Sugarcane can be hand- or machine-harvested. The cane is then cut into 20 cm lengths and sent to be crushed as soon as possible in order to minimize the deterioration of the sugar contained in the cane.
After crushing, the juice is run off and prepared for fermentation in order to transform the sugar into alcohol. The resulting "sugar wine" is either immediately vatted, for agricultural rums, or heated several times to make sugar and molasses for rum. The sugar is transformed into alcohol through the action of yeast.
Fermentation may last just a few hours (for light rums), for several days (for more complex rums), or even for several weeks (for the finest rums).
Distillation can begin once the sugar wine has been produced (7% alcohol). All rums were originally distilled in small pot stills, but nowadays most rums are distilled continuously in single or multiple column stills. The benefit of this modern technique, first introduced in Cuba in the 19th century, is that it produces a lighter spirit in greater quantities and in a shorter time. The pot still technique, which takes longer and is harder to master, is still used in Jamaica, Barbados, Santa Lucia, Haiti and Guyana.
Once the wine has been distilled, the new spirit is either bottled directly (white rum) or aged in wooden casks (dark and amber rums). Most of the barrels used in the Caribbean are young bourbon casks of American oak that give the rum vanilla, spice and slightly smoky notes. It is also said that one year of aging in the hot and humid climate of the Caribbean is equivalent to three or four years in the Maison Ferrand, which explains why it is very difficult to keep rum for more than eight to ten years.