Distillation

Distillation is a method of separating liquids with different boiling points. In our situation we want to extract (distill) alcohol away from a fermented liquid. Ethanol (alcohol) has a boiling point of 78.37 degrees Celsius, which means that it can be removed from a liquid whose boiling point is higher (e.g. 100 degrees).

Interestingly, alcohol has a melting point of -114 degrees Celsius, which means that you also have the option of going the other way, i.e. freezing into a distillate.

When the alcohol reaches boiling point it evaporates and this vapor is cooled to condense and the condensed liquid is collected in a separate container.

Pot still

Pot-distillation is clearly the simplest way in terms of setup, yet the one that gives the most complex result. Distillation takes place in large copper kettles in which the fermented liquid is heated and diverted by the condenser to another container. Pot-distilled spirit must in some cases go through the apparatus 4 times to guarantee a satisfactory product.

The reason why this method gives the most complex result is because the product is not “pure”, meaning the distillate retains a lot of flavor nuances from the fermented crop. Examples of pot-distilled spirits are dark rum and whiskey.

The English version is called “pot still” and, like so many others, consists of copper, as copper is so excellent at handling and distributing the heat. In Scotland a boiler can hold 20-50,000 litres, and in Ireland it is 100-150,000 litres. The French version of a pot still is called “Alambic Charentaise”, where the biggest difference compared to the English one is that the French one can only contain 12,000 litres.

The Carterhead still

This still is a pot still with a single quirk that makes it primarily used for the production of gin. This type of still was invented in the 19th century by the two Carter brothers, who had originally been employed by Aeneas Coffey (see column still). After learning about distillation, they left Coffey to create their own business, designing and producing unique stills. Originally, the Carterhead still was developed to rectify raw alcohol produced by Coffey so that it became alcohol suitable for the production of gin and vodka. The still usually has a capacity of 3,000 litres.

The Carterhead still is a pot still, where a basket is placed between the pot itself and the condenser, so that alcohol vapors will pass through the basket before it is condensed and collected. How this change on the distiller changes what you get can be read on the gin page under the production method flavored gin.

Column still

Aeneas Coffey further developed the ideas of Sir Anthony Perrier and Robert Stein and in 1830 obtained a patent for his column still. A column still is a still with two columns that can distill continuously.

One way to make a column still is, as in the picture here on the right, where the liquid to be distilled enters at no. 1. The liquid is led over into the first column, which is called an “analyzer”. Steam is introduced into the bottom of the analyzer (no. 2), which heats the liquid. What does not evaporate away will slowly settle down through the layers and be led out the bottom (no. 3) of the still. What evaporates will be led over to column 2 (no. 4), which is called a “rectifier”. In the rectifier, the liquid that does not evaporate will fall to the bottom and be returned (no. 5) in the first column. At the top of the second column, the steam is condensed (no. 7) and directed into a container (no. 6).

In addition to the water vapors that are fed in (no. 2), the columns themselves are also heated. At the bottom, the temperature will be 100-110 degrees Celsius, but only 80 degrees Celsius at the top. This, together with the many perforated layers up through the column, means that only the alcohol vapors leave the column. The many layers in the column cause the vapors to condense and have to evaporate again to get to the next layer.

The advantage of a column still is that you can achieve a very high alcohol percentage (up to 96%), which gives a much cleaner product, but also gives less flavor from the original product. Water is added to the distilled liquid after distillation to achieve the correct alcohol percentage.
Gin is a bit special here as you take the 96% neutral spirit and add flavor to it afterwards. Specifically, how the different types of spirits are fermented and distilled can be read on each of their pages.

The head, the heart and the tail

The result of any distillation is divided into three separate parts in the following order: the head, the heart and the tail. The best and desired portion of the distillation is obtained from the heart.

The transition between the three parts of the distillate is up to the distiller to decide. The art lies in knowing when to start collecting the heart and when to stop again. Experienced distillers use their senses to determine where the transitions are. The head can be tasted and smelled. It usually has a very sharp taste and is foul-smelling as it contains a combination of acetone, methyl alcohol, methanol and ethyl acetate. The heart of the distillation (the ethanol) should be completely transparent and odorless. The tail contains a large amount of higher boiling alcohol compounds such as furfuryl. These compounds can ruin the taste of the alcohol if you collect for too long. The transition point to the tail can be identified by the taste, smell and milky cloudiness of the distillate. The tail is usually saved and included in the next distillation, as it still contains some ethanol.

After the distillation, individual types of spirits are aged to mature them. You can read about it here: aging of spirits. Otherwise, you can click on the different types of spirits under the menu item “Spirits”, where production is more specifically explained in relation to the given spirit.