When I was interviewed for a job heading up a new malt whiskey-focused farm distillery in rural Quebec, I was asked by the owners what I thought was the most important production factor for making the best whiskey possible. Without hesitation, I began talking about the need for a diverse and innovative cask program. Within my answer I even went so far as to put forth a template plan for cask types, future blend percentages, and line extensions. I found out later that answer was what got me the job.

The owners were not distillers themselves, but they were attentive and avid fans of the profession, paying close attention to the production and flavors coming from their favorite drams. Eventually they began to see what many of us in the industry see every day: The cask is integral to quality spirit production.

I’ve lost track of the number of times I’ve heard the phrase, “barrels make up 70–90% of a whiskey’s flavor.” Setting aside that I’m not entirely sure what metrics are being used to quantify “flavor,” I think that for many spirit types, these words largely ring true. There is something alchemical and almost magical about cask maturation. The white spirit enters the barrel as a brash and rude liquid neophyte and emerges (hopefully) smoothed, matured, and coifed for the real world.

It’s hard not be taken in by the wonder and aroma of a properly maintained maturation warehouse. Whether it be the cool dunnage systems throughout Scotland or the hot and dry rick houses dotting the Kentucky landscape, you can’t help but fall in love with their spartan design and primitive allure. These are altars to the idea that time and patience are the perfect finishing ingredients for spirits that cannot easily be improved upon.

Casks are the sporks of the distilling industry. That is to say, a game changer. This can’t be overstated. Prior to the use of casks for the maturation of spirit, they were merely viewed as containers; a transient vessel to hold spiritous liquid for the purposes of transportation or easy serving. Wooden casks became the CD’s to the clay amphora’s cassette tapes of the day. They were more efficient, robust, and easier to move. However, until the advent of toasted and charred barrels, they were considered little more than holding tanks.

Eventually, fire entered the mix and the cask evolved into something more than a vessel. It became part of the recipe, an ingredient — and it has forever altered the spirits we consume today. Through various physical and chemical reactions between cask and spirit, we see rough-hewn white liquors transformed into bolder and haute impressions of their former selves. Would Jack Daniels or Jim Beam taste the same were it not for the use of newly charred American oak? The Macallan sherry bomb would not exist were it not for careful cask selection and management. The famous Cognacs of southern France would likely remain fiery and rustic without the addition of state-run old growth oak forests.

So, to make many of the world class spirits we know and love, a cask must enter the picture at some point. Several of these spirits require either through tradition or law a specific type or class of cask. Most American whiskeys must legally be aged in new charred oak barrels. Caribbean rums are typically aged in used bourbon casks, while Cognac and its older brother Armagnac are almost exclusively aged in toasted French oak. If you know what you’re producing, then choosing a barrel is seemingly the easiest decision to make.

Sometimes it really is that simple. Buy barrel. Put liquid in barrel. Wait and then bottle. However, like most things in life, there’s a difference between simply doing something and doing it well. This is where the principles of cask management come into play.

In my view, cask management begins with the selection of the standing tree to be converted into stave wood and ends with the final blend. All along the middle there are roads, routes, and rivulets that we can meander down to further alter the character and effects of the maturation process. In the end, I believe most distillers want to make a high-quality product. This becomes much easier and more consistent when we fully grasp the potential of the tools of our trade, casks included.

And that, my friends, is the raison d’être for this book. Like much else in the distilling industry, finding reliable information and learning materials to better your craft can often feel like a daunting task. In the kingdom of alcoholic beverages, distilled spirits come off as arcane witchcraft and sorcery. Far more research and time has been spent learning and explaining the scientific minutiae of wine and beer. Spirits have typically received the short end of the information shaft.

Distillers are usually a convivial folk, and most don’t mind sharing information, but that’s still far from ideal with regards to raising the technical level of the industry as a whole. We need to move beyond the anecdotal and apocryphal into the realm of fastidious research. Sure, the internet is your friend, but it’s not your only friend.

The story of cask management is just like any other story. First it requires a beginning. For us, that beginning is in the forests where our cask wood grows. To understand how to better manage our barrels and maximize their potential for our products, we need to understand where this particular ingredient comes from. There is understandably a sort of terroir with regards to oak and differences in location and growth factors can have pronounced effects on the sensory character of the finished barrel. This ignores the obvious differences that can arise from the different species of oak or even different types of wood apart from oak. We will explore what makes American oak different from French oak, Oregon oak, and Japanese oak. And for the sake of cat-killing curiosity, we will look at a few woods making minor headway into the spirits industry such as chestnut and acacia.

