How distilling works - and where Stilligent fits in

An introduction to distilling: what happens inside a still, how a run unfolds from a cold boiler to the final cut, and where Stilligent fits in. Written for newcomers, and useful for anyone.

New to the vocabulary? Terms like wash, reflux and hearts are underlined where they first matter - tap one for a quick definition, or browse them all in the glossary.

Distilling spirits is regulated, and in many countries illegal without a licence. This page explains how the process works; it is not encouragement to break the law. Check the rules where you live before you build or run a still, and read the important notice on safety.

01 · The basics

Separating a mixture by heating it

Distillation works because different substances boil at different temperatures. Heat a mixture gently and whatever boils most easily leaves first, as vapour. Cool that vapour and it becomes liquid again - now separated from the rest.

Spirits begin with fermentation: yeast turns sugar into alcohol, leaving a liquid called the wash. It is mostly water, typically 8–15% ABV, plus traces of many other compounds, known as congeners. Some give a spirit its flavour, some taste harsh, and a few are harmful.

Ethanol boils at about 78 °C, water at 100 °C. Heat the wash in a boiler and the vapour that rises through the column is far richer in alcohol than the liquid it came from. A condenser turns it back into a stronger liquid than the one you started with.

02 · Types of still

Pot stills and reflux stills

There are two broad families of still. Stilligent works with both.

The pot still

A boiler, a short neck and a condenser. Separation in one pass is modest, so plenty of flavour comes through - the character of whisky, rum and brandy. Pot stills are usually run twice: a fast stripping run that concentrates the alcohol into low wines, then a careful spirit run.

The reflux still

Adds a tall column. Some vapour condenses on the way up and runs back down - this is reflux - where it meets rising vapour and is re-evaporated. In effect the liquid is distilled many times in a single run, producing a cleaner, more neutral spirit such as vodka or a gin base.

	Pot still	Reflux still
Separation	Modest - about one distillation per pass	Strong - many evaporate-and-condense cycles
Typical strength	Around 60–80% ABV	Can approach 95% ABV
Character	Rich and flavourful	Clean and neutral
Runs	Often two (strip, then spirit)	Often one

Pot still, reflux still or column: which is right for you? →

03 · Reading the still

Why temperature tells you what's coming out

A sensor at the column head measures the vapour just before it reaches the condenser - the vapour that is about to become your spirit. Its temperature reveals what that vapour is made of. Fitted in a thermowell, it reads the vapour rather than the metal around it. The boiler temperature is a slower companion that shows how much alcohol is left.

Compound	Boils at	What it means for the run
Acetone	≈ 56 °C	A solvent. Foreshots.
Methanol	≈ 65 °C	Toxic. Concentrates early in the run, though it does not separate perfectly.
Ethyl acetate	≈ 77 °C	Sweet, solvent-like. Heads.
Ethanol	≈ 78 °C	The drinking alcohol - the point of the whole exercise.
Water	100 °C	Mostly stays behind, but comes over increasingly as the run goes on.

Boiling points of the pure compounds at sea-level pressure.

Mixtures behave differently

In a real wash these compounds are dissolved together. A wash at about 10% ABV doesn't boil until roughly 92 °C, and drifts towards 100 °C as its alcohol is used up. A little water always rides along with the vapour, which is why ordinary distillation can't take alcohol much beyond about 96%.

Air pressure moves the numbers

Boiling points fall as air pressure falls - and air pressure falls with altitude and shifts with the weather. The effect on cuts is significant: in Mexico City, about 2,240 m above sea level, air pressure is around 770 hPa and ethanol boils at about 72 °C rather than 78 °C. Stilligent adjusts every threshold to your local pressure, taken from an optional sensor, an online weather service, a phone's own sensors, or a reading entered by hand. See distilling at altitude.

Why a temperature chart can't tell you when to cut →

04 · The cuts

The art of the cut

Everything that drips from the still is divided into four cuts - foreshots, heads, hearts and tails. Where you draw the lines between them decides whether a spirit turns out harsh, bland or beautiful - the most important judgement in distilling, and the hardest to get right every time.

Foreshots

The first few drops

Volatile solvents, including methanol, with a sharp, nail-polish smell.

Discard

Heads

Bright, but harsh

Fruity and solvent-like at once. The move into hearts is where much of a spirit's character is won or lost.

Set aside as feints

Hearts

The reason for the run

Clean, smooth and sweet - the spirit you are making. Collected slowly, at gentle heat, for the cleanest separation.

Keep

Tails

Fading strength

Weaker and oily, heavy with fusel oils and a wet-cardboard note.

Save for a later run

Why a thermometer isn't enough

A thermometer gives you a number. A good cut depends on what that number means - for this recipe, on this still, under today's conditions. That is the knowledge an experienced distiller carries in their head, and the knowledge Stilligent is built to hold.

Same reading, different day - different cut.

Every recipe has its own cut points

A fruit brandy might keep more of the late heads for aroma; a neutral spirit is cut tight on both sides. Stilligent keeps a recipe for each spirit you make, each with its own cut points and, if you like, its own heat settings. It comes with starter recipes for whisky, brandy, rum, neutral and flavoured spirits; copy one as a starting point, or import and export your own.
Adjusted for today's conditions

Cut points are kept as they would be at sea level for a standard wash. On the day, Stilligent adjusts them for the atmospheric pressure, which shifts every boiling point with altitude and weather, and for the strength of the wash in the boiler. Right last month; still right today.
It learns your judgement

One tap makes a cut by nose and palate, with a quick confirmation so it is never made by accident; if a suggested cut comes too early, Not yet keeps collecting. Every cut is recorded, and you can rate the run, add tasting notes and mark the jars you blended. After each run the recipe moves gently towards your choices - and the learning can be switched off, or any change undone.
It shapes the cut, not just calls it

It eases the heat through the hearts for cleaner separation and speeds up through the tails - and it never gets tired or distracted, four hours into a run.

