School is in session: Distilling 101

"Merica Whiskey Alright kids, school is in session.  This is going to be a rough and tumble crash course on distilling.  I’m not a chemist, I’m not a professional, hell, I’m surprised my chef lets me touch the mop bucket to swab the deck. That being said, I know my way around a bottle of booze and can shed a little bit of light as to how that booze got into that magical bottle.

It all starts with something that ferments, whether that something is Malted Barley, Fruit, Potato Starch, Sugar or Molasses, really anything that is going to ferment. At this point, these distillers are making brewer’s beer or their “wash”. The Fermentable sugars in the wash are consumed by the yeast, which do their duty to piss alcohol and fart CO2.  Seriously, that is their duty.  At the end of fermentation, the wash is going to be 4-7% alcohol and 96-93% water. Again, depending on the producer, this wash is going to run the range of flavor profiles; it could be relatively flavorless or completely full of flavor. It all depends on the desired end-result. I’ve tasted washes that taste like oatmeal, and I’ve tasted washes that are incredibly deliciously complex, tart and sour. True Story: I love Leopold Bro’s Maryland Rye, but they could have bottled the mash and I would have almost been just as happy. It was that good.

Roundhouse

Roundhouse stills

The distiller then loads the wash into a still.  This still could be shaped like a little onion (pot still or alembic still), a couple of Jerry-rigged beer kegs to make moonshine, a gleaming 5-story tall column still, or a combination of all three.  Essentially, the still is going to separate the water from the alcohol, leaving the water in the still, with the alcohol evaporating into a tube.  It then condenses, and the condensed alcohol is collected.

Different shapes of stills bring different things to the table. By applying heat to the wash in the still, ‘stuff’ is going to evaporate off. Because alcohol and water have different molecular weights, they are going to evaporate at different temperatures.  Distillers get even geekier realizing that the earlier stuff that is going to evaporate, known as “the heads,” are really volatile, gross, and harsh. Usually these are discarded or poured out for the distiller’s homies. After the Pachamama has been appeased, the distiller returns to the still to find the center cut of the alcohol is coming out.

Methanol and Acetone are some of the primary chemicals that dominate the first cut, the heads. Old Wives’ tales would have you believe that drinking these will make you go blind or kill you. While a spirit that contains a lot of heads or a lot of tails won’t kill you, it may give you a slightly more bruising hangover.

The middle cut is often referred to as “the heart”. This is the stuff that the distiller wants to keep. Following the heart is “the tails”, the heaviest oils and volatile compounds that come off at the end of the distillation.  It is subjective as to when a distiller chooses to make the cut of the heart, or when to start collecting and when to stop; it’s subjective and this is what makes distillation such an art. The tails are either redistilled following the same process as before, or they could be discarded.  A distiller looking to make a flavorful distillate is going to want to keep some of those tails in the spirit because they are going to add character and aromatics over time. This is a good thing for whiskies and rums, not so much if you are looking to make vodka or a base spirit for gin or liqueurs.

Rob Masters

Rob Masters' Roxy the Gin Still with special column

Now, if the distiller is working with a potstill, the first distillation is going to produce alcohol in the 15-25% range. They then take this distillate and redistill to bring the alcohol content up in the 40-55% range. Each distillation is going to remove more congeners (by-product of fermentation) and volatile compounds. If the distiller has a column still or a Coffey still (or a massive ‘pot’ still like those in Ireland) it acts like a closed-loop, the alcohol is constantly being redistilled within the still (blowing your mind right now, right?!). This closed loop system is capable of separating almost all of the alcohol from the water.  Distillers looking to create a really clean spirit utilize a column still. At the end of the day, the product from a column still is going to be NGS (Neutral Grain Spirit). NGS must be high proof; think Everclear. In order to be called Vodka, you’ve got to be playing around in this high-proof territory.

Now, just to make things complicated, distillers also can choose to purchase already-distilled alcohol. It would take forever to constantly be refilling and redistilling in a pot still to achieve something close to 95-100% alcohol, so some distillers choose to purchase NGS. This provides them with a blank canvas into which they can then flavor. Especially when making Gin, it is a stylistic choice to have a really clean NGS so your botanical choices are going to be the focus of the show. After flavoring the NGS with what have you, they then use the still to filter out any of remaining organic products.

Just to re-iterate: distillation does not produce any alcohol, it’s the brewing and the fermentation that happens before hand that produces actual alcohol.  Distilling is simply a means of separating the alcohol from the water.

And voila.  That’s the skinny on distilling. As always, the Colorado Distillers Guild is also a great resource.

Laboratory display of distillation: 1: A heating device 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed control 13: Stirrer/heat plate 14: Heating (Oil/sand) bath 15: Stirring means e.g.(shown), anti-bumping granules or mechanical stirrer 16: Cooling bath

About Kevin Burke


Kevin is an occasional barman and fulltime practitioner of the Janitorial Arts at Colt & Gray.

  • http://www.bigmargaritacrawl.com Mike

    Thanks for a very informative post – the distiller interviews will make much more sense now!

  • Ryan

    Awesome. I want to put a micro still on my counter.

    • Kevin Burke

      One can find ‘decorative’ copper alembic stills that may or may not function if used properly. Home brewing is very different than home distillation. As easy as we broke it down, there are some chemicals and by-products of distillation that can seriously harm the imbiber and distiller. Just a few weeks ago, a moonshine distillery in Linconshire UK exploded killing 5 individuals.

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    Looking for new ways to have good water.