Liquid Management for Better Quality Spirits!


Managing the distillation run is crucial for craft distillers, since it helps control flavor composition and concentration of the spirits they produce. This post dives into the technologies available. We distinguish between power management, cooling management, and liquid management.

Power Management

Power management is the simplest way to manage your still and distillation run. If you want to go faster, you just crank up the power. Throw more wood on the fire. Open the gas tap. Feed more kilowatts to your still.

Increased power results in more gasses being created, leading to a faster run. It also results in more smearing. More heads and tails molecules will enter your hearts cut. More fruity as well as rooty and nutty flavors will be added, resulting in a more complex product. A more complex product that needs longer time to age to maturity.

If you decrease power, the run slows down. Slower runs mean less smearing. Cleaner, crisper spirits are produced, that do not need a lot of aging.

Power management is the only management technology available to pot distillers. A potstill doesn’t have an actively managed column, so power management is the only management tool the distiller has to influence his spirit’s flavor profile.

This technique is as old as the potstill itself. How old? Thousands of years. Power management is an easy, yet crude way to manage your distillation run. Smearing always takes place. Reproducibility is difficult, unless your still is fully insulated, to minimize for outside influences.

Cooling Management

The 1870’s saw the invention of cooling management, the first technology that allows for not just the pot, but also the column to be managed. Power management manages the pot. Column management manages the rising gasses as they come from the pot.

The way in which cooling management does this is as follows: as gasses rise, part of them are cooled back to liquid phase and redistilled on plates in the column. The additional distillation cycles on those plates result in a higher proof and a better separation of heads, hearts, and tails. The cooling is done by a heat exchanger 2/3rds up the column. The heat exchanger is called a dephlagmator or dephlag.

Adding more coolant to the dephlagmator results in more gasses being cooled down to liquid phase. More liquids or reflux created contributes to more distillation cycles taking place and less smearing of heads and tails into hearts. Limiting the amount of cooling water to the dephlagmator results in less distillation cycles and more smearing.

Adding column management to a still was a huge step forward. You can look at it like this: power management creates a crude form of input management where column management creates a form of output management. Power management defines what enters the column or riser. Cooling management gives a crude selection as to what portions come out of the column and make it over into the drink you are producing.

Even though two management techniques are better than one, cooling management comes with draw-backs. The amount of control it gives is limited, because of four confounders:

  1. The temperature of the cooling water varies;
  2. The water pressure varies;
  3. The temperature in the distilling hall varies;
  4. Air pressure varies.

Warmer cooling water in (e.g.) the summer results in less reflux and less redistillations and more smearing. A higher water pressure during some parts of the day results in more cooling and in less smearing. The colder distilling hall leads – in an uninsulated column – to more reflux being generated, resulting in less smearing, less fruity and rooty flavors in your hearts cut. High pressure weather fronts lead to different (higher) boiling points of the various distilled factions, resulting in a slower run with better separation between cuts.

Liquid Management

iStill introduced liquid management to the distilling industry 10 years ago. With this invention, we aimed to perfect column management, and to get rid of the imperfections caused by the 1870’s cooling management technology, that we addressed above.

Liquid management is not influenced by temperature variability of the cooling water. Is the coolant warmer or colder? Our liquid management technology doesn’t care. It simply delivers the same product quality over and over.

Liquid management is not influenced by water pressure. Again, iStill’s liquid management technology doesn’t care and simply delivers a totally consistent output, over and over again.

Is your distilling hall warmer in the summer and colder in winter? Given the insulation we use, there is no impact, so no variability. Again, with liquid management the craft distiller can consistently deliver high-quality spirits.

Air pressure variability? iStills column management measures the actual air pressure on a second-to-second basis. If the air pressure changes, the cut points are automatically adapted. There you have it again: total control over flavor composition and concentration.


For the craft distiller to produce his spirits at the highest quality level possible, and to do so consistently, liquid management is needed. Craft distillers do not enjoy the economies of scale that Big Alcohol has. This means that craft distilled price levels will be higher. To compensate for this disadvantage, the quality of your drinks needs to be higher. It takes iStill’s liquid management technology to get you there.

I expect this post to clarify how we help revolutionize (and energize!) the craft distilling industry. And it also helps explain why so many of our customers win medals all over the world! See the link for a selection:

iStill University Certified Master Distillers Training!


There are only two spots left available. Do you want to become a Master Distiller? Follow our online course and reach out to to reserve your place!


After over a year of not being able to give on-site trainings at iStill HQ, we are proud and happy to announce we are opening up again! The iStill Distilling University organizes the Certified Master Distillers Training at iStill HQ.


The iStill University Certified Master Distillers Training takes place from October 4th till October 8th, in Woerden, at iStill HQ, located under Amsterdam, at around 30 minutes from Amsterdam Schiphol Airport.


