about the cask type and the fill number; that tells you more than the number on the front.