What is single cask whisky?

All the whisky in the bottle comes from one cask. Nothing has been blended in from other casks, not even to even out the profile or the percentage.

In a regular bottling, tens to hundreds of casks are combined so that each batch resembles the previous one. With single cask, that step falls away. What the cask gave is what is in the bottle.

The label therefore almost always carries a cask number, and often also the year of filling and the year of bottling.

A cask is finite. Once it is empty, there is no second batch of the same whisky, so every bottle gets a serial number out of a fixed total.

The numbering makes it possible to trace how large the bottling was and which bottle you are holding. With a bottling from several casks that makes little sense, because it can be repeated later.

Bottlers often also state the cask type, for example ex-bourbon or ex-sherry, and the number of bottles the cask has yielded.

The yield depends on the cask size and maturation time. A bourbon cask of around 200 liters usually gives over 200 bottles after ten years of maturation.

Common sizes are the barrel of about 200 litres, the hogshead of 250 litres and the sherry butt of 500 litres. A quarter cask holds 125 litres, a puncheon 500 to 550 litres. For Scotch, 700 litres is the upper limit.

Evaporation makes that number fall year after year. A cask that has lain for thirty years yields considerably less than the same cask after ten years. At cask strength, moreover, fewer bottles come out than when water is added.

Single malt refers to a single distillery, single cask to a single cask. Small batch means a small blend of a handful of casks, without a fixed number.

Single Malt Scotch Whisky is in fact legally defined: distilled in pot stills at a single distillery, from water and malted barley, without other grains. A single malt almost always consists of several casks from that same distillery.

Small batch has no legal definition and no lower or upper limit. One bottler calls four casks small batch, another forty.

No. The Scotch Whisky Regulations 2009 recognise five categories of Scotch, and single cask is not among them. A definition of the term is not in the law.

Those five categories are Single Malt, Single Grain, Blended Malt, Blended Grain and Blended Scotch Whisky. Words such as single cask, cask strength and small batch are industry usage, not protected designations.

In practice almost everyone sticks to it, and the general rules against misleading labelling still apply. Anyone who wants certainty should look at the cask number and the number of bottles on the label, not at the term alone.