Most rum is made in the tropics, where sugar cane grows. But when it comes time to age the spirit, some distillers are drawing inspiration from the solera system, a technique that originated in Spain with brandy and sherry makers.

A traditional solera system blends younger and older liquids together as they mature. They’re aged in barrels, and may be arranged in rows and stacked vertically. The bottom row, or solera (which means “on the ground”), contains the oldest liquids. The middle row of barrels, called the first criaderas (nurseries), holds the intermediate-aged, and the youngest are stored in the top row or second criaderas.

Using the principles of solera, rum is drawn from the bottom level when it’s ready for bottling. Then an equal portion of younger rum is dispensed from the level above, and the uppermost barrel is replenished with new rum to continue the aging process.

Fans say solera brings out the best of the rums; the younger rums take on the characteristics of the older ones, creating a balance of flavours that exceeds the sum of its parts. Because it’s up to the master blender to decide when to draw the rums from the barrels to achieve the desired complexity and consistency, this can also result in some truly distinctive blends. “It’s about creating something new and different,” says Miguel Riascos, a third-generation rum maker at the La Hechicera distillery in Colombia. “Everyone does it differently. That’s the beauty of this industry.”