Fermentation of the sugarcane juice is by way of natural yeasts found on the cane, while molasses fermentation uses two different third-party sourced distiller's yeast strains, which are used independently to produce two different washes. One of these strains yields a wash with a particularly strong butterscotch flavour, which can be found in many of the distillery's rums. The yeasts are propagated with gradually more molasses introduced in two consecutive mother tanks, then a stainless steel propagation tank before finally being pumped into one of eight open concrete fermenters. Fermentation takes 24 hours, with temperatures up to 34°C to producing a wash of 7% - 8.5% abv.
The wash is then distilled in one of St. Lucia's four different stills: a two column McMillan Ltd Continuous column still made in Prestonpans, Scotland (commissioned in 1985) which produces a distillate at 95% abv; a John Dore (No.1) 422 litre pot still (commissioned in 1998); a Vendome 1,000 litre pot still (commissioned in 2003); and a John Dore (No.2) 6000 litre pot still (commissioned in 2004). Both the John Dore stills have two retort chambers so produce heavy distillates of 80% - 81% abv. (In the tasting room I found the samples from the John Dore No.1 were by far my favourite.)
This array of different stills, each using two different yeast strains, allows the production of various rum styles with many different flavour profiles - thus giving more blending options. The John Dore produces pungent fruity, estery rums while the Vendome, originally mainly used by the bourbon industry, gives the benefit of pot distillation with a rectifying column with variable plates.
St. Lucia Distilleries mostly source white American oak casks from the Kentucky bourbon industry but additionally use Port pipes for final polishing for products such as TØZ. Recently they have also been experimenting with Hermitage and Chilean wine casks, as well as Sherry butts, Madeira and Sauternes barrels. Due to the tropical temperatures, maturation is extremely quick - said to be two-and-a-half times faster than the equivalent in Europe. St Lucia tries to avoid the overly woody notes that can come from extended ageing in such conditions, so they closely monitor the ageing of their rums to judge when mature - rather than being governed by strict age statements. Thus the philosophy at St Lucia is to gain complexity through the blending of older complex rums with fresher, yet characterful rums and so there are no age statements declared on any of their blends. With the exception of caramel for colouring purposes they do not add sugar or other additives to their rums. The water used for hydration prior to bottling is filtered and treated by reverse osmosis.