Glossary

(Substance) Absolutes are concentrated solvent-based aromatic products used in perfumery and aromatherapy. It’s an extraction technique where botanicals and other aromatic substances are steeped in a solvent (usually hexane or toluene), which draws out aroma molecules. The resulting waxy or resinous substance is then steeped in ethanol and filtered, which separates out the undesirable solids from the aromatics. Finally the ethanol is removed (or ‘recovered’) using vacuum distillation leaving the thick and concentrated absolute.

(Measure) Alcohol By Volume. ABV is a standard measure for the amount of alcohol in an alcoholic drink, expressed as a percentage. It is the number of millilitres of ethanol present in 100ml of the beverage, at 20°C. For example—wine has an ABV of around 13%, while most gins come in around the 40% mark.

A tip when distilling spirits—fluctuating ABV readings can be due to the changing temperature of your distillate. ABV readings will be higher at hotter temperatures, so take all readings at room temp.

(Organic compound) Alcohol is the family name of a group of organic chemical compounds, but here it’s most commonly used to refer to the product we aim to distil, which is ethanol. Different types of alcohol have different boiling points, which enables us to separate them from each other and from other organic compounds:

*Acetone 56.5ºC (134ºF)

Methanol (wood alcohol) 64ºC (147ºF)

Ethyl acetate 77.1°C (171ºF)

Ethanol 78ºC (172ºF)

2-Propanol (rubbing alcohol) 82ºC (180ºF)

1-Propanol 97ºC (207ºF)

Water 100ºC (212ºF)

Butanol 116ºC (241ºF)

Amyl alcohol 137.8ºC (280ºF)

Furfural 161ºC (322ºF)

*please note, acetone is actually a ketone not an alcohol, but it is included in this information as it’s one of the first compounds separated out in the heads of an alcohol distillation.

(Industrial product) Ethyl alcohol (ethanol) made unfit for drinking, but still suitable for industrial or domestic purposes.

Many different additives can be used to achieve this, but the main additive is often methanol, hence the term ‘methylated spirits’. Denatured alcohol is often coloured to distinguish it from drinkable spirits, and for many of these solutions, it is intentionally difficult to separate the components. Such products are freed from internal revenue tax in many countries.

(Product of distillation) Ethyl alcohol, often simply called just ‘alcohol’ this is the type of alcohol used in alcoholic beverages, as it’s safe to drink. Most uses of the word ‘alcohol’ on this site refer to ethanol, as it’s the type we use to make beverages, tinctures and as bases for perfumes.

(Industrial product) Not a product of distillation, but made through a process of several different chemical reactions. It’s colourless, flammable, with a strong odour, and is used in the manufacture of a wide variety of industrial and household chemicals including antiseptics, disinfectants and detergents.

(Product of distillation) Methanol, or methyl alcohol, is a toxic type of alcohol, because our liver breaks down the methyl alcohol into formaldehyde and formic acid. Obviously, we don’t want to drink it, and it is easy to separate out during the early stages of the distilling process.

(Still) A type of still that has been used from ancient times. Alembics have a gourd-shaped body, with a cap and a long beak. The word comes from the Arabic al-ambic meaning ‘the still’. The word ‘ambic’ in turn, came from the Greek ambix, meaning ‘cup or beaker’ describing the shape of the pot. A traditional alembic still is one that adheres to this ancient design. It is also referred to as a pot still.

You can view a labelled diagram of a traditional alembic still on our About Distillation page.

(Still) There are many different types of column stills, but on this site this term ‘column still’ is usually used to refer to our alembic column stills, where a large column sits above the pot, and can be packed with plant material, for steam distillation of plant material.

Column alembic stills are very versatile, as you can steam-distil for essential oil and hydrosol, and use it to produce aromatic spirits. The upright column adds to the reflux in a distillation, and can be used to suspend gin botanicals above the neutral spirit in order to produce steam-distilled gin. In addition to straight steam-distillation, you can place plant material in both the column and in the pot (called a combo distillation), or remove the column altogether and use it as a traditional alembic.

You can view a labelled diagram of a column still on our About Distillation page.

(Still) An upright still, where the condenser forms part of the still, sitting as a cooling bucket at the top in the still’s ‘hat’. Its upright nature is good for distilling spirits, as it creates more reflux than a simple pot still, yielding slightly higher ABV outputs (around 85%). The bucket condenser is not as efficient at cooling as other stills, so distillations can tend to run hotter and faster than pot stills. Alquitar are also good for distilling barks and resins, where a higher distillation temperature is a benefit, rather than a disadvantage.

There is a labelled diagram of an alquitar on our About Distillation page.

(Of plants) A material obtained from a plant—including berry, leaf, flower, root, stem, or any part that can be used in distillation and extraction. Visit the Encyclopedia Botanica for in-depth profiles of widely-used aromatic botanicals.

(Of perfume) A family of perfumes that share the same basic scent accords, based on an ancient Mediterranean fragrance-style. Traditionally characterised by the contrast between the citrus top notes, and woody, mossy base notes. The word Chypre is French for Cyprus—which was perhaps where it was first made.

(Process) The process of repeated distillation of the aqueous part of an essential oil distillate. The aim is to separate out even more essential oil, gaining higher yields.

In essential oil distillations, some oil will remain dissolved in the aqueous part of the distillate, in the process of cohobation, this watery part is fed back into the boiling tank to be re-distilled, and separated further.

(Still) On this site this term ‘column still’ is usually used to refer to our alembic column stills, as it’s what we’re using in most of our courses. Distillers would most commonly use the term ‘column still’ to refer to a type of still with a column attachment that’s designed to promote reflux, strip out flavour and produce very high ABV spirits—like those types of home and commercial reflux stills used to create neutral spirit for vodka and gin-making.

(Still) See ‘alembic column’.

(Part of a still) A component of the distillation set up that is used for cooling the distillate, and converting it back into a liquid. Can be a worm, or bullet condenser, or in the case of the alquitar, a bucket. The condenