Who’s Afraid of Heads, Hearts, and Tails?


Heads, hearts, and tails. Three simple words. But they inspire awe and fear in the hearts of many beginning distillers. Should we be afraid of heads, hearts, and tails? This iStill Blog post aims to answer that question in a few simple steps.

First, let’s investigate what heads, hearts, and tails are. Then, we’ll research their properties. As a third step, let us assess why heads, hearts, and tails are important – and often awe-inspiring. The final part of this blog post will propose a framework for you to manage heads, hearts, and tails cuts.

Heads, Hearts, and Tails: what are they?

Not al alcohol is ethanol and not all alcohol is created equal. Where ethanol is intoxicating without being toxic, when consumed in moderate amounts, some other alcohols are actually quite toxic, even when consumed in very limited amounts.

During distillation – especially in the lower power-input and higher-proof finishing runs – the good alcohol we call ethanol comes over in the middle, during the “heart” of the run. The other alcohols, with high toxicity, come over at the beginning and end of the finishing run. The first part of the run is therefor called “heads”, while the last part is named “tails”.

So basically heads and tails are phases during the distillation run, when overly toxic alcohols come over. Does it start to make sense why they are fear-inducing? Cut too many heads and tails into your hearts and you end up with a toxic spirit.

Okay, the bad news is that heads and tails are really bad. The good news is that they only come over in the beginning and at the end of the run, and the actual amounts are small. But what are their properties? Let’s dive in deeper.

Heads, Hearts, and Tails: what are their properties?

Scientifically, a better name for “heads” is “lower boiling point alcohols”. The alcohols with low boiling points come over early in the run. Think aceton or methanol. A better name for “tails” is “high boiling point alcohols”. Propanol, butanol, and furfural come over late in the run, because they boil off at very high temperatures. Higher than ethanol, and sometimes higher than water.

In general, low boiling point alcohols cause head-aches. High boiling point alcohols create stomach problems. Mnemonic? Heads give head-aches, where tails create tail-end issues.

Floral and fruity flavors come over during the first part of the distillation run. Floral and fruity flavors associate with heads. Rooty, nutty, and earthy flavors come over during the last part of the run and associate with tails. Do you feel a catch 22 coming? Here it is. If you want to cut out all heads, you’ll cut out all floral and fruity flavors as well. Do you want to get rid of tails? Great, stills (or run procedures) can do that for you. But you’ll loose all rooty, nutty, and earthy flavors as well.

Why are heads, hearts, and tails important – and awe-inspiring?

Cut in too many heads and you end up with a spirit that causes head-aches. Cut out too many heads and you end up with a spirit that lost its floral and fruity flavors. Idem for tails. Do you start to see why cutting for heads, hearts, and tails is important – and awe-inspiring at the same time? Good cuts make great product. Poor cuts destroy your product. In a way a good distiller is someone that knows how to make great cuts. In a way a great still is a machine that controls the cut-points for heads, hearts, and tails to perfection. In a way distilling comes down to cutting.

So far, the industry has seen two approaches on how to deal with this issue. Big Alcohol has often been accused to just cut everything in. It explains the morning-afters. It makes for a good amount of profit, since the manufacturer doesn’t have to cut out anything and all alcohols produced end up in a bottle. A bottle being sold to you.

The second school of thought, that started with the birth of craft distillation, aimed to cut out heads and tails all-together. The result? You can guess it, right? Uninteresting spirits.

Our insight, based on science, brought a third way of looking at heads, hearts, and tails to the forefront: the one we shared above, where heads, hearts, and tails have both positive and negative properties. It’s not about cutting them in or out, it is about the flavor profile you want to high-light as a distiller, when producing a certain spirit!