The Certified Master Distillers Training is a practical training, where we train you how to make brandy, gin, rum, vodka, and whisky, as well as liqueurs. The focus is on “learning by doing”. You’ll spend as much time as possible behind the iStill Mini to make a variety of spirits, and to learn how to manage your still as well as how to make perfect cuts. Mashing and fermenting, and runs on the bigger iStills will also be part of the curriculum.


The Certified Master Distillers Training picks up where the iStill Certified Craft Distilling courses stop. The Craft Distillers course teaches you the theories around distilling, where the Master Distillers course focusses on hands-on training. The Certified Craft Distillers course is theoretical, the Certified Master Distillers Training is practical.

In order to participate at the Certified Master Distillers Training, you need to be a Certified Craft Distiller already. We need everybody to be on the same page, on the same theoretical knowledge-base, before we can dive in deeper via the Certified Master Distillers Course.



·      Welcome

·      Theory of distillation recap

·      Smelling all alcohols

·      Filling the iStill Mini with wine

·      Fractioning the wine

·      Making cuts to turn wine into brandy

·      Watching brandy program on iStill 500


·      Theory of fermentation recap

·      Mashing 10 liters

·      Fermenting 10 liters

·      Organoleptic training overview

·      Visiting the windmill

·      Dinner


·      Feedback from day 1

·      Theory of extraction recap

·      Extraction on the Mini

·      Extraction on the i500

·      Creating hard seltzers

·      Sensory training: fruits and grapes


·      Creating a program on the iStill

·      Programming the iStill

·      Cleaning the iStill Mini

·      Distilling vodka on the Mini

·      Distilling vodka using ABV-C


·      Feedback from day 2

·      Turning extracts into liqueurs

·      Turning extracts into essences

·      Finishing run: vapour speeds


·      Sensory training: botanicals

·      DIstilling gin on the iStill Mini

·      Sensory training: faults

·      Visiting Rummiclub Distillery


·      Feedback from day 3

·      Sensory training: wood

·      Cleaning the iStill Mini

·      Distilling rum frow low wines

·      Aging spirit with heat and oxygen

·      Aging spirit with ultrasound

·      Using wood chips for aging


·      Distilling fermentation on the iStill Mini

·      Sensory training: aged spirits

·      Measuring and diluting your spirit

·      Evaluation of the spirits

·      Food pairing theory

·      Graduation dinner


Participating at the Certified Master Distillers Training costs EUR 2.495,-. Two dinners and four lunches are included, as well as your certification.


Do you want to participate? Please know we maximize the number of students to 12. You will be working with the iStills Mini in groups of 2.

For registration, please email

Pre-Covid picture of the iStill Distilling University …

Less is More and More is Less!


More distillations for more purity, less distillations for less purity. How come? How does it work, and what are the pro’s and cons of adding more or less distillation cycles to your standard operating procedure? Let’s dive in deeper!

What a distillation cycle does

If you distill a beer or wine, there are basically three components in the boiler:

  1. Water;
  2. Alcohol;
  3. Flavors.

Since alcohol comes over at lower boiling points than water, as a general rule, a distillation run concentrates the alcohol. Most of the water remains in the boiler. Alcohol consists of a family of different molecules. Some have lower boiling points, some have higher boiling points. Ethanol, the most famous alcohol, sits in the middle, with a boiling point of 78,3 degrees Celsius. Many of the flavors come over with the alcohols, so a distillation run concentrates both alcohol and flavor, while water and some other flavors stay behind.

What multiple distillation cycles do

Multiple distillation runs translate into alcohol and flavor being concentrated even more. More water and more flavor stays behind.

It is important to note that certain flavors come over with certain alcohols. Fruity flavors come over with the low boiling point alcohols that come over during the first part of a distillation run. Rooty and nutty and earthy flavors come over with the high boiling point alcohols, at the end of the run.

The more distillation cycles are performed, the better alcohol and water are separated. Also, the more distillation cycles one does, the better the various families of alcohols separate. Ergo: more distillation cycles lead to less smearing of flavors and to more localized flavor concentrations. Fruity flavors in the headsy parts of the run, rooty, earthy flavors in the tails part of the run.

The influence on flavor

More distillation cycles lead to less flavor, via two processes:

  1. The boiler remains have flavors that are discarded after the run, and don’t come over in the spirit;
  2. Better separation leads to less smearing leads to less intense or less complex flavors in the hearts cut.

The more often the craft distiller distills, the more flavor he or she looses via the boiler remains, that will be discarded. The more often the craft distiller distills, the more the flavors will be localized in the heads and tails factions of the run. Instead of in the hearts faction that, well, makes the cut.

