This is a more technical post on a distilling procedure or technique called "stabilization". Underneath, we'll explain what stabilization is, what the advantages are to using stabilization protocols, and what stills offer you this option and which ones don't.
What stabilization is
Stills that have managed columns (see: https://istillblog.com/2021/09/15/liquid-management/) can cool rising gasses into liquids, and return this as reflux down the column for further processing. "Stabilization" is the situation where all the rising gasses are cooled back down to liquid phase and returned down the column. No product comes out of the still. The still - and column - are in a stable state, where the boiler creates certain amounts of gasses and the column cooler or dephlagmator cools these gasses down into reflux that is returned (all of it) down the column. The still should be able to stabilize for prolonged periods of time, like up to an hour.
The benefits of stabilization are basically twofold:
Since less distillation cycles equals more flavor (see: https://istillblog.com/2021/09/02/less-is-more/), the second point is important. A still that allows you to stabilize, supports a higher proof output. A distillation run that produces hearts at a higher output ABV (alcohol by volume) in one single run results in less distillation cycles needed. Less distillation cycles equals less work, better efficiency, faster throughput, and more remaining flavor.
Going from, for example, a double distillation approach to a single distillation approach, using the above stabilization technique, results in 33% more flavor. The total workload and efficiency advantages are in the neighborhood of 50%.
Another advantage of the stabilization technique is heads compaction. If you start your distillation run with a stabilization period, this gives the column time to collect and concentrate all of the headsy molecules into a small faction. In a normal run, without stabilization, heads come over in the first part of the run, but they are basically a mixture of good ethanol with some heads. By putting the still in stabilization mode, more and more headsy molecules are presented to the column. The column can now concentrate all of these headsy components near the top of the still, resulting in much smaller heads losses and a better separation between heads and hearts.
On a typical 2000 liter gin run, we end up with one to two liters of heads, using stabilization. Compare that to a distillation run on a still that cannot stabilize and looses 20 to 25 liters easily. The stabilization protocol produces 40+ additional bottles per run!
On a typical 1.5 distilling 2000 liter whisky finishing run, the stabilization approach results in heads losses of less than one (1!) liter. Compared to that, a standard potstill looses of 20 to 30 liters to its heads cut. That's over 10% of a barrel fill!
Stills that support stabilization
Stills with actively managed columns potentially allow you to stabilize. Stills without active column management do not. So, just to keep things easy, potstills cannot stabilize. Their columns are passive (and therefore called "risers" instead of columns).
Stills with the 1870's cooling management technology (AKA fruit brandy stills with dephlagmators and plates) theoretically can go into stabilization mode. Adding more cooling water will result in more and more gasses becoming reflux. There is a caveat though. Cooling management columns do not have air pressure equalization. Stabilization potentially results in pressure build-up in the still. The bigger the still, the greater the chance is that the still will become, well, basically a very dangerous piece of equipment. We therefore advise not to use stabilization procedures in these types of stills (provided by Mueller, Holstein, Kothe, DYE, StillDragon, and Vendome). The benefit isn't worth the risk.
The only type of still that can successfully and without any risk perform stabilization procedures are stills that have liquid management columns. Liquid management columns equalize for air pressure, so pressure cannot build up during a run or during stabilization. You probably guessed it by now: iStills are the only stills with liquid management columns, iStills are the only stills that give you the amazing benefits of stabilization. Liquid management is iStill's proprietary technology.
A real-world example
See the picture underneath and allow us to explain what you are looking at. In the first column you see the numbers at which the master distiller wants the iStill to cut. As you can see, the iStill will heat-up until the temperature near the top of the still is 45 degrees Celsius.
The last column in the picture, the one to the right, tells you that heating up takes place at 100% power. At 45 degrees Celsius, the power switches down to 80% and fores (the first bit of heads, used to clean out the column) are taken.
At 82 degrees Celsius, it moves over to the heads faction. You can see, in the second column on the picture underneath, that it will first stabilize for 30 minutes, and then take heads (1 time) until the column is 79.5 degrees Celsius. When this heads separation step is done, the iStill stabilizes again for 20 minutes before taking hearts.
The procedure shown underneath and explained above, allows the master distiller to make amazing tasting rum in one go. It brings a 10% rum wash to the perfect barrel aging strength of 62% in one distillation run, saving him a second run, and resulting in a more flavorful product. As iStill customer John puts it:
"So ... I did my first 1.0 rum run today. I have ended up with a great tasting rum at 62% ABV in one go and have probably halved my rum production time going forward."
In the run underneath, the customer stabilizes for heads (30 minutes) and hearts (20 minutes) ...
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