The story behind Glenfiddich Solera on its 25th anniversary

This year marks the 25th anniversary since Glenfiddich 15 Year Old Single Malt Scotch Whisky was changed forever by the introduction of a solera system at the distillery. The story behind this whisky is an interesting one, so we spoke with malt master and chief whisky maker Brian Kinsman to learn how a Scotch whisky distillery ended up using a process inspired by sherry.

Prior to Glenfiddich Solera, the Speyside distillery created an expression called Glenfiddich 15-year-old Cask Strength. It was bottled at a higher strength of 51% ABV and was a marriage of American and European oak. This is no longer bottled, as it replaced by the whisky we’re interested in today. 

The inspiration for which came from a trip that former Glenfiddich malt master and Balvenie legend David. C Stewart MBE undertook with a member of the Grant Gordon family to some sherry houses in Spain, back in the late 1990s. There they observed the solera system. 

What is a Solera system?

Used primarily for aging sherry, the solera system is a process that involves the blending of various vintages of sherry over time. It’s labour-intensive and requires significant skill and knowledge to make it work. But it’s utlised all over Jerez for a reason. The solera system is not only crucial in producing the unique characteristics of sherry, but is prized for its ability to ensure consistency in flavour. 

The Solera system is used for all different types of sherry, like fino, amontillado, oloroso, and others. The type of sherry, the length of ageing, and the specific practices can vary, which means in every bodega every sherry solera is unique and will represent a range of flavours and styles.

How the solera system works

The system has various stages to it. It begins with layered barrel stacking, where barrels are assembled in a pyramid-like structure. The bottom layer is called the solera and it contains the oldest sherry. Above it are successive layers of younger sherries, known as criaderas, the number of which can vary.

When the sherry is extracted for bottling, it’s taken from the solera layer (this process is called the saca), typically around a third of the barrel’s content. Once the sherry is extracted from the solera barrels, they are refilled with sherry from the criadera layer directly above the solera. This criadera is then refilled with sherry from the one above it, and so on. New sherry from the latest harvest, named sobretabla, is filled into the top criadera and the system goes on. 

It’s a continuous ageing process that ensures a consistent mix of ages and vintages in each barrel. The older sherries have complexity and depth, but the younger sherries play a big role here too, contributing freshness and fruitiness. 

A solera in Scotch

It’s a complex system so you would think it might be difficult to translate the process and recreate in Scotch whisky, but Kinsman says it was relatively straightforward to create a solera in a Scotch whisky distillery. “We have maintained a very traditional approach to single malt over the years including using 2,000-litre oak marrying tuns and wooden washbacks in the distillery. That meant we were able to tap into local expertise to have a bespoke wooden vat built to hold the whisky”.  

At Glenfiddich, there is a main solera vat, one that was installed in 1998. It was filled with 15-year-old Glenfiddich and has remained at least half full to this day. It holds approximately 35,000 litres of 15-year-old Glenfiddich and at the time of writing it is full to the top with a batch of Solera. The whisky in there is at a cask strength of 58% and it will be drawn down to half when the whisky is sent for bottling. Then another batch will be filled into the vat. The process never stops!

Each component is vatted separately and then brought together in the solera vat, with three components in the recipe of Solera. Kinsman defines them as the following:

Glenfiddich 15-year-old matured in American oak bourbon and refill. This brings the core character of the whisky.

Glenfiddich 15-year-old matured in European oak sherry casks. This brings richness, depth, and complexity to the final product.

Glenfiddich 15-year-old finished in virgin American oak for up to 6 months. This adds spice, sweetness, and a rich oakiness.

The purpose of the solera

You can see how the Scotch solera that Glenfiddich uses mirrors the Spanish solera system, as the different whiskies are all bringing in a new element. It also ensures consistency and depth of flavour across each bottling. As Kinsman explains, “By constantly adding to the previous batch we have a lineage of solera single malt that goes all the way back to the very first vatting in 1998. The whisky remains 15 years old as it does not gain any age in the vat. Each batch contains 50% from the previous batch giving a highly consistent whisky for bottling”.  

I’d love to see a solera used with a huge variety of ages and vintages by a whisky distillery someday. But at Glenfiddich, the whisky must be kept at the minimum age of 15 years old so it can be bottled with the age statement. This is very much an interpretation of the solera system rather than a straight imitation. “So our take on the process is to mix together a fixed recipe of oak types and to keep the vat continually half full to create a link between every single bottle ever bottled,” Kinsman summarises. 

I don’t know about anyone else, but a big vat full of constantly evolving whisky is something I want in my house. Now. But then I’m not sure I could trust myself to not constantly be ladelling out a portion to taste. Kinsman tells me that if I did that at Glenfiddich I would be richly rewarded by a world of flavour. “It is sublime! One of the best experiences in the distillery is to lean into the top of the vat and catch the aroma in the air. It is literally breathtaking!  Having a small sip of cask strength solera while standing in warehouse 8 beside the Solera Vat is an experience of a lifetime for some of our visitors”.    

Traditions and trials

The creation of the solera system and the redefining of Glenfiddich 15 Year Old Single Malt Scotch Whisky is part of a wider attempt to push the envelope for Kinsman, whose role balances experimentation while overseeing the continuance of arguably the most definitive single malt in the world, Glenfiddich 12 Year Old, and the distillery’s other core expressions.

“It is a constant balancing act of maintaining the traditions at the distillery while looking for opportunities to create new and interesting expressions. It is essential that I maintain the quality of globally famous products like Glenfiddich 12 Years Old, 15 Year Old Solera, and 18 Year Old. These have become firm favourites around the world and keeping the same flavour profile is one of our key objectives”.

Alongside this, he says that Glenfiddich is always looking for opportunities to explore new casks for maturation and ways to create interesting flavours. It’s an approach that has led to the Glenfiddich Experimental Series and Grand Range. Long may Kinsman pioneer, I say, as a fan of Glenfiddich 15 Year Old Single Malt Scotch Whisky. We have a tasting below. Now, if you’ll excuse me, I’m working out how to build a solera vat in a two-up-two-down house in a town centre. I knew that cellar would come in handy…

Glenfiddich 15 Year Old Single Malt Scotch Whisky tasting note:

Nose: Sherry, citrus – orange in particular – drying oak spice, heather honey, and dark fruit.

Palate: Marzipan, raisins, fruitcake, cinnamon, and fudge.

Finish: Candied fruits, raisins, spices, Christmas pudding, oak takes over.

*an outstanding resource for those who want to learn more.

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