This information leads to one conclusion and one conclusion only: less is more and more is less. Less distillation cycles lead to more flavorful spirits. More distillation cycles lead to less flavorful spirits.

Spirit archetypes and the number of distillation runs

Vodka is distilled many times. Often more than 14 times, in order to reach the desired ABV. At the same time, the multiple distillation cycles lead not just to a high proof base spirit (95% and more), but also to a relatively neutral spirit. Perfect separation of heads and tails and their associated flavors. Water soluble flavors, that reside in the boiler, are perfectly separated out.

Bourbon, an American style whiskey, is often distilled around four times or more. On a plated still or on a continuous still. The result is a lighter style whiskey. Irish whiskey is most often triple distilled. It has a lighter flavor than Scottish single malt whisky, which is double distilled.

Most fruit brandies are made on plated stills and are usually quadruple distilled (yes, just like Bourbon is). Cognac is made on more traditional set-ups (Alambics Charantais – basically a potstill that uses the next batch as coolant) and is double distilled. Cognacs have a heavier flavor profile than fruit brandies.

Rums that are pot distilled, like Jamaican rums, are very heavy flavored. Rums that are distilled on a continuous column, including multiple distillation cycles, like Bacardi, are much lighter in flavor.

Distilling 1.5

Less than a decade ago, iStill’s CEO invented “Distilling 1.5” as a technique to lower the number of distillation cycles in order to give craft distillers a competitive advantage over traditional Big Alcohol producers. In the Distilling 1.5 procedure, a first distillation creates low wines. The low wines are added back into the boiler. To further fill the boiler, fresh wash is added. This mixture of low wines and fresh beer or wine now sees a finishing run.

Since the resulting new make spirit is now distilled 1.5 times instead of twice, more flavor is retained. First of all, less flavor is lost to the boiler remains. Secondly, the lower ABV end product needs less water (neutral!) for dilution to barreling or bottling strength.

Distilling 1.0 with iStill’s ABV Control

Over the last few years, iStill has innovated further on this idea that less is more. We have designed and perfected ABV Control, where the iStills can now bring your alcohol up to any desired percentage in one go. One Single Distillation Run! This is the ultimate “less is more” technique, where the craft distiller creates the most flavorful rums, brandies, and whiskies!

ABV Control ON!


Only a few years after Germany’s car manufacturers were held responsible for Diesel-Gate, do we now have German still manufacturers creating the next big deceit? Stills should work for many years, but that does not seem to be the case with German copper stills anymore. Does the craft distiller, purchasing a traditional German still get the required quality, or do these still manufacturers underperform in quality and material thickness?

An interview with Patrick van Zuidam, managing director and master distiller at Zuidam Distillers, by WhiskyPassion teaches us the following (translated from Dutch) and may serve as an example of how poor things have gotten:

“The sours and acids in the wash eat away the copper with each and every run, basically dissolving part of the still. Fortunately weak parts can be replaced. The copper in our lyne-arm was gone in just five years. The copper was, at some places, as thin as paper.”

Shouldn’t a still last longer than that? Here at iStill we strongly feel it should. But how can we hold other manufacturers responsible for delivering at higher quality levels? We can’t, but you can. All we can do is inform you. It’s the craft distillers that need to take it from here onwards.

It is High Time to End the Age of Steam!


The Age of Steam refers to a period in the industrial revolution of parts of Europe and North America, where steam was used as an energy source for production purposes. It started around the year 1770 and ended around 1914.

Yeah, the Age of Steam ended for the rest of the world, but close to 60% of the distilleries are still pushed into using steam to power their stills! That’s craft distillers using a technology that died out a century ago! Is it time to carry steam heating to its grave in the distilling industry? Hell, yeah! Long overdue! So let’s start going.

Two types of steam heating

There’s indirect and direct steam heating. An indirectly heated steam still uses steam to condense in the Au bain Mary / double walled section of the boiler. As the steam condenses back into water, it gives off energy that heats the inner boiler. It heats the boiler indirectly, because there is no direct contact between the heat source (steam) and the wash.

Directly heated steam stills inject the steam into the mash and thus heat it up. A steam generator is purchased that generates steam. The steam is bubbled into the wash that sits in a boiler. As the steam collapses back to liquid state, it heats up the wash, and brings it to a boil.

What steam heating really produces: problems for the craft distiller

Steam works under pressure and asks for rigorous certification. An additional tool is needed (the steam generator). Additional piping is needed (all certified to the extreme). It doubles or triples costs for the craft distiller. It doubles or triples the time it takes to build-up the distillery and go from plan to production. But that’s just the beginning of the issues.

Direct steam heating adds water to the wash, thus lowering ABV, where the goal (or at least one important goal) of distilling is to raise proof! You see the conflict of watering down flavor? Not a procedure that really benefits craft distillers in their fight with Big Alcohol via the production of more flavorful drinks.

