What we post here is an account of iStill's CEO, Odin, helping out a distiller that has difficulty choosing the right still for his distillery. The distiller got a one-day training on a Holstein and now mistakes a short run-time for speedy and efficient production. There is also a mismatch between the product he wants to make (whiskey) and the product the Holstein is designed to make, which translates to underwhelming spirit quality.
There are two reasons to post this on the iStill Blog. First, it can help create awareness that there are many poorly designed stills out there. And if you end up buying one, you might find yourself in a bad situation, where you cannot produce the quality or product you aimed for. Let this iStill Blog post serve as a warning. Secondly, this post shows that still design is a science, based on facts, and not something artsy-fartsy, romantic, close to magical, based on opinions.
This post does not intend to harm another manufacturer of distilling equipment. Even though, after reading what we have to share, it may feel like it isn't exactly a positive endorsement for them either. We considered what was more important: informing you, so you will be better prepared when it comes to still selection and purchase, or keeping our mouths shut and supporting the BS out there, even though it might hurt fellow craft distillers as yourselves. We decided to do the first. If for no other reason, simply because of all the positive feedback you gave us on the first post on poor still design from just two weeks ago. And it isn't the first Holstein we encounter with a column too big for its boiler.
The distiller's still design misconception
The distiller had a one-day training on a 600 liter Holstein with a huge column and overcapacity steam boiler. This allowed the training facility to do a run in around 2 1/2 hours, resulting in 3 runs during a (training) day. Given the advanced technology iStill has on offer, he reached out to us and asked us if the iStills also do 2 1/2 hour runs. At first, he didn't understand why iStills have run times of around 8 hours, so Odin explained it to him.
"From a still designer's perspective, a still that performs a run, from start to finish, in 2 1/2 to 3 hours, is a sub-optimal design. If the heat source and the column are so big, that they can process a boiler-fill in such a limited amount of time, to me that signals that the boiler is basically way too small. This may be beneficial for training, but not for actual distilling.
I design the iStills with a normal workday in mind. And a normal workday is 8 hours. Why I choose that approach? Well, imagine that every run starts with filling the boiler, then heat-up, then the actual run, then draining the boiler remains, and finally: cleaning. Filling, heat-up, draining, and cleaning are basically down-time. Since it is down-time, it is basically an inefficiency that you want to minimize. So, when designing a still, I want to limit the time spent with these downtime processes. And by far the best way to achieve that, is by designing boiler size, heat-source, and column in such a way that the total run time, of a single run, is close to 8 hours. The distiller now only has to fill, heat-up, discharge, and clean his still once. Filling and heating-up before the run. Discharging and cleaning, only once a day, at the end of the run.
A still with too small a boiler, that has a run time of 2 1/2 to three hours, needs multiple fill, heat-up, discharge and cleaning cycles. Multiple runs translate to a longer total down-time. And beware: you now also need to attach and clean the pump and hoses twice or three times during your 8 hour workday, so inefficiencies accumulate."
The distiller intervened and said that he loved the speed of the 600 liter Holstein. "That way I can do 3 runs a day and process 1800 liters!" Upon understanding that the iStill 500 would run for around 8 hours, he said: "So that unit is very slow, then, isn't it?"
"The iStill 500 is not slow; it is a machine that is optimized for an 8 hour workday, with the goal to limit down-time. If you want to process 1800 liters per day, like you could do in the small boiler designed Holstein, you need to compare it to the iStill 2000. A unit that can not just process 1800 liters, but 2000 liters in 8 hours - a first easy gain of 10% over running the Holstein three times a day.
Not only does the iStill 2000 give you 10% more capacity, it does so while being more affordable to purchase and less costly to run. The iStill 2000 costs EUR 70.000,- with all options included, the heating system being an integral part of the system. The Holstein costs EUR 200.000,- and that's without investing in the heat source (a 50k steam boiler) and piping (another 50k). Purchase-wise the iStill 2000 costs only a fourth of the installation price of the Holstein. Given the 90% efficiency of the iStill, and comparing it to the 30 to 40% efficiency of a Holstein, expect your run costs per liter of spirits produced to double or triple, when opting for an uninsulated, copper, traditional, 1870's still design from Germany."
Spirit quality misconception
By now, the distiller thoroughly got wat Odin was explaining, and he moved on to the next topic: even though the distiller thoroughly loved the training experience on the Holstein, he felt the whiskey / New Make Spirit they made was not very impressive. He wanted to make sure that iStill could help him at making better spirits.
"The Holstein uses bubble capped plate technology. This is a Southern German (some say Elzas) innovation to help make better fruit brandy. Bubble caps create a structural (fixed) liquid bath on the redistillation plates, that work amazingly well as a tails trap. No tails come over, which tremendously helps fruit brandy production, because fruit brandy is a forward cut, headsy, fruity product that can easily be overwhelmed by non-intended tails smearing.
Whiskey is different, the opposite almost, because whiskey is a 3-dimensional product, heavily dependent on tails smearing, with a long resulting throaty, nutty, root-like, earthy finish. The reason why you were not impressed with the New Make Spirit produced on the Holstein, is because it basically is a machine intended to make fruit brandy, not whiskey. As a result the New Make Spirit you made and tasted lacked in back-end flavor. No worries with the iStill. We do not use bubble cap plates that prevent gentle early tails smearing. With an iStill you, not the (antiquated) technology, decide on the amount of heads and tails smearing, and the associated fruity and nutty, earthy flavors you get over in your drink.
Finally, there are two more things to consider. Remember the short vs. long run times? And the steam boiler that indirectly fires the Holstein? Indirect heating, like in the Holstein, prevents the Maillard Reaction to take place. All iStills have direct, instead of indirect, heating, because the associated Maillard Reaction gives our customers up to 25% more flavor. And longer runs add to esterification (the longer runs help create more esters AKA flavor molecules). The short run-time of the sub-standard design you trained on prevented additional esterification to take place. There you have it: sub-standard design leads to the meager taste you experienced, via the prevention of tails smearing, a lack of Maillard Reaction, and low overall esterification.
A lengthy answer, but I hope you like the effort of me informing you about potential issues so you can better decide on the most adequate distilling solution for your future craft distillery.
The iStill 2000: optimized for an effective workday at the distillery ...