Single vs Double vs Reflux Distillation – What and Why

Single distillation, double distillation, 10x distilled what does it mean?  This refers to the number of times that liquid is vaporized and then condensed back to a liquid.

Why do Multiple Distillations?

There are several reasons you may want to run multiple distillations.

• Reduce the volume of wash (stripping run)
• Increase the proof
• Improve the flavor and quality
• Create a neutral spirit

Reducing Volume – Stripping Runs

One of the most common reasons for multiple distillations is for stripping runs.  It is easy to produce a large volume of wash, but you may not have a still large enough to run it all.

In this case you could run several slow distillations making cuts on each to get through the wash, but a faster method is to run several stripping runs collecting the alcohol as quickly as possible into a large container.  Then combine those runs into 1 spirit run that you run slower and make your cuts on.

The final lesson the the beginner series discusses stripping runs in more detail.

Increase the Proof

With each distillation the proof of the alcohol will increase.  If you start with a 10% abv wash for your stripping run, you could easily start your next run at 40% abv and finish with a much higher proof hearts cut than the initial run would have been.

This doesn’t mean that you can collect an 80% abv distillate and then dump that back into your still though.

40% abv is the highest proof you should put into the pot to start a run.

Anything higher than that could be a safety concern.  A way to get higher proof without charging your pot above 40% is to use a column still with plates, more on that later in the article.

Improving the flavor and quality

Each time you distill a liquid you are leaving some of the compounds in the pot of the still.  This means that some of the flavors are also left behind.

Double distillation is a very common way to run whiskey or bourbon.  This still keeps enough of the flavor that you worked hard to build in when creating your mash bill but cleans it up a little bit.

Making Vodka or Neutral Spirit

If you want to make a flavorless neutral spirit like vodka or a base for gin, you will want to strip out as much flavor as you can, this is commonly done using column stills.

How to do multiple distillations

There are several ways to do multiple distillations, either multiple passes using the same equipment or you could do a single pass that performs several distillations at once.

Let’s look at some of the ways this is done.

1 and a Half, 1-1/2 or 1.5 Times Distilled

This one may seem the most confusing, but it really isn’t.

A 1-1/2 distillation is when you split your wash and perform a stripping run on half of it.  Then you combine the low wines from the stripping run to the other half of your wash and run it a second time.  This results in half of the wash being distilled 2x and the other half only once giving the name 1.5 times distilled.

You will retain lots of flavor with this method.

Double Distilled (2 Runs)

Like the last method this involves 1 or more stripping runs and then combining them for a spirit run resulting in all of the wash passing through the still 2x.  This is most commonly done using a pot still and will still retain a lot of flavors from the mash.

Thumpers and Retorts (Double Distilled or more)

Another method of multiple distillations is to use a thumper or retort.  This is a pot connected in the vapor path after the still pot and head.  The thumper is partially filled with either more wash, low wines or it could be filled with juice or something else to add additional flavor to the distillate.

The wash is vaporized in the pot and flows into the thumper where it is released below the level of the liquid causing it to condense.  It is vaporized again before flowing into the condenser to be collected.  That creates a second distillation.

Multiple thumpers or retorts can be connected to create as many distillations as you want but there are limitations.  The thumper is only heated by the vapor flowing in from the still so you will eventually run out of energy. 

Jamaican rum is often run through a triple retort system where each stage is charged with a higher proof rum from previous runs.  This helps with flavor consistency in their product.

Warning: Thumpers and retorts create a closed system between the pot and thumper so if you don’t disconnect something to vent after a run the cooling could cause your still to collapse.

Column Stills

A column still uses plates to achieve multiple distillations during the same run.  A plate fits between 2 sections of the column and allows a layer of liquid to form on the plate that can then vaporize causing another distillation.  Column stills require reflux to maintain the liquid layer on the plate.  This is done by adding a small condenser called a dephlegmator at the top of the column.  The dephlegmator forces some of the vapor to condense and fall back down the column while the purer ethanol passes through.

The addition of more plates creates more distillations, increasing proof and purity as the vapor travels up towards the condenser.  The use of a column and plates will compress the heads and tails during the run making a quicker transition between hearts and those parts of the run you don’t want to keep.  This is the method you should use for Vodka

Continuous Stills

A continuous still works similarly to a column still, but instead of a pot that needs to filled and run in batches the wash is continuously fed into the column.  In order to separate the parts of the run heads, hearts, and tails are taken off from connections to different levels of the column.  These are typically used in commercial distilleries and aren’t common for home distillers.

Wrap up

Hopefully now you understand the benefits and process for different numbers of distillations.  Playing with different processes and methods is one of the great parts of being a home distiller.  Some recipes are great with a single pass and others need to be run through 3 plates on a column to really shine.

Let me know in the comments if you have any questions or what your favorite recipe is and how you like to run it.