Indirect steam prevents the craft distiller to take advantage of the Maillard Reaction. The Maillard Reaction adds up to 25% of flavor to craft distilled products. If craft distillers are to compete on flavor, well, you better make sure you have a still that allows you to Maillardize your boiler contents. Indirect steam heating prevents that, so it’s a no go for the craft distiller that wants to both optimize and maximize flavor profiles of their spirits.

“But steam allows you to warm up your boiler so quickly!” some say. Yeah, well, that’s complete BS. To heat up a certain amount of wash, a certain amount of energy is needed. Via steam or via electricity or via burning wood. But if you outsource a steam boiler, sure, buy a bigger one. The people that build traditional stills don’t mind. It is not their problem. If they knew what they were talking about, though, or had your market conditions in mind, they could have told you energy is energy. Here at iStill, we go above and beyond by asking an additional question: “Is a faster heat-up time in the boiler a pro?” Since taste formation benefits from longer heat-up times, why not heat up overnight, slowly, in order to create a more flavorful product? The craft distiller does not compete on yield or per liter costs with Big Alcohol. It competes on flavor!

Here’s the real reasons why steam stills are pushed onto the craft distilling industry

As a still builder, iStill wants to optimize heating (gas creation), gas manipulation, and liquefaction. Heating is an integral part to the distillation process that we do not outsource.

Other still builders love to outsource heating. First of all, it sorta lowers their still price. Their stills appear to be more affordable, because heating is not included. You still have to purchase it and it will be expensive, but that’s not their problem, but your problem. They simply build a shell still and you (or your architect or engineer) can go figure out the rest.

The other, more important reason why steam stills are still being sold, has to do with certification. As a still manufacturer that integrates heating in its solutions, iStill certifies for CE, UL, ULC, NZS, AS, ATEx, and IECEx. It costs a tremendous amount of effort and money to obtain and maintain these certifications. Our competitors (sic) don’t want the hassle and do not want to spend the money and effort. Instead, they point at the steam generator manufacturer. Or at you.

There you have the real reason why so much of the distilling industry is still residing in the Age of Steam, where it was terminated in other industries over a century ago: it helps the interest of traditional still manufacturers at the expense of your interests as a craft distiller!

Steam belongs in a museum, not on the work floor …

Optimizing Yeast Nutrition!


Yeast converts fermentable sugars into alcohol. Sugar levels, temperature, oxygen levels, pH, and nutrients in the yeast’s environment all play an important role. Today, we investigate nutrition. Healthy yeast creates a higher yield and a faster ferment. So let’s dive in deeper and find out what nutrients it needs in order to perform!


Why does yeast need nutrition? Doesn’t it come fully functional? It does, but – just like you and me – yeast needs nutrients to keep going. And there is more. Yeast, in an oxygen-rich environment, so especially at the beginning of your fermentation cycle, multiplies. One yeast cell becomes two, then four, then eight, then sixteen, etc. Without additional nutrients, the available nutrition would have to be divided between more and more cells.


Yeast Assimilable Nitrogen (YAN) is very important. During the first 72 hours of your fermentation, the yeast will absorb it. During the fermentation, YAN is used to synthesize proteins, amino acids, other building blocks, that are essential to the yeast and its ability to produce alcohol.

A lack of YAN leads to an increased production of glycerol at the cost of alcohol production. YAN deficiency can decrease total alcohol yield by up to 10%. Put differently, by adding enough nitrogen, the craft distiller can potentially increase his yield with 10%!

But there is more. A lack of YAN also results in less esters and acids being formed. If you are educated in Odin’s Theory of Fermentation, you will immediately understand that this is bad for overall flavor development.

The optimal amount of nitrogen is 267 mg per liter. Amounts below 140 or above 400 mg per liter will result in non-optimal outcomes. The yeast may stall and stop producing alcohol all together.

To prevent such a situation from developing, add 0.6 grams of di-ammomium Phosphate (DAP) per liter.

Zinc sulphate

Zinc sulphate is another essential nutrient to yeast growth and performance. The yeast cells use it to grow. It is also a source of energy, via the production of NADH and NAD+. and it increases alcohol tolerance. Off the yeast, not of the consumer. 😉

Zinc improves the production of ethanol. Zinc ions help the yeast create vitamine B2, essential to yeast growth.

Zinc sulphate is absorbed during the first 48 to 96 hours of the fermentation. An ideal level is 0.4 mg per liter of fermentation. Values above 0.6 or below 0.1 mg per liter will result in the yeast stopping to function.

Add 0.0004 grams of zinc sulphate per liter.