A Framework for Managing Heads, Hearts, and Tails

First, decide what spirit you want to make and what the associated flavor profile is. Some examples? Here you go. Vodka aims for a minimal flavor experience at high purity, so you’ll want to cut out all heads and all tails. Less flavor, more purity, less toxicity. Whisky is flavorful and full bodied. Incorporate late heads and early tails, and only cut out the early heads and late tails. You’ll get all the flavor, while controlling – to an extend – overall toxicity levels. Fruit brandy? Fruity flavors are found in the heads, so cut out all the tails, and cut out only the very first bit of the heads.

Secondly, choose the right type of still. A potstill sucks at compacting heads and tails … and is therefor a great tool for whisky making, where you need both the late heads and early tails to smear into hearts. Bubble cap stills offer great defense against tails smearing, which makes them very well suited for fruit brandy production. iStills, with their elaborate control systems and automated cuts management, can make any spirit to perfection.

Thirdly, please understand that low and high boiling point alcohols (and their associated flavors) are developed during fermentation, not during distillation. Distillation is simply a way to control them. In other words: if you want to create a certain flavor profile, for a certain product, with a certain still, well, it actually all starts with your fermentation protocols! If you ferment in such a way that no flavors and no toxic alcohols are formed, you are already almost at vodka level purity, even before starting-up your still. That is great if vodka was your goal, but not so good when making whisky. The opposite holds true as well: a flavorful ferment is a great base for whisky making, but not for vodka production.

The fourth step should actually be the first step. Learn more about still design, about spirit flavor profiles, about how fermentation influences heads, hearts, and tails production. Learn more about cuts. Where? At the iStill Distilling University. For more information and registration, contact Veronika@iStillmail.com.


Odin on Still Design!


This iStill Blog post is about my take on design. Not so much the technicalities of how to manage vapor speeds, reflux amounts, temperature delta’s, and cut points, but – on a deeper level – my focus on the starting points and assumptions that underpin how I think, when solving an issue via a new design.

In this article I’ll try to articulate my design assumptions and the guiding principles I design by. Then I’ll put them in the context of how I design iStills specifically. Finally, I’ll share examples of how deviations from certain design principles can lead to poor still designs.

Starting points

The following base assumptions guide the way in which I design:

  1. Follow the science, debunk the myth
  2. Think inside-out
  3. The best solution to any problem is not to have a problem
  4. Less is more
  5. Integrate functionalities
  6. Bottle-neck management

Follow the science, debunk the myth

When designing, one intends to make a structural solution for a problem or challenge that continuous to pop-up. In still design, the challenge is to manage the distillation process in such a way that affordable, predictable and repeatable outcomes in terms of spirit quality and quantity are achieved. In designing the iStill, the goal was to take the guessing out of the craft distilling process via improved still design.

There were many existing opinions on still design, simply because the whole industry was struggling massively to achieve affordable, predictable, and repeatable outcomes, before we entered the market. If one found something that worked, even if only partially, what was found provided a solution. If this solution helped you make sense of it all, maybe that solution could help others? Sometimes, yes, but often not. Often, the solutions found were based on assumptions that are wrong. We need science to debunk the myths and to help migrate us to a better understanding of what distilling is really about.

An example of an incorrect assumption that misguided many in the industry? Here you go: many distillers, that migrated from a potstill to a plated still, found that their spirits would become less tails-oriented in flavor-profile. Since potstills do not have cooling management (to create reflux higher-up in the column), but plated stills do, the assumption was that it is the cooling management that prevents early tails smearing and its associated third dimensional flavor characteristics. Our scientific research proved that it is the fixed liquid baths on the bubble-cap plates that prevent early tails smearing from happening, not the cooling management. Debunking the myth, and replacing it with scientific knowledge, allows me to design stills that takes advantage of an improved understanding of the actual science of distillation. Concretely? Our plated column allows our customers to manage early tails smearing much better than traditional plated still designs are capable of, simply because we identified the root-cause and designed a solution accordingly.