Tree felling and stave cutting are not insignificant tasks. Neither is the crucial time of stave drying, whether it is in a field of stave ricks or through forced air drying. We will discuss the benefits and disadvantages of both and how they affect the final barrel.

Moving into the cooper’s workshop, we discuss the basic techniques for shaping the cask from stave selection to heading. This is also when fire is introduced to the stave wood and we toast or char the barrel to the desired specifications. How this is done has a profound impact on the wood chemistry and subsequent sensory characters that our casks contribute.

In Chapter 2, we get down to the molecular level of the cask to explore some of the important chemical changes that casks can contribute to immature spirits. These reactions are roughly grouped into four major classes: reductive, additive, subtractive, and productive. We will explore them all and how they can be manipulated in subtle ways to give us more control over the maturation process.

Chapter 3 is where we begin the process of selecting our cask. Barrels should be selected for the express purpose of modifying our spirit in ways that we find desirable. Certainly, what may be desirable for one person may be anathema to the next. This chapter deals with that disparity by tackling the many factors that go into cask selection and how they may alter the spirit maturation process. This includes barrel sizing considerations, char and toast levels, and the use of used barrels.

Chapter 4 is interesting in that here we step away from the cask to look at the warehouse itself. The warehouse is effectively the cask that contains the cask, and its materials of construction and environment are every bit as important as the casks themselves. This section deals with the common warehouse designs, their construction, and the advantages and disadvantages of each as well as safety and work-flow considerations. Next, we talk about the warehouse micro-climate and macro-climate and how these affect the maturation of the casks contained therein. Finally, this chapter goes into more detail about the common aging and physical placement systems currently in use and how they affect the maturation process.

Chapter 5, for some people, may seem like the crux of this book, and in some ways it is, though this comes with the caveat that nothing in chapter 5 will mean much if we don’t pay heed to chapters 1–4. This chapter is all about maturation techniques. This section is front-loaded with traditional aging techniques for the world’s best-known spirits including American whiskey, Scotch whiskey, French brandy, rum, and tequila. Of course, I am a big proponent of studying as many distilling traditions as possible, so this chapter contains information on what some might call “alternative” maturation techniques, which includes such concepts as stave additions, alcohol adjustments, and oak extract additions.

Chapter 6 deals with blending and the minutiae of the blender’s art. As an art, blending is not something that can necessarily be taught but must be experienced first-hand for the practitioner to hone their skills. All the same, there are quite a few standards and techniques practiced throughout the industry that we will treat as suggested practices for the would-be blender.

Chapter 7 takes a shallow dive into the world of sensory analysis. Every distillery should consider implementing a formalized sensory program to ensure consistency and better understand their products. This chapter includes building and training a sensory panel for simple discriminatory tests as well as basic statistical approaches for their assessment.

Chapter 8 is all about physical cask maintenance. Wood is a porous and organic material, meaning it is structurally prone to problems if not well attended to. Barrels can leak. They can dry out during storage. Mold can grow on them. These and many other issues can occur if the distiller is not paying attention or properly maintaining their casks. This chapter speaks to the handyman living in all of us and attempts to set out a simple set of techniques that can be used to assess barrels upon receipt from the cooper or broker, proper storage conditions, repair techniques, and basic coopering concepts. Barrels may serve as ingredients, but they are also tools and we must be diligent about keeping our tools in top condition.

When I teach classes and workshops, I have always had a simple view on sharing information with students. I believe that with rare exception there is no one correct way to do something in the spirits industry. That is probably why I find this industry so freeing when compared to brewing or winemaking. The motto that a friend and I coined at a conference one year discussing this very thing is, “Tools, not rules.” I believe the contents of my courses and, by extension, this very book should be treated not as dictums for how something must be done but rather how it can be done. If you line up 100 bourbon distillers and ask them how to make bourbon, you will likely wind up with close to 100 different answers, and most of those answers would produce some delicious liquor. I cannot tell you how to run your cask program. I can only show you techniques and hopefully give you some ideas and inspiration on how to improve your processes.

So, we begin our journey down the rabbit hole of spirit cask management. Cheers to your journey. I hope to someday share a dram with you on the other side. 

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Matt Strickland
Matt Strickland currently heads up operations at Distillerie Côte des Saints, a farm distillery and malting house in Mirabel, QC, Canada. Matt has a masters in science from Oregon State University where he studied Oenology and Viticulture. He is a faculty member at Moonshine University (where he teaches their whiskey production course) and Siebel Institute (distillation theory and environmental practices). Matt is also the only American distiller to sit on the Board of Examiners for the Institute of Brewing and Distilling in the UK. He has a wife and two daughters. Subsequently, he has been told that purple is his favorite color and unicorns are apparently awesome.