Vodka makers have one goal: distill high quality spirits. But doing this also means staying within the legal requirements of what makes vodka, well, vodka. To do this, most use column still versus a pot still. But why is a column still the better choice?
A pot still doesn’t fit the bill mostly because it could never get the job done efficiently. This article explains the differences between column stills and pot stills and why columns are the right tool for vodka making.
Covered in this article:
Vodka, explained
Vodka and Pot Stills
Pot distillation process
Why Pot Stills Aren’t Good for Vodka Distillation
Example of a pot distilled vodka process
Vodka and Column Stills
Continuous distillation process
Example of Vodka by Hybrid Column Still: Industry City Distillery
Conclusion
What is Vodka, Really?
To be vodka, the spirit must be distilled over 190 proof (95% ABV, almost pure ethanol). This process is delicate. A pot still is pretty simple: there’s a pot for boiling liquid, a mechanism to condense vapor, and something to connect these two things together.
In essence, you start with a liquid that’s low in alcohol and slowly increase the alcohol concentration by boiling it off and condensing it back into liquid. This works because alcohol boils at a lower temperature than water and other impurities. Therefore, when boiled, water will mostly stay behind while alcohol is steamed off (steam rises). Distillers can repeat this process if desired (“twice distilled”, etc.).
Vodka and Pot Stills
When it comes to making vodka, “pot distillation” is an inefficient method for one main reason: it takes too many steps to get the alcohol concentration high. This is because of the dynamics of the pot still
How pot distillation happens:
- The “pot” is the large, bulbous base of the still. You’ll recognize it in pictures by its kettle-like appearance. This is where mash, distillers’ beer, and low wine solutions go to be heated.
- The heating/boiling in the pot leads to the steaming and separation of alcohol, which has a lower steaming temperature than the rest of the solution. (Heat sources vary for different still types.)
- As it steams, vapor rises to the swan neck, the curved extension that often becomes more slender as it goes (like a swan). From there, it goes to the lyne arm, the longer extension which connects the pot to the condensing tubes. Different lyne arms are angled according to their desired function. Some angle up, some angle down, some are horizontal.
- The steamed alcohol finds its way to condensing tubes and coils, usually cooled by cold water. Their low temperature causes the steamed alcohol to condense. That condensation is higher concentrated ethanol than we started with at the beginning.
- The higher concentration ethanol is finally channeled through tubes into a collection vessel.
- If a distiller needs to achieve a higher concentration of alcohol, they clean out the still and the whole thing starts over.
The pot still problem with vodka
As I mentioned, distilling vodka requires achieving high concentrations of alcohol. And pot stills take many steps to get there. Put simply, pot distillation produces only incremental spikes in alcohol concentration. So if you start with an 8% alcohol mash (pretty typical) and want it to be 95% alcohol (the 190 proof standard), you’d likely go through TEN steps.
As my Colombian grandmother would say when I’d open a fifth beer–papi, es mucho.
A pot distilled vodka process might look like this:
- 8% alcohol mash goes through a first run (AKA a “stripping run”) to get to ~30% alcohol (it varies between 10% to 40%, just go with it).
- 30% alcohol “high wines” mixture (the base of the distilled product) is distilled again, this time getting to around ~55% alcohol (again, it varies).
- Another repetition takes 55% to ~77%.
- Another repetition takes 77% to ~85%.
- Another repetition takes 85% to ~88%.
- Another repetition takes 88% to ~90%.
- Another repetition takes 90% to ~92%.
- Another repetition takes 92% to ~93%. (Are you getting tired of this yet?)
- Another repetition takes 93% to ~94%.
- Another repetition takes 94% to ~95%. HOORAY, WE MADE IT!
Spot the inefficiency…
The biggest inefficiency here happens from step 7 to step 10, where there’s only a couple of percentage points per distillation. This is why it takes 4 repetitions to go from 90-95% alcohol.
The cause of this slow progression is that later distillations have poor conditions (e.g. boilers full of a 90% alcohol solution). This makes it hard to distill the solution into vodka, including huge losses in alcohol volume from the beginning of a distillation (the “heads”) and the end (the “tails”). That loss can be anywhere between 4-15% of the initial volume lost in the vapors.
The upshot:
Making vodka via pot distillation would be both inefficient and leave you with almost no vodka. Not ideal, to say the least.
This doesn’t mean the pot still is useless. They are great for single or double distilled, low proof distillations. This is the type of distillation that is common in spirits like whiskey and brandy, spirit types that usually sit at about 50-70% alcohol.
Vodka and Column Stills
To be efficient, distillers of double or triple “pot distilled” vodka, like Industry City Distillery in Brooklyn, opt for column stills rather than pot stills. Column stills can also be called “hybrid pot stills”, “craft stills”, or some other name that describes its purpose. You can recognize them visually by spotting a tall, vertical tube with windows at the top of the base. That tube is the column. If you see something like that between the boiler and condenser, you’re looking at some kind of column still.
In contrast to the pot still, a column still can employ a continuous distillation process, meaning that fermented mash is constantly pumped in for heating (the heads) while distilled spirits are continuously coming out the other end (the tails).
Continuous distillation might look something like this:
- Like a pot still, a column still will have a pot or boiler for creating steam. This is pretty much where the pot still-column still similarities stop.
- The fermented mash is poured into the column, at about the halfway point of the column.
- At different levels of the column are plates or trays that slow the fall of the mash. The higher the plate, the further away it is from the heating source and thus the cooler it is.
- As the mash falls through the levels, steam is blasted up from the boiler. This heats the mash and causes it to vaporize, including the alcohol. The alcohol vapors then rise back up through the columns and are condensed by the higher, cooler trays. This causes them to condense and fall back down toward the heat source.
- The mixture is now going through a fast-recurring cycle: vapor-to-liquid and back.
- As the cycle repeats, the alcohol concentration of the mixture rises. This means you are separating the alcohol from the mixture with increasing efficiency.
- Finally, a distiller will remove the alcohol from the still by condensing it and drawing it off.
What makes a column distillation amazing…
Vodka distillers love column distillation because they have internal functions that allow greater concentrations of alcohol to be achieved without multiple iterations–the vapor-to-liquid-to-vapor cycle described above. So the 10-step process I outlined for pot distillation takes ONE step.
It’s obvious why vodka distillers shy away from traditional pot stills in favor of column stills: efficiency. Column stills also have a bonus: an experienced distiller can finely tune one to make anything from (almost) pure alcohol to a rich and flavor-dense mixture being prepped for barreling.
Example of Vodka by Hybrid Column Still: Industry City Distillery
A good example is the aforementioned Industry City Distillery. They wanted to go beyond making “neutral” vodka distilled to 95% alcohol (190 proof). By their own telling they sought to “hunt down the minute flavors” created in their fermenters and make them part of their product. To climb that mountain, they had use both a column still and learn from laboratory distillation techniques.
So they went to The City Foundry to get help designing “the ultimate flavor hunter”–the batch fractional reflux still.
The batch fractional reflux still
Like a column/hybrid still, the batch fractional reflux still has a boiler and a tall column to help separate alcohol from the mixture. But what makes it unique is the ability to reach the absolute highest concentration (95.6% alcohol) in a single distillation. The process was so efficient and remarkable that the team at Industry City Distillery had to develop entirely new methods for creating their vodka.
In the end…
Pot stills are great for their intended purposes. Making vodka just isn’t one of them. The need to distill nearly pure ethanol makes continuous stills a much better option, because it’s far more efficient for that process. Keep this in mind when you’re deciding on what to do for your next batch.