Diplomático RumCraftmanship

Aging Rum Barrels: Where the Best Rum Rests

18 October, 2021

Is a well-rested rum really worth the years of aging it takes to make? This is a decision only the palate can truly determine, but in many ways the aging process is one of the most important components to quality rum-making!

The aging process is integral in the character and flavor profile of every rum. In fact, there exist very few that are bottled without spending some time in barrels first; barrels are essential for the proper execution of aging rum. Come with us as we delve deep into the art of rum casks and the role they play in this age-old mastery.


  • How is Rum Made?

At Diplomático we take great pride in our passionately refined rum making process. From distillation through to finishing, our rums are thoughtfully tended to every step of the way.

The first thing you need to know is that rum is made by fermenting the juice of sugarcane. Following distillation, we fill our vats with new-make spirits, and then it’s time to fill the casks. The type of rum cask or barrel is what determines the unique flavor profile of each individual rum.


Next, it’s aging time! The full casks are sent off to the maturation houses where they will enjoy a lengthy rest up to to 12 years and in some cases more than that. At Diplomático we have 21 aging cellars that house more than 300,000 barrels. The longer the rest, the more premium the final product. When it comes to our Prestige Range, we opt to finish the rums for an additional year or two (after the initial 12) to intensify the taste profile even more. Ex sherry casks are use for Diplomático Selección de Familia, ex Oloroso Sherry casks are used for our Diplomático Single Vintage, while ex Pedro Ximenez sherry casks nurture our Diplomático Ambassador.


During any rum aging process there is a component known (in the industry) as the “angel’s share”. This refers to rum that is lost in each cask due to evaporation. Annually we lose around 7-8% of the liquid in the cask. This means that after a 12 year aging period only 60% of the total volume of the barrel remains. Climatic conditions are what affect the speed and quantity of evaporation — more on this if you read on!


  • Types of Rum Barrels

Let’s take a moment to consider the various types of barrels that rum makers can make use of. Most rum barrels are fashioned out of oak wood. The type of oak will always have an effect on the flavor profile of the liquor, so distilleries will carefully pair their blends to the ideal casks.

Oak, Oak and More Oak

New American oak barrels are a popular choice as they give master blenders autonomy over the flavoring process. It is also common to use casks that once held other liquors, as the oak then offers notes of the previous flavors to the rum.


All Diplomático blends contain rum that was once aged in an ex bourbon cask, and it’s no secret that we also value the depth that an old sherry cask offers to the finishing of a blend (specifically ex Oloroso and ex Pedro Ximénez sherries). In addition to these we also use ex single malt casks and new American oak.


As for cask sizes, professional grade barrels can range anywhere from 1 liter to 200 liters in capacity. Moral of the story: there’s no such thing as too much rum!


  • Climate Matters

Our aging method is a static one, meaning both our barrels and the liquids within them remain totally still in their racks for the duration of the maturation period. Climate also plays a part in the aging of rums, with the most ideal geographical position being anywhere with year round hot days cold nights, and ideally high relative humidity.


If you really want to impress your dinner guests with your rum aging knowledge, inform them that one year of aging in Venezuela is the equivalent of three years in Scotland! This is simply due to the vast differences in climate and the role this plays on the rum.


  • What Does Rum Taste Like

If after reading about the casks you find yourself pondering ‘but what does rum taste like?’, perhaps we can shed some light on this, too! A rum vs. whiskey comparison is often a good place to start, simply due to the similarities that these liquors possess (distilling, aging, blending).


A well-made rum should be smooth, balanced and fragrant. The true flavor of any rum lies in the notes and tones that carry through from the chosen ingredients and barrels that have slowly infused the distilled spirit during maturation.


One of our favorite pastimes here at Diplomático is setting up frequent rum tastings where family, friends and colleagues can come together to share in the taste of the vast rum range. Tasting one rum alongside another helps to amplify both flavor and scent.


  • Single Cask Rum Maturation

Single cask rum maturation refers to a method that is rarely adopted by distilleries. This is the process by which bottled rums come solely from a single cask, as opposed to multiple rums being blended together post-maturation.


The choice of method simply rests on the intention of the distillery when it comes to flavor and finishing. Don’t get left at the bottom of the barrel (pun intended); get to know everything about your favorite rums… and don’t be shy to ask them their age!