Solera Aging Process Explained

While the solera aging process itself has been around for a couple centuries now, it seems like some of the more prominent whiskey production companies are starting to rely on this process to age their spirits. Why is this trend happening? What exactly is it, anyway? And does any of this really impact the final product? We’re here to break it all down.


Market Forces

Whiskey might seem like a simple product. Distill a bunch of spirits, chuck it in a barrel, and take it out when it’s done. But the business of whiskey production is much more complicated. Because there’s a significant lag between when the whiskey is distilled and when it can be bottled — sometimes decades or more — the distillery needs to be able to very accurately forecast how much product they are going to need in the future.

That isn’t always easy. The whiskey bubble of the 1960’s and 1970’s was a hard earned lesson for many distilleries, and a perfect illustration of market forces in action. In the Mad-Men-1950’s, whiskey was in short supply with distilleries unable to make enough to meet the rampant demand. As a result, those distilleries started churning out new whiskey, stocking it in their cellars expecting to turn a huge profit in a few years. The problem was that by the time the whiskey was ready, the market had shunned whiskey in favor of vodka and demand plummeted. Distilleries were left with huge quantities of whiskey for which they had no buyer, a massive liability and expense, and many of them would never financially recover.

Here in 2020, the whiskey manufacturers find themselves in a similar situation to the 1950’s. There’s a massive demand for whiskey in the market and, while whiskey in general is doing well, there are specific brands that are doing better than others. The whiskey drinking public seems much better educated about their spirits these days and, as a result, the more highly-esteemed distilleries are selling out almost as soon as the spirit hits the shelves.

As a way to keep producing high quality spirits in a more consistent and repeatable process, some distillers are turning to the solera aging method to help ride out the spikes and valleys in demand for their product.

The Normal Whiskey Aging Process

Whiskey, made the traditional way, is a time capsule in a bottle. It’s a product that was grown, distilled, and barreled at a specific point in time (typically, many years in the past). Some distillers never even get to enjoy the fruits of their labor once they put the whiskey in the barrel, sending it into the future for future generations to enjoy instead. You can almost feel the fingerprint of the people who made it when you open these bottles.

Especially with bourbon, barrels are brand new for each run of whiskey and used only once. The whiskey goes into the barrel, the head distiller tastes it along the way, and once the whiskey is ready the barrel is dumped out and the contents bottled. Sometimes multiple barrels are combined to make a single run of whiskey — but either way, once the barrel is empty, that’s the end of its life.

The Van Winkle family owned and ran the Stitzel-Weller distillery during its heyday, and the whiskey that they produced is highly sought after by knowledgeable whiskey connoisseurs. Sadly, the facility was purchased in 1972 by a company that would later become the British spirits giant Diageo and the plant was almost immediately shut down. Some of the prized whiskey that was still aging in their warehouse would go on to become part of the Crown Royal mix for a while, and other barrels were purchased by the Van Winkle family for their own bottling purposes… but over time, the stocks were depleted.

Recently, Diageo realized that they had let a goldmine slip through their fingers. They only had a few barrels of whiskey left at this point — not enough to sustain an operation. Using the traditional methods, that whiskey would be used and gone in a heartbeat. They needed a different option, and they turned to the solera method for help.

The Solera Method

With a whiskey aged in the normal way, it’s an all or nothing kind of deal. Once the barrel is tapped, the entire contents of the barrel are disgorged and bottled. And that is precisely what the solera method aims to change.

With the solera aging method, instead of emptying the entire barrel, only a portion (typically around half) of the contents are removed. The rest of that original product remains behind, and then newly produced product is added to restore the barrel to full capacity. The mixture is then placed back into storage to age.

This process was pioneered in Spain; according to that traditional method, a series of casks would be used to gently age the liquid inside. With each cycle, some of the volume of the oldest casks would be drained off and sold, with the now missing volume being replaced from the next oldest cask in line. This pattern would be repeated, with the younger casks donating some of their contents to the slightly diminished older casks, until the youngest cask was reached. There, the newly made liquid would be added to start its way through the process.

Please enjoy my powerpoint skills. I am not a graphic designer.

Some producers who use this method arrange their casks vertically, such that gravity can assist the flow of liquid from the “young” casks on top finally ending in the oldest casks in the bottom. The word “solera” means “on the ground” in Spanish, referring to the oldest casks on the bottom of the stack.

The idea here is to try and produce a product that is more consistent — more reliable in flavor — than if new barrels were used every time. In theory, each successive bottle should taste almost exactly like the previous one.

If done properly this can create a more elastic and consistent pipeline for spirits. When times are a bit slack, the whiskey can just stay in the barrels and continue to age. But when the demand ramps up, the pipeline can start to flow once more, with the exact same flavor profile coming out as before.

The problem arises when companies like Blade & Bow start using this process to add a splash of history to new whiskey, especially when it doesn’t come from the same source.

First, this is the whiskey equivalent of the Ship of Theseus. For those who prize the Stitzel-Weller distilled whiskey, part of the appeal is that story and that history. In the early stages, there’s undoubtedly some of that original whiskey that comes in each bottle, but with each successive repetition of the process there’s a lower and lower percentage of that original spirit in each bottle. At what point does the whiskey in the bottle no longer resemble the original spirit? When can it no longer be called Stitzel-Weller whiskey? According to the solera method, this can continue indefinitely, even after the last original molecule of original whiskey has been removed.

The second issue is that the whiskey that is added to the barrel needs to be identical in source to the whiskey that was removed. It needs to be the same grain bill, the same age (well, one year younger), and had the same care and attention given to it. The sherry manufacturers who use this process, for example, take great care to have a series of barrels evenly spaced in terms of how long the liquid has been in each, and regularly rotate that spirit. Three barrels placed one year apart, where half the liquid is shifted every year, produces a continuous and consistent flow of sherry of equivalent quality that’s about three years old. In a situation where there’s over 40 years of time between the old and new whiskey, where the spirit being added isn’t even from the same plant or the same distilling family, its difficult to imagine that the flavor profile wouldn’t drift away from where it started.


Solera Process: Good Or Bad?

Admittedly, that section heading my be a little more reductive than I’d like to get. It’s not quite that black and white. The solera method is just another aging process, like many others used by manufacturers to age and flavor their spirits. Some aging processes have better results than others, and much of it depends on application of the process and what you are looking to accomplish.

A distillery doing a proper solera aging method for their whiskey can undoubtedly produce some fantastic and consistent product. And once they get into the groove, they can just keep cranking it out for centuries to come without much drift in quality.

My only issue with the process is when it is used deceptively. Blade & Bow is brand that relies heavily on their Stitzel-Weller heritage, and they are only using the solera process to extend the lifetime of the original stock dating back to the 1980’s. They talk about adding “other, younger whiskey” — but never really make it clear that the younger whiskey is a different stock from a different distillery. That part is conveniently left out of the marketing.

Done for the right reasons and in the correct way, the solera method can be a fantastic tool. Done for the wrong reasons, it can be used to deceptively hide a lot of unpleasant truths from the end consumer.



  1. For the life of me you can not call a solera process a bourbon. If you are replacing the contents of a barrel you are not using a new barrell.

    1. I agree with C.
      The solera method does not meet the criteria for bourbon. I have a bottle of Hillrock and on the front label it says it is solera aged bourbon whiskey. It is a beautiful bottle and the whiskey is very yummy, but solera aged bourbon simply cannot exist.

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