Four years of aging on Scotland’s west coast can actually result in a gain of five liters of water. In chilly wine caves and the low, single-story warehouses of cold, damp Scotland, barrels lose more ethanol; in the hotter American South, they tend to lose water—a factor exacerbated by the metal-sided rickhouses. They get much hotter on the high floors, which is why “small batch” or “single barrel” bourbon can be so interesting—those casks are selected for being accidentally better than the barrels around them.
