Yep, we don’t own a pot still. Sure, we have a still and it has a “pot” boiler, but that’s where the similarities begin to decline. When we started Industry City Distillery, the goal from day one was to create vodka, so we commissioned equipment to do just that. 

95.6% alcohol coming off  our main condenser

Vodka has a few legal requirements that make it “vodka”, but the most important one is the proof that it’s distilled to, and you just can’t do it efficiently with a pot still. Here we’ll look at how pot stills work, why they’re a bad match for vodka, and what other options are out there.

Vodka by definition has to be distilled over 190 proof (95% alcohol by volume), and this can be a little tricky. Pot stills are fairly simple contraptions that are basically exactly what they sound like: a pot to boil up liquid, something to condense the vapor, and a connecting piece between the two. The idea is that if you start with a liquid that contains a low percentage of alcohol you can incrementally concentrate it by boiling off that alcohol and condensing it back into liquid. Because alcohol boils at a lower temperature than water, most of the water is left behind. You’ve probably seen bottles of liquor that are distilled once, twice or even more, and this literally means the number of times that a boiler has been loaded, a separation has been made, and vapor condensed and collected. 

The key to the “pot distilled" vodka problem is in the incremental increases in each re-distillation. Say you start with a fairly typical mash of with 8% alcohol and want to turn that into vodka at 190 proof (95% alcohol). Your first pot still run (also called a stripping run) is going to result in a distillate at about 30% alcohol (it’s actually a range from 10% to 40% over the run, but we’ll work in averages). This is called “high wines” and represents the base of the distilled product. You’d now take those 30% alcohol high wines, and distill again to collect at around 55% alcohol (a range from 45% to 75%). You’d then repeat the process over and over again to slowly step up the alcohol concentration (purity is another thing entirely…) until you reach 95%. 

How many times? Well, the full 8% to 95% concentration process in a pot still would look a bit like this:

8% (starting mash) → 30% (high wines) → 55% → 77% → 85% → 88% → 90% → 92% → 93% → 94% and finally → 95% ABV vodka. That’s a lot of steps!

You’ll also notice that from 92% to 95%, the increases are pretty slow going, with only a few average percentage increases per distillation. These later distillations also have some pretty unlikely conditions like boilers full of 90% alcohol! What also isn’t shown here is the amount of alcohol that is removed at the beginning of the distillation step (the “heads”) or the amount that has to stay in the boiler at the end (the “tails”). It can be substantial, with 4-15% of every distillation step being thrown away. This means that making vodka with a real pot still would leave you with almost no vodka at all… 

Where pot stills can shine though is in single or double distilled, low proof distillations.

Pot stills being installed at nearby Kings County Distillery image by Michael Appleton for The New York Times

Stills and techniques like this are perfect for spirits like whiskeys or brandies, since you really only need to get to 50-70% alcohol for the final product. What we realized is that while it’s not technically impossible to pot distill vodka, it’s really not all that practical. 

So how do the  double or triple “pot distilled” vodka’s do it? Simple - they don’t use pot stills. Instead they use what’s called a column still, though in some cases it may be called a “hybrid pot still”, a “craft still” or something similar. You’ve probably seen them, a tall vertical tube with little windows in it right on top of the “pot still” base.

This beautiful still at Purity Vodka in Sweden is gorgeous, but it’s definitely not a pot still! image by www.alcademics.com

Basically, if there is something like this between the boiler and condenser, you’re looking at a column still of some variety. Column stills are great! Rather than having to do 10 distillations to get to 95%, they have a number of internal workings that allow far greater concentrations of alcohol to be reached with a single distillation. What’s even better is that in the hand of a skilled distiller, they can be tuned to create anything from a very pure alcohol to a very rich and flavorful melange destined for a charred whiskey barrel. 

For Industry City Distillery, we took it another step beyond the column still. We didn’t just want to make vodka that was “neutral” and distilled at 190 proof, we wanted to hunt down the minute flavors that we created in our fermenters and make them part of our spirit. To do that we had to look beyond the craft column still and take a lesson (or 12…) from laboratory distillation techniques. With the services of the lab and the shop at The City Foundry, the Distillery was able to design, craft and utilize the ultimate flavor hunter; the batch fractional reflux still. Like a hybrid still, it has a boiler and a tall column to aid in separation, but it achieves separation an order of magnitude above what a typical column would be capable of. Reaching a concentration of 95.6% alcohol (the absolute maximum possible concentration of alcohol in atmosphere!) with only a single distillation, the fractional reflux still was able to separate out all of the components in a distillation to such a high degree that we had to develop new ways of creating our vodka.

Packing material in the batch fractional reflux column

Check back later as we go into how the batch fractional reflux still allows us to “build” our vodka using a technique we call “blending”, completely eliminates the need (or want!) for charcoal filtering, and how the the still design itself allows us to be energy efficient and reduce waste.