Copper sulphate

Copper ions and zinc ions can react and form a superoxidedismutase. That word helps you win at Scrabble. It is also an enzyme that catches biradical oxygen atoms, that are toxic to the yeast, and turns them into O2, oxygen, which is exactly what it needs.

Copper ions help induce metallothioneïnesynthesis, which helps bind heavy metals, that would otherwise harm the yeast cell. It is also essential to the yeast’s metabolism and growth.

Add 0.001 grams of copper sulphate per liter.


Mash or otherwise mix substrate with water. Bring the mix to fermentation temperature. Add the above nutrients and mix them in. After that, add the yeast.

For more reading

Please see:

1.        Asif, H. K. et al. Comparative study of bioethanol production from sugarcane molasses by using Zymomonas mobilis and Saccharomyces cerevisiae. African J. Biotechnol. 14, 2455–2462 (2015).

2.        Arroyo-López, F. N., Orlić, S., Querol, A. & Barrio, E. Effects of temperature, pH and sugar concentration on the growth parameters of Saccharomyces cerevisiae, S. kudriavzevii and their interspecific hybrid. Int. J. Food Microbiol. 131, 120–127 (2009).

3.        Mendes-Ferreira, A., Barbosa, C., Lage, P. & Mendes-Faia, A. The impact of nitrogen on yeast fermentation and wine quality. Cienc. e Tec. Vitivinic. 26, 17–32 (2011).


5.        Albers, E., Larsson, C., Lidé N, G., Niklasson, C. & Gustafsson, L. Influence of the Nitrogen Source on Saccharomyces cerevisiae Anaerobic Growth and Product Formation. APPLIED AND ENVIRONMENTAL MICROBIOLOGY 62, (1996).

6.        Mendes-Ferreira, A., Mendes-Faia, A. & Leao, C. Growth and fermentation patterns of Saccharomyces cerevisiae under different ammonium concentrations and its implications in winemaking industry. J. Appl. Microbiol. 97, 540–545 (2004).

7.        Pretorius, I. S. & Henschke, P. A. Title: Influence of diammonium phosphate addition to fermentation on wine biologicals Mar Vilanova [1].

8.        Brice, C., Sanchez, I., Tesnière, C. & Blondin, B. Assessing the mechanisms responsible for differences between nitrogen requirements of saccharomyces cerevisiae wine yeasts in alcoholic fermentation. Appl. Environ. Microbiol. 80, 1330–9 (2014).


10.      Zhao, X.-Q. & Bai, F. Zinc and yeast stress tolerance: Micronutrient plays a big role. J. Biotechnol. 158, 176–183 (2012).

11.      Zhao, X. Q. et al. Impact of zinc supplementation on the improvement of ethanol tolerance and yield of self-flocculating yeast in continuous ethanol fermentation. J. Biotechnol. 139, 55–60 (2009).

12.      Raj, S. B., Ramaswamy, S. & Plapp, B. V. Yeast alcohol dehydrogenase structure and catalysis. Biochemistry 53, 5791–803 (2014).

13.      De Nicola, R., Hall, N., Melville, S. G. & Walker, G. M. Influence of Zinc on Distiller’s Yeast: Cellular Accumulation of Zinc and Impact on Spirit Congeners. J. Inst. Brew 115, (2009).

14.      De Nicola, R. & Walker, G. M. Zinc Interactions with Brewing Yeast: Impact on Fermentation Performance. J. Am. Soc. Brew. Chem. 69, 214–219 (2011).

15.      Šillerová, S. et al. Preparation of Zinc Enriched Yeast (Saccharomyces Cerevisiae) By Cultivation With Different Zinc Salts. J. Microbiol. Biotechnol. Food Sci. 2019, 689–695 (2019).

16.      Priest, F. G. & Stewart, G. G. Handbook of brewing. (CRC/Taylor & Francis, 2006).

17.      Vecseri-Hegyes, B., Fodor, P. & Hoschke, Á. The role of zinc in beer production. Acta Aliment. 35, 17–24 (2006).

18.      Walker, G. M., De Nicola, R., Anthony, S. & Learmonth, R. Yeast-metal interactions: impact on brewing and distilling fermentations.

Yeast Cell Division Caused Nutrient Deprivation …

We invented a way to purify your heads and tails!

Willem’s Miracle Powder

Making careful cuts for hearts, leaves you with heads and tails losses. Well, here is the good news: as of today they are losses no more! iStill’s chemist Willem has tested a powder and designed a purification protocol, that will help you clean up your heads and tails to the extend that they will become your purest vodka or GNS. Want to learn more? Yes, you do, so let’s dive in deeper!

The Goal

Heads and tails are full of flavors. Mostly off-flavors, and that’s why you cut them out. But a deeper analysis learns us that the vast majority of those heads and tails are actually … hearts. Good ethanol, contaminated by small fractions of actual lower and higher boiling point alcohols and their associated flavor molecules aka esters.

