History & method
The solera method or systema solera originates from Spain and more specifically the Xérès (Jerez) region and is used for the aging of its well-known fortified wine: Sherry.
This is an aging system that blends between ages to say it extremely simplified. In the Solera method barrels are stacked on top of each other in rows, called criaderas. The barrels with the oldest sherry are on the bottom and are called the solera level (solera loosely meaning floor or ground). The barrels with the second-oldest sherry are on top of these and on top of those barrels are yet another row of slightly younger sherry, there can be up to 14-20 layers of criaderas or layers depending on the type of sherry. For the example provided by a beautiful tattoo of a good friend of mine (who adores sherry) I’ll be using 3 rows, so the solera level and 2 criaderas

Every time sherry is taken from the bottom row for bottling, these barrels are filled up with sherry from the row above, and so on. The barrels are never fully emptied therefore you get a perpetual and constant flavor profile and quality. The younger sherry will blend with the older sherry and so the whole of these 2 will be a slightly younger sherry.
The amount of liquid taken from the barrels can vary, so the ratio of young to old sherry can be different every time
This also means that theoretically there can be some part of the liquid from the beginning of the aging process left in the current blend.
On the Solera level you then have a sherry that has an age range or a calculated average age. This is possible through very closely monitoring how much sherry is moved from what row at what age, all of this is very complicated so I won’t to this kind of math myself (later I’ll try my hand at a simpler equation though).
The sherry in the solera level will then be bottled and is ready for drinking.
Specific age statement in sherry are quite rare as opposed to whisky, rum or other aged spirits. And here starts the controversy with rum that’s been aged using the Solera method.
The problem
The next part is mostly personal opinion supported by facts.
The problem in the rum world has to do with the addition of age statements. I -like many others- will focus on the punching bag of rum geeks: Zacapa 23. I’m not going to discuss the quality, adulteration or in this rum or those like it, since this is not the article to do so. What I will discuss is the 23 on that label and their aging system.

So… whenever you look at a bottle of Zacapa, a 23 will be prominently displayed on the label. Officially Zacapa says this is not a specific age statement, since this is the age of the oldest rum in the ‘solera’ (which in Zacapa’s case isn’t even a real solera) blend of 6 to 23 year old. This is like saying a 30 year old smoker is 60 since his lungs are those of a 60 year old, but he’s not… he’s 30… okay. Not the best comparison, I know, but it’s just to make my point clear.
In the world of spirits, it’s expected that when a number is placed center stage on a label it’s the minimum age. This is thanks to the strict regulations surrounding whisky. With solera aging, following this rule would do no justice to the rum since it’s a completely different version of aging than static aging and blending. In my opinion there remain 2 honest options then, you mention an average age/ an age range, and clearly mentioned it (not on the back label). Or you don’t mention any age at all, just like Santa Teresa does with it’s 1796 (you must be really dense to believe 1796 has anything to do with the rum’s age).
Back to Zacapa. Next to their highly confusing bordering-to-lying age statement they also don’t really use the Solera method. Even though it does says so on the bottle.
As you can see in this chart, from Zacapa themselves this isn’t even remotely the same as the traditional solera method. And it’s just extremely confusing.
I don’t know if it’s just my tiny 22 year old brain, but damn… there are a lot of arrows and barrels to keep track of. I honestly believe this is a system Zacapa has worked on long and hard to develop to get a consistent rum. BUT IT ISN’T SOLERA! So don’t label it as such.
Conclusion
Okay, I kind of got on a rant there. But to conclude:
Systema solera is a beautiful, easy and effective way of aging your liquid with an admirable consistency. In sherry, this creates amazing tipples and it can do the same in other spirits, such as rum. What we do have to take into consideration is the age statements that are put on bottles. If they show something that can obviously be mistaken as an age, we’ve got a problem of misleading the consumer towards misinformation and they’ll buy a product that’s actually worth less than what they’re lead to believe.
If however you use this method and honestly market your product to the consumer, I salute you. Because solera rums can and are lovely drinks indeed. Rums such as the aforementioned Santa Teresa 1796 are great rums in their own right and I truly enjoy drinking them now and then. Here the saying “drink what you like, but know what you’re drinking” pops into mind. If producers are honest about their product, and the quality of their rums are still what consumers want, sales won’t drop. The only thing producers do is increase transparency. This will be highly appreciated by casual drinkers and rum geeks alike.
-Robin Pollet, just a guy who likes rum
If you think/know I’m completely wrong (factual, or in my opinions), or have anything to add. Please feel free to contact me with constructive feedback at the.rum.robin@gmail.com
I love to be proven wrong 😊
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