Another great example on how anecdotal “knowledge” can result in bad still design is Mr. Mueller’s Aromat column design. Mr. Mueller, like many in the industry, believes that flavor benefits from copper contact. So he designed a long, complex copper column in order to boost copper contact. Scientific research teaches us that copper does not add beneficial flavors, but that it merely catalyzes bad sulfuric compounds that originate from poor fermentation management. Yes, sulfuric beer or wine will improve from copper contact, but via deduction, not addition. More copper, as in the Mueller Aromat, just translates into a more expensive, difficult to manage and almost impossible to clean “solution”, that results in copper contaminated drinks, rather than better tasting spirits.

Think inside-out

High quality distillation control is all about managing the speed of rising vapors, influencing the quantity of falling reflux, and creating the medium for gasses and reflux to meet and mingle. Where do those processes take place? They all take place inside the distillation machine. So if you want to optimize vapor speed control, reflux quantity, and gas/liquid phase control, you need to think from the inside-out! It is a perfect design of the internals of the distillation machine, that make it a world-class performer. The outside follows the inside, as “form follows function”. That’s what we do, but that’s not what others do. The lack of understanding of the science of distillation leads to an outside-in perspective on traditional still design. Allow me to give you an example.

Traditional stills, that are made from copper, are not insulated. Insulation results in more control over vapor speeds and reflux quantities, so for us it is a no-brainer to add it. But, hampered by a lack of understanding, and a focus on looks, traditional manufacturers choose to show the uninsulated copper, “because it is beautiful”. If a beautiful machine limits your potential to make better spirits, our “form follows function” starting point is replaced by “function follows form”. The focus on the external shape has a negative impact on efficiency, flavor composition and control.

Uninsulated columns lead to variability of outcome. Sight glasses hamper the flows of gasses and reflux, without the distiller gaining any actual insight. It is the outside-in approach to design that cause issues, where an inside-out approach to design solves problems. Inside-out thinking leads to more control over flavor composition, increased repeatability, better quality, at lower overall production costs.

The best solution to any problem is not to have a problem

Most designers make structural solutions to counter structural problems. Often, they assume a problem is structural. Great! As the designer identifies a reoccurring problem, he can get to work on a solution to fix that problem. But you know what would be really great? Investigating if that problem is actually structural to start with. Why? Well, simply because of this: if it turns out that the encountered problem isn’t structural, then maybe no structural solution is needed. The best solution to a problem is fixing the problem, rather than designing a solution to counteract that problem.

Do you remember how copper stills catalyze sulfuric compounds that may have developed during fermentation? Copper stills are a structural solution for a non-structural problem. The best way to prevent sulfur contamination is to invest in fermentation control. Well-controlled fermentations prevent sulfur contamination from developing. Fermentations without sulfur contamination do not need copper as a (expensive and toxic) solution. Do you start to see how the best solution is not to create the problem to start with? The best solution to any problem is fixing the problem before it arises. Copper is a medicine for a bad ferment, so, dear craft distiller, please get your act together, and start controlling your fermentations! It is where your alcohol and flavors are formed. What can be more important than that?

Less is more

If a problem is structural and does need a designed solution, let’s design that solution from a perspective of “less-is-more”. The easiest and simplest solution to a problem is usually the best solution.

Another copper-related example? Here you go. Let’s say that for an existing distillery it simply isn’t possible to add adequate control to their fermentations. As a result they might end up with sulfur infected distillers’ wine or beer. Now, based on the knowledge that copper catalyzes sulfur, a copper column may be suggested as the best solution. But is it the best solution?

If we drill down on the issue of sulfur contamination, what’s needed is vapor to copper contact. We need, in other words, a large copper surface area in that part of the still where gasses travel through. Yes, a copper column does provide exactly that, but calling a copper column a simple or easy to operate solution would go a bit far. Yes, it is a solution. Yes, it creates a whole new set of problems. A “less-is-more” perspective allowed us to design the copper waffle. It offers the required surface area and it sits in the gas stream. It mitigates the need for the extensive cleaning protocols, that copper columns have. It sits low in the column, thus preventing copper particle contamination. And if it wears out, you just purchase a new affordable waffle instead of a new expensive column.