The goal of Willem’s Miracle Powder? To recover this ethanol, but to get rid of the bad alcohols and bad flavors. Now, redistilling heads and tails during a vodka program on the iStill does a great job at getting rid of the bad alcohols. But the compaction of heads and tails, leads to the associated bad flavors to leach into the ethanol recovery.

Again, the goal of Willem’s Miracle Powder and this new procedure? To destroy the esters found in your heads and tails factions.

The Thought Process

If you have followed the iStill University, you have learned all about esterification and how flavor molecules are formed. You remember Odin’s Esterification Formula? And how a low pH results in more flavor molecules or esters being created?

Guess what, the opposite is true as well! If you make your heads and tails factions very alkaline, instead of acidic, you can destroy the alcohol-carbon bonds that make up the ester molecule. Treating your heads and tails factions and then distilling it in vodka mode, breaks up the esters, recovers the ethanol, and helps you turn what was a loss into the purest vodka or GNS possible.

The Procedure

  1. Add your heads and tails faction to the iStill;
  2. Dilute the heads and tails faction to 30% ABV;
  3. Add sodium hydroxide (0.4 grams per liter of diluted heads and tails faction);
  4. “Sodium hydroxide” as in caustic soda, also used by breweries to clean their stainless steel brewing equipment;
  5. Mix the sodium hydroxide in (be careful, this is not the stuff you want to inhale or get in touch with!);
  6. Start the vodka program;
  7. Choose the heads stabilization program to be at least 60 minutes;
  8. Distill as per usual;
  9. Toss heads and tails, keep hearts – the most neutral and delicious vodka;
  10. Treat the boiler content with citric acid to bring pH back to 7;
  11. Drain your boiler and rinse the system with water.

The Results

The results of the above procedure are amazing. The worst heads and tails turn into a beautiful vodka or GNS. That’s not just our opinion, but a scientific fact. Do you want to see some of the proof?

A chromatographic overlay of a 1% ethyl acetate solution (a heads faction) in purple, a 0.1% ethyl acetate solution in yellow, an untreated heads sample in green, and the black line (look careful!), that signifies the heads sample after treatment with Willem’s Miracle Powder (aka sodium hydroxide):

The above chromatographic analysis proves that iStill’s Heads & Tails Purification Procedure successfully removes the associated headsy esters from a heads (the graph title mistakenly says “hearts”) sample.

But that is not all! How does the procedure do against other heads and tails flavors? Well, here is the outcome of further CG analysis. In purple you see the various esters available in an untreated heads and tails sample. The black, line that is significantly lower, represents the ester count after the purification procedure:

But that is not all! This procedure, since you basically use a cleaning agent, also makes your boiler shine as if it were new.

The Conclusion

iStill’s Heads & Tails Purification Protocol works a charm. It allows the craft distiller that possesses iStill equipment to process former heads and tails losses and turn them into the purest vodka or (reusable) GNS.

Still Design: Why Air Resistance Matters!


Air resistance is important when designing a car or parachute, but for a still? Really!?! Yes, it is. Distilling is all about managing and manipulating the vapors that rise from the boiler. The amount of resistance, that the rising vapors encounter, influences the speed of those vapors. And vapor speeds define flavor composition.

Okay, maybe we should call it vapor resistance, rather than air resistance, but it got your attention, right? And it is basically the same thing. Interested to learn more? You better be. Managing vapors successfully is what is required to become recognized as a skilled distiller, so let’s dive in deeper.

Cuts for flavors

Have you ever noticed how a fast stripping run isn’t ideal for making cuts? How, for your cuts to work out, a lower power setting usually works better? Cutting is about the master distiller deciding what flavors should be in the spirit and what flavors should be cut out.

Heads, hearts, and tails

As we saw in an earlier iStill Blog post, flavors associate with heads, hearts, and tails (for more reading, please see: Fruity flavors come over during the beginning of the run, followed by the hearts-associated substrate flavors. At the end of the run the earthy and rooty tails-associated flavors come over.

Since, during the distillation run, the original alcohol charge in the boiler is slowly depleted, the rising vapors will become less alcohol rich and more water dense. As a result the temperature of the gasses increases (water boils at higher temperatures than alcohol). The iStill takes advantage of this by having an extensive control and management system in place, that allows the distiller to cut consistently each and every time, given a certain power setting. It is the “given a certain power setting” part that I now want to draw your attention to.

Vapor speeds, separation, and smearing

Our stills are insulated. Therefore an increase in power results in the creation of more gasses and more product per minute or hour. Since the column and boiler are structural parts that do not all of a sudden change shape or size, that column – with a power increase – needs to process more gasses. A higher power setting will result in higher vapor speeds in the column.