You can override any cut, at any time. Cut detection is a guide to separation and quality; it does not confirm what is in the collected spirit.

The full guide: making the cuts, jar by jar →

05 · The process

A run, step by step

A run takes several hours. Here is what happens inside the still - and, alongside each step, what Stilligent does. Every automatic decision can be overridden.

Setting up

The boiler is filled with wash (or low wines for a spirit run) and the run's details are decided.

Stilligent
You choose the recipe and enter the volume, starting ABV and run type; Stilligent then runs the whole distillation to that recipe. Everything else - bottle size, alarms, heat - has sensible defaults in Settings.
Warm-up

Heat goes in and, for a while, nothing comes out: the energy is spent warming a large volume of liquid. Most distillers use high power here to save time.

Stilligent
Heats at full power, then eases back automatically as the column head reaches temperature. Power is set in kilowatts, so the same setting gives the same heat on any day. The same controlled ramp is used after any pause.
The column comes up to temperature

Early vapour condenses on the cold column walls, warming the metal from the bottom up until hot vapour reaches the head. A reflux column is usually left to settle before anything is collected.

Stilligent
Checks that the boiler and column respond to heat as expected - an early sign that sensors and still are behaving plausibly.
Collection and cuts

Liquid begins to drip from the condenser, and the run moves through foreshots, heads, hearts and tails as the head temperature changes.

Stilligent
Announces each phase as its threshold is crossed, collects the hearts at reduced power, and tracks drip rate, volume per cut and an estimated ABV. An alert sounds before a receiving bottle overflows. You can make any cut yourself with one tap.
Wind-down

The alcohol is nearly exhausted, the boiler heads towards 100 °C and what drips out is weak and oily. The heater is switched off and the still allowed to cool.

Stilligent
Raises power to bring the tails through quickly, then switches the heater off at the finish threshold - or, if you want to keep collecting, asks first and hands the stop decision to you.

Stripping run and spirit run: why distil twice? →

06 · Where Stilligent fits in

A controller that thinks like a distiller

Distilling well asks for hours of close attention - reading temperatures, adjusting the heat, judging each cut, changing receivers. Stilligent takes on that work and keeps you informed on a phone, tablet or laptop, while you remain in charge of the still.

Simplifies

Calls every phase

Reads the column head and boiler temperatures continuously and announces each transition as it happens.

Controls

Manages heater power

Full power to warm up, gentle for the hearts, raised again for the tails - set in kilowatts and held steady as the mains voltage rises and falls, across up to four elements.

Optimises

Learns your still

Corrects for wash strength and air pressure, and learns how your still and recipe behave over successive runs, for more consistent results.

Monitors

Watches for faults

Checks sensors and process behaviour continuously - above all the column-head sensor - and stops heating at the first sign of trouble.

Specifications

Stills and runs: Pot stills and reflux columns; stripping and spirit runs
Recipes: One per spirit, with its own cut points and optional heat settings; starter recipes for whisky, brandy, rum, neutral (pot or reflux) and flavoured spirits; copy, import and export
Measurement: Column-head and boiler temperature; atmospheric pressure from a sensor, online weather data, a phone or manual entry
Heat: Up to four heating elements, each smoothly controlled by a heating power regulator or switched by its Smart Watchdog; power set in kilowatts and compensated for mains voltage
Control: Cooling fans and condenser cooling
Independent cut-off: A Smart Watchdog for each element: separate hardware that measures its power and can switch it off without the controller
Protection: Three-level watchdog; start-up checks; column-head sensor monitoring; a failed element is switched off while the run continues on the others; restarts with the heater off and the run paused
Alerts and alarms: Chime for alerts; non-critical and critical alarms; phone notifications; relay to call for help via a siren or alarm panel
Interface: Any modern browser - phone, tablet or PC; Stilligent API for integration
Records: Live charts, event log, energy per run, run ratings and tasting notes, CSV export
Controllers: Teracom TCW280 and TCW241; simulation mode at 1×–50×

Try it in your browser

The demo is the real interface, connected to a live controller driving a simulated still instead of hardware. Time runs at anything from 1× to 50×, so a full spirit run can take just a few minutes. Change thresholds, drop the power, pause and resume - nothing you do there can break anything.

Open the demo

Where things stand

Stilligent has been in development for several years and is test-run weekly on our own stills. It is not yet available to the public, and features may change before release. The plan is a turnkey unit: purpose-built control hardware with connectors for sensors, fans and heating element, with Stilligent preloaded.

07 · Safety

An extra layer of protection

Stilligent is designed so that no single failure leaves the element heating; it alerts you when you are needed, and raises the alarm when something goes wrong. It is a monitoring and control aid, not a safety device: it complements, but never replaces, independent safeguards and an operator present for the whole run.

Safety in detail →

Distilling safely: the hazards and good practice →

Thinking about Stilligent for your still?

See it run in the demo, and ask anything on the forum, where we answer alongside other distillers. To talk about using Stilligent on your own setup, contact us.

Open the demo Ask on the forum