The Glenlivet Rum and Bourbon Fusion Cask Selection changes all that. In a first for Scotch, the new bottling has been finished in bespoke casks crafted from a combination of first-fill rum and ...

and is much more porous than American or European oak, making it prone to leakage. Cask makers have to be extra careful not to waste a harvest, as another tree won't be ready for centuries.