A great non-copper example of this design principle is the aforementioned cooling management that so many traditional plated stills offer. “Cooling management” means that, by managing the cooling water flow, the craft distiller can create bigger or smaller amounts of reflux. Even though cooling management was a great invention a century and a half ago, it did (and does) come with a set of disadvantages: since water temperature, pressure, and the delta between water temperature and the distilling hall vary significantly during a day, it becomes difficult to replicate results. There are too many confusers.

Our solution? We have invented liquid management as a means to regulate the amount of reflux generated. By cooling all gasses back down to liquid state before deciding what amount goes out of the still (as spirits) or back into the column (as reflux), all of the confusers are dealt with. Water pressure, temperature, and the delta in temperature between the coolant and the distilling hall no longer bear any impact on product quality and quantity!

Integrate functionalities

If we look at still design as a series of challenges or problems that need to be solved by one machine, that machine by definition will have various solutions integrated in its overal design. A heating system heats up the wash, an agitator mixes the wash, an air-vent prevents potential pressure build-up, a CIP allows you to clean the column with ease, and a hoisting-eye allows the craft distiller to assemble or disassemble his still without too much hassle.

In a way, a still can be seen as a combination of various designs that, together solve all the issues related to distillation. Each little design solves its own little problem. But this standard approach to design, where complex machines are a combination of various little solutions for many little problems, is far from ideal. It creates sub-optimization. I strongly believe in synergy via the integration of various functions. Allow me to give you a few examples, based on the micro-solutions presented in the above paragraph.

Yes, a heating system heats up the wash and brings it to a boil. But by simply making the heating system variable or proportional (think: power management), it adds a huge benefit: control over vapor speeds! Integrative thinking resulted in the heating system now having two functions instead of one. It resulted in control over smearing, flavor, cut-points, and yield.

Yes, an agitator mixes the wash and prevents scorching. But by simply making the agitator system variable or proportional (think: control over agitator speed), it adds a huge benefit: control over inner-boiler temperature differences, resulting in more or less Maillardization and up to 25% more (or in the case of vodka: less) flavor. Again, integrative thinking allowed us to design an agitator system that has two functions instead of one. It has resulted in control over Maillardization, which has given our customers a tool to boost their flavor intensity with 25%. How’s that for a competitive advantage?

A pressure-release valve helps prevent potential pressure build-up. A CIP makes cleaning the column easier. A hoisting-eye makes for easier still assembly and disassembly. Most stills have a pressure-release valve. Many have a CIP. Almost none have a hoisting eye. Not only does iStill have all three functionalities, we were actually able to integrate those three solutions in one design, in one part. An integrative perspective on design allows us to have one part do different things. This results in a simpler, more affordable, and easier to operate machine.

Bottle-neck management

Most look at design as a single step in the overall production process. First, a design is made. Then that design is produced. If it works, no design-changes are done and production keeps on going. No improvements, no changes, let’s keep selling and producing. If it is good enough, it is good enough. Redesigning things costs time and money!

I beg to differ. Design is never done. Design is an iterative process that continuously improves functionality. Every design change does not only offer an improvement of the primary functionality that part performed. As that part’s performance changes, the complete system’s performance is offered a potential boost. How? By looking at bottle-necks.

A bottle-neck is the primary constraint on any design; the “thing” that prevents it from improving its core design goal. In a race car, for instance, that aims to go around the track as fast as possible, the constraint can be the engine (not powerful enough), the tires and brakes (not enough grip), or the quality of the driver (who does or doesn’t get the maximum out of the package he is offered).

If a faster distillation run is needed, bigger heaters can be installed. But if the still is uninsulated, most of the added power will result in a warmer distilling hall, not in faster production rates. If “speed” was the goal, then “power” was not the bottle-neck. If a lack of speed needs to be addressed, find the constraint, find the bottle-neck.

