Cask & Climate

A rum aged in a barrel on Barbados matures faster than a whisky in Scotland. The heat drives the alcohol deep into the wood, releasing vanilla, roasted notes, and tannins, with oxygen playing its part too. But that same heat also causes rum to evaporate. Trade publications often cite around eight percent a year for the Caribbean, compared with roughly two percent in Scotland.

Used bourbon barrels made of American oak serve as the primary casks. For Mount Gay Eclipse Black, importers cite barrels from Kentucky, in which the rums rested for two to seven years. St Nicholas Abbey also ages in used bourbon barrels, according to the estate. Used barrels impart less wood flavor than new ones, keeping the rum fruitier and rounder.

Water comes into play at bottling. After aging, rum is diluted to drinking strength, and Mount Gay cites the island's own filtered coral-limestone water for this purpose. Whether this water is noticeably present in the taste is a matter of opinion, but it's part of the story the houses tell.

Anyone reading an age statement on a label should know the rules. Under EU law, an age statement may only name the youngest component in a blend. A rum labeled '12' therefore consists entirely of rums aged at least twelve years. Nor can the aging year be simply converted: counting one tropical year as equivalent to three European years is marketing, not a chemically proven one-to-one equation.