Low boiling point alcohols (and their associated fruity flavors) come over during the early part of the run. They need relatively low energy settings to boil off. High boiling point alcohols (and their associated rooty, nutty, and earthy flavors) come over later in the run. These molecules need relatively high energy settings and higher vapor speeds to come over.

With the above in mind, now imagine that we do a slow run. The headsy factions boil off first, since they need the lowest amount of energy and the lowest vapor speeds to come over. When almost all the heads is gone, the transition towards hearts collection takes place. And when almost all the ethanol (and its associated substrate flavors) is gone, the tails slowly and gradually blend in.

Now imagine a fast run instead. A high power setting results in higher vapor speeds. The higher vapor speeds push hearts and tails into the first faction of the run. As a result heads aren’t separated and depleted. During a very fast run, like a stripping run, the whole batch is smeared and tainted with heads, hearts, and tails. No separation, so not a great flavor. Quick and dirty. Do you see how vapor speed is essential to the amount of heads and tails we smear into hearts, and therefore how essential vapor speed is to flavor composition? If you do, let’s continue with the next chapter!

Vapor resistance hampers run consistency

Consistent vapor speeds are essential for consistent flavor harvesting, which is essential for consistent spirit production. You want your whiskey, rum, or gin to taste the same, each and every production run, right? Resistance in the vapor path not only leads to inefficiencies, it also results in vapor speed fluctuation. And if you have read the above paragraphs carefully, you now understand that vapor speed fluctuation is basically the same as flavor fluctuation. Flavor fluctuation prevents the craft distiller to produce high quality spirits consistently. Hence our efforts to design stills with the lowest possible internal vapor resistance. The less vapor speeds fluctuate, the less flavor fluctuation you’ll experience in the drinks you produce!

This is why air resistance matters. Resistance creates vapor speed fluctuation. Vapor speed fluctuation creates flavor inconsistency. Flavor inconsistency equals poor (or at least: suboptimal) quality. Poor quality impacts the craft distilling industry at large, and your personal business specifically. Poor quality destroys reputations as well as bottom-lines.

Do you want to become a better craft distiller? Do you want a better reputation and a better bottom-line? Control your vapor speeds. And ask your equipment supplier what he has done, design-wise, to give you that control. “What did you do to prevent vapor resistance?”, “How does the technology you provide limit vapor resistance as much as possible?” are legitimate questions any still manufacturer should be able to answer. Only they don’t and they can’t. We do, and here are some examples of how iStill gives you total control over vapor speeds and associated flavors via vapor resistance reduction.

Wide boiler design

Given a certain boiler charge volume, a still designer can decide to make a tall and narrow or a lower and wider design. A tall and narrow boiler dissipates its energy over a limited surface area. As a result the boil-up will be higher, creating turbulence in the vapor bath above the liquids. This inner-boiler turbulence results in the column or riser being fed with vapors at speeds that continuously change. The constantly changing vapor speeds in the column result in more smearing of heads and tails into hearts, and in less control over the exact amount of smearing.

A wider and lower boiler gives a much larger surface area (square root function!) for vapors to boil off from. As a result, there is less boil-up, and less turbulence. The column can now draw the vapors from a more stable gas bed, at steady speeds. Steady speeds result in less smearing and more control over the amount of smearing! iStill has a wider and lower boiler design, specifically for that reason.


An uninsulated column creates a temperature difference between the outside and inside of that column. The colder environment cools the column. The cooler column liquifies rising gasses into (passive) reflux. This is more than just an inefficiency, because it also creates inconsistency.

An uninsulated column or riser results in passive reflux. Gasses that normally should have come over as product now fall back into the boiler. The colder the climate (or distilling hall) is, the more inefficiencies are introduced.

But an uninsulated column or riser is also a variable that boosts inconsistency. Cooler columns lead to more passive reflux and lower overall vapor speeds. Lower vapor speeds may make it difficult to create the right amount of smearing, for a certain product category. When the climate or temperature in the distilling hall changes, a bigger or smaller temperature differential establishes, resulting in lower or higher vapor speeds, and less control over flavor harvesting and reproducibility.

iStill insulates its columns to minimize the temperature difference outside and inside the column. A low to non-existent temperature difference leads to a more efficient run (less passive reflux), stable vapor speeds, and reproducible and consistent outcomes.

Inner column design

Let’s compare iStill’s perforated plate still with a traditional bubble-cap fruit brandy still. The traditional bubble-cap column has plates that hamper vapors, where our design allows vapors to pass through. Fruit brandy stills have sight glasses that stick out, generating vapor resistance in the column.

