The Botanical recipe is what makes every gin unique. Since distillation of all ‘Londoní gin demands alcohol of such purity that it is essentially flavourless and odourless, all the taste in gin must be derived from the number, type and amount of botanicals used.
‘Botanicalsí is just another term for the dried herbs, spices and other plant matter that can add flavour and/or aroma to gin. By law, gin must contain Juniper berries, and these must be the dominant component in the recipe - otherwise, itís not gin. After that, pretty well anything goes, and this is where the skill and imagination of the gin maker come into play.
SW4 London Dry Gin uses 12 botanicals. The exact quantities are a closely guarded secret, but these are the ingredients we use.
SW4 London Dry Gin is the result of two separate distillation processes.
First the production of a high strength (minimum 96% ABV) neutral spirit is necessary. This spirit must be exceptionally pure, with residues not exceeding strict regulatory guidelines. According to the Gin and Vodka Association, ”the finest raw materials for this ’neutral’ spirit are either grain (normally barley or maize) or molasses. The best neutral alcohol has no flavour at all.” SW4 London Dry Gin uses grain as its base. The neutral spirit is normally produced on a modern continuous column or refluxing still, a highly efficient means of producing very pure high strength alcohol.
Once we have a suitable neutral grain spirit, we can move on to the second distillation. For SW4 London Dry Gin, this is always a batch distillation, done in a traditional pot still. Neutral grain spirit is added into the pot still, togther with the botanicals. In most cases the spirit is also diluted by adding pure water to reach a strength of about 45% ABV (so, a mix of half spirit, half water, plus the botanicals).
The botanicals contain essential oils immediately below the skin of the seed, berry, peel or bark and it is the extraction of these, in the presence of alcohol, that gives SW4 London Dry Gin its unique flavour. The mixture is left to steep, or macerate, overnight, typically for between 12-24 hours. In this time, the botanicals release their flavours, which are absorbed into the spirit and water solution.
Next comes the actual distillation of the gin. Because ethanol and water have different boiling points, we can separate one from the other. Once the maceration is complete, the pot still is heated slowly. The ethanol boils at 78.5C, well before the water. As it boils, the ethanol turns to vapour which rises up the neck of the still. It carries with it the different flavours from the botanicals which are inside the still. The lower quality early part of the distillation (‘foreshotsí) and end of the run (‘feintsí), are run off to be redistilled. Only the ’heart’ of the run is used to produce high quality gin; this is run off at about 80-85% ABV. For a ‘Londoní gin like SW4, only further neutral alcohol, water and minute amounts of sugar can be added after distillation. Finally, the pure gin is the left to ‘restí for a period of time, so that the flavours and the alcohol can marry properly. Then the spirit is diluted to 40% ABV before being bottled.