Basic theory of distilling

Getting started with distilling

When you have a saucepan of water on the stove, you will see condensed drops on the inside against the cold lid. Try it: they taste like … water. Nothing special. Now suppose you are boiling wine in that same saucepan, and you taste the condensed drops – you will find that they still taste a little like wine, but mostly very much like alcohol. Congratulations, you’ve discovered distilling. A few thousand years too late to apply for a patent, but still very clever.

Distillation is a technique for separating substances in a solution by means of evaporation. In our case, that solution is an alcoholic drink, and those substances are mostly water and alcohol. The trick is in the difference in boiling points (or vapour points) of these substances. Alcohol at boils at around 78 °C, while water, as you know, does not evaporate until it gets to 100 °C. If you gently heat a mixture of water and alcohol, such as wine like in the example above, the alcohol will initially evaporate slightly more than the water and the vapour will contain more alcohol than the original mixture. By removing the vapour and then condensing it, you separate the alcohol from the water: distillation. This method is also used to make petrol from petroleum, for example. Please don’t try the latter with a saucepan on the stove, nor taste it :+) By distilling you can roughly separate the different substances, but this is not a precise separation. If you want a more precise separation, you must repeat the distillation. We usually do this (at least) twice: first distillation and second distillation.

Whisky still | Distillation Supplies

The First Distillation

The first distillation is mainly intended to extract all the alcohol from your mash (base spirit) so you can discard the remainder. A 10- or 20-litre bucket, or those fifty bottles of sour wine, take up a lot of space in your kitchen. Assuming a basic drink of about 15 percent, you can expect an alcohol percentage of around 35% after the first distillation. The rest is water. When you taste the result, you can imagine the naming: you unmistakably recognise the fundamentals of a cognac or whisky, but it is still coarse, unrefined. Let’s say: rough. This is because wine, sugar water or whatever you want to distil, contains more than just water and alcohol. It also contains other volatiles created during fermentation. And not just a handful, but thousands. Fortunately, or every drink would taste like vodka. You want some of those substances in your distillate. They provide flavour and aroma. The difference between whisky and cognac is largely in the different basic products. We prefer not to add other substances because they don’t taste good, cause a hangover or are bad for your health. The most important substances are methanol that drips from your still at the beginning of your distillation process and the so-called ‘fusel’ or ‘fusel oil’. This is a collective name for a series of higher alcohols with complicated names that present themselves at the end of the distillation process.

The Second Distillation

The second distillation produces the potable spirit. Because the unwanted parts of the distillate present themselves at the beginning and end respectively, it allows you to separate them from what we’re really interested in: the alcohol. We do this during the second distillation, where the low wine from the first distillation is distilled again but make a distinction between the unwanted heads and tails of the desired hearts. This second distillation produces the potable spirit. The correct separation of these ‘fractions’, not too soon and not too late, is where skill is required. Pure alcohol is just boring vodka, and minimal amounts of the tails particularly, add flavour to your distillate. The result of this second distillation is usually an alcohol percentage of around 70 to 80%. You can repeat this trick. The higher the final alcohol content, the purer and more refined your distillate, until it eventually just becomes tasteless. Vodka, for example, is distilled up to 90-95%, and then often also stripped of all taste by using carbon, for example, while cognac, for example, contains around 60-80%. You will notice that these are not the percentages you see on your store-bought bottles of spirit (unless you live in Russia). Distilled alcohol is almost always diluted with water after maturing (see below) but before it is bottled.

Maturing your distillate

Fresh from the still, your distillate is not yet what it can be. A distillate must mature. There is a reason for paying more for a bottle of twenty-year-old whisky than for a three-year-old whisky. Maturing occurs at approximately 55-65%, not at the 35% that you are used to drinking. It isn’t diluted until just before bottling. Incidentally, maturing does not have to be done on wood at all, nor does it need to take twenty years. Most white drinks such as vodka, gin and eau de vie only mature for a few weeks in glass or oak wooden barrels. Plenty of time for substances to interact and form new combinations. ‘Brown’ drinks such as whisky, cognac and calvados are generally aged in wood. Before bottling spirits, they are diluted to bottle strength, often around 35-40%. In addition, the drink can be pimped, for example by adding caramel for a nice brown colour or by adding a little sugar.

Oak woorden barrel | Distillation Supplies

Oak wooden spirit keg

Source: book “about spririts” Wateetons.

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