Traditional stills have dephlagmators that cool part of the gasses back to liquid state, depending on cooling management, coolant pressure, and coolant temperature, air pressure, and the differential between inner and outer column temperature. Their dephlags are designed with a limited number of through-tubes.

iStill designs its coolers with a maximized number of through-tubes. More surface area creates less turbulence. Less turbulence results in steady vapor speeds and consistent flavor profiles.

iStill doesn’t use dephlagmators and cooling management, but instead invented the column cooler and liquid management. These innovations have taken variables that influence resistance and vapor speeds out of the equation. Coolant pressure, temperature, air pressure, and the difference between inner and outer column temperatures no longer screw things up.

If you didn’t yet know why you wanted an iStill, now you do.

Studying the peloton-effect helps us design better stills …

Bubble-Cap Stills Suck at Making Whisky!


There, I said it. I have long considered not writing this post, but the misinformation about this topic affects the craft distilling industry negatively. That needs to be amended. Sure, statements like this will make me some haters, but hopefully that will be compensated by more craft distillers now being able to make better choices. And more importantly: better whiskies.

In this iStill Blog post, I’ll first investigate what a whisky is, and what its flavor profile should be like. Then, I’ll dive into the bubble-cap still design and elaborate on its pro’s and cons. Finally, I’ll explain how the bubble-cap still design prevents the craft distiller from making great whisky.

What’s whisky?

“Whisky is a distilled spirit, made from grain, where one – while drinking it – can identify the grain the whisky is made from”. Don’t you just love the above definition? It so clearly explains everything a whisky needs to be. Made from grain. And with the flavor profile intense enough to allow the drinker to establish the exact grain base. A spicy whisky? Probably rye. A sweet kinda whisky? Corn, so maybe a Bourbon. A mellow whisky? That must be a whisky made from wheat. A complex, full bodied whisky? I am putting my money on malted barley as its grain source.

Grain flavor profiles – and therefore whisky – are quite unique in that they offer front-of-mouth, middle-of-mouth, and back-of-mouth flavors. The floral and fruity flavors can be distinguished in the first second, where heads blend into hearts. The generic grain flavor hits you in the middle of the hearts cut, right after the headsy flavors subsided. The long finish reveals the tails-associated earthy, rooty, and nutty flavors. It is this long finish that is essential to whisky; essential to bringing out not only a long-lasting taste experience, but also the flavor identifiers for the grain bill.

What are the design pro’s and cons of a bubble-cap still?

A bubble-cap design is basically a potstill with two kinds of obstructions in the vapor path. First (from the perspective of the rising vapors), there are the plates with the bubble-caps on them. The gasses need to travel through them. Secondly, the vapors hit a cooler (that is often called a dephlagmator). The plates hamper the free flow of vapors. The cooler liquifies part of the vapors. The liquids fall back on the plates, creating a fixed liquid bath on ‘m. The gasses now have to almost fight their way upwards: through the plate, through the liquids, and through the cooler.

The benefits? Where a potstill can perform only one redistillation cycle, a bubble-cap plated still can perform multiple distillation cycles in one run. No more need for a stripping and finishing run! That’s great news. It helps with time and energy management.

The drawback? Those fixed liquid baths on top of the bubble-cap plates are tails traps. Now, mind you, this isn’t a drawback when producing fruit brandy. Fruit brandy focusses on heads associated flavors. For those fruity flavors to shine, tails smearing (with its heavier flavors) must be prevented. The bubble-cap still was invented for fruit brandy production. Bubble-cap stills offer a great defense against tails smearing. That was the real innovation they brought about, over a century and a half ago. Good for fruit brandy. Bad, really bad for whisky!

Why do bubble-cap stills suck at making whisky?

Bubble-cap stills suck at making whisky because they create two-dimensional spirits, drinks that high-light front-of-mouth and middle-of-mouth flavors. Whisky is (or should be) a three-dimensional drink, that offers a front, a middle, and (most importantly) a back-end.

Over 50% of the flavor is tails associated, is rooty, nutty, and earthy in make-up. It is that third and last dimension that makes or breaks a whisky. Try it. Drink some single malt. Wetten your mouth with a sip, then swallow. Keep your mouth closed. Now start counting. How long do you taste? Where do you taste it? A good fruit brandy is gone in seven seconds. A good whisky lasts and lingers in your throat for 15 to 25 seconds. The difference? Whisky has (or should have) a back-end, fruit brandy shouldn’t.

This is why bubble-cap stills suck at making whisky: they prevent the very flavors, that define any good whisky, from coming over into your spirit. Now that you know it, you can make better purchasing decisions, when starting-up (or reconfiguring) your distillery. Do you want to learn more about stills? The iStill Distilling University teaches you all there is to know about still design. For more information or course registration, please reach out to

Bubble-cap plate …

Bubble-cap still …