I remember doing a vast redesign on the early NextGen columns. It would facilitate a 40% boost in performance. When we ran the tests, we couldn’t find more than a 5% gain. What was wrong? It turned out that the newly designed column was so fast that it introduced a new bottle-neck: air-pressure equalization just couldn’t keep up. Now having found the new bottle-neck, we could simply increase the air-pressure equalization’s through-put and there it was: the 40% boost in performance we were looking for!

Design is never finished. Fine-tuning always continuous. Structurally and via software, and always retrofittable to existing machines. It turns the iStill into the only still that actually gets better with age. How’s that for future-proofing your craft distillery?


Send us your medals please!

iStill distilleries win important medals all over the world. We are designing a web-page for our medal-winners to shine: the iStill Hall of Fame!

So here’s an invitation: please email us a picture of your spirits and the medals it has won! Via Esther@iStillmail.com. We’ll make sure your rewards get the attention they deserve.


Become a Listoke Distillery Owner!

Who are you? Can you tell us a bit more about your background?

Bronagh Conlon – nurse, midwife, jam maker and now gin maker! I am the founder and owner of Listoke Distillery and gin school in Co. Louth Ireland.

I love a challenge and I always look and think outside the box – thus our latest fund raising escapade of a raffle for part of my amazing distillery!

Bronagh Conlon, Listoke’s Master Distiller …

Bronagh Conlon, Managing Director Listoke Gin School pictured at the Company’s Tinure, Co. Louth Distillery yesterday. PIC COLIN O’RIORDAN

What’s Listoke Distillery? And can you tell us a bit more about its philosophy?

Listoke distillery was set up in 2016 with an iStill 50 litre and then an iStill 500. We are now in our new distillery and Gin School – Ireland’s first and best gin school – and have an iStill 2000. We make premium award winning gin and have just launched our Wise Owl Whiskey (WOW).

How was it to start-up? How are things now?

We set up to make gin and then tried the option of the gin school which has really put us on the gin map for tourism and events. Following dusting down from Covid – though we are still making sanitizer – we have re-focused on our exports to the US and further expansion there and Russia with our Cacao & Raspberry pink gin and our Wise Owl Whiskey. We are also just in the process of launching all three products into the Chinese market with a distributor being signed up.

Why did you choose iStill? How were they involved and why was this important to Listoke?

Odin and Veronika have been part of our journey from the very beginning. We were not initially looking at whiskey so we needed the best equipment possible to ensure our gin was the best possible and that meant an iStill.

We love our iStill family – including Odin and Veronika – but especially our baby 50 litre,  mammy 500 litre and the boss – 2000 litre. We love to show them off during our distillery tour and explain that our iStill’s “are an iPhone version of a dial up still!!

We can ensure consistency, quality and reliability in every batch we make either for ourselves or for a small corporate run. We are very proud of our super premium quality and the flexibility is exceptional.

Why the raffle? Who can join?

We always think outside the box. There are many people who would just love to be a distillery owner  – also, imaging a life time supply of gin- and they can for less than the price of a bottle of gin!!

We are holding the raffle of 5% of Listoke Distillery to help raise funds for our brand activation in China and the US. It’s a novel option for us, but a massive opportunity for someone to be a part of our buzzing family business and to enjoy the ride with us.

At present the 5% is valued at €85,000 however, we are only starting. The lucky winner will be part of Listoke, can make their own gin, attend the gin school and be our top gin taster! There is also a second prise of £10,000 and a third prise of £5,000.

For whom is the raffle and how can they reach you?

I think that anyone with an interest in gin, distilleries and the general 28-+ age group who would just like bragging rights and enjoy free gin!

For more information on how to potentially become a Listoke Distillery owner, please reach out to Bronagh@ListokeDistillery.ie or see the following link:


Listoke’s Gin School (psst … you can see the iStill 2000 via the first window to the left) …