Pure pot still whiskey is a type of whiskey which contains only "pot still whiskey". It is unique to Ireland.

Traditionally "pot still whiskey" was made from a mixture of malted and unmalted barley, distilled in a pot still as opposed to a Coffey still. The ratio of unmalted to malted barley can vary, but there tends to be more unmalted barley in a pure pot still whiskey blend. For example, the various Jameson blends have a 60:40 (unmalted:malted) ratio.

Under modern Irish law, any whiskey distilled in a pot still can be termed "pot still whiskey". Therefore, it is not legally necessary for a distiller to add unmalted barley to his or her grain mix. Some whiskeys produced by the Cooley Distillery break from tradition and do not use unmalted grain. Thus, they are actually single malt whiskeys, but can be legally labelled "pot still whiskey" if the distiller so chooses. The majority of "pot still whiskeys" conform to the traditional definition.

POT STILL
A pot still is a type of still used in distilling

spirits such as whisky or brandy. Heat is applied directly to the pot in which the mash (in the case of whisky) or wine (in the case of Cognac) is contained. This is called a batch distillation, (as opposed to a continuous distillation).

At sea level, water boils at 212 degrees Fahrenheit but alcohol boils at 188 degrees Fahrenheit. Therefore, in the distilling process, while there is still alcohol in the mash, the vapour is richer in alcohol than the liquid itself. When this vapour is condensed, the resulting liquid therefore contains more alcohol. In the pot still, the alcohol and water vapour, combined with vapours of the multitude of aroma components such as esters, alcohols that give the mash or wine its aroma, evaporate and flow from the still through the condensing coil. There they condense to the first distillation liquid, the so-called 'low wines', with a strength of about 25-35% alcohol by volume, which then flows into a second still below. It is then distilled a second time to produce the colourless spirit, collected at about 70% alcohol by volume. Maturation in an oak aging barrel typically causes the brown color to develop over time.

The modern pot still is a descendant of the alembic, a distillation device invented around the eighth century AD for use in alchemy.

The largest pot still in the world is in the Old Midleton Distillery, Co. Cork Ireland. It has a capacity of 31,618 gallons (approximately 140,000 litres). It is no longer in use however.