Cask & Climate

When a cask sits in a Scottish warehouse, the weather shifts with the seasons. In Guyana, it barely changes at all. The specification for Demerara Rum describes warehouses at sea level with temperatures between roughly 24 and 32 degrees Celsius and humidity around 70 percent. Several such warehouses stand on the Diamond estate, close to the banks of the Demerara River.

Maturation usually takes place in white oak casks. According to the trade, the rums of El Dorado 12 and 15 rest in used bourbon casks. Such casks have already held whiskey and therefore release fewer raw wood notes, offering instead vanilla, caramel and spice. The wood works faster in the heat, as alcohol and water penetrate deeper into it and draw back out again.

The price of this is evaporation. Trade publications cite losses in tropical warehouses often around eight percent a year, compared with about two percent in Scotland. These aren't measured figures from a single study but rough benchmarks that vary widely depending on the warehouse, cask size and location. After 15 years of such losses, only a fraction of what was originally filled remains.

This also explains the price of old tropical rums and the age statement on the label. In the EU, an age statement may only be given if it refers to the youngest rum in the blend, and the maturation must have taken place under the tax supervision of a member state or an equivalent control. A "12" or "15" on an El Dorado bottle therefore means, within the EU: everything in it is at least that old.

The specification for Demerara Rum also protects certain terms. "Cask Aged," "Special Reserve" and "Grand Special Reserve" must be bottled in Demerara, and sweetening is capped at 20 grams per liter. A well-known saying claims that one year in the tropics equals three years in Europe. This is a popular marketing rule of thumb, though it can't be proven chemically on a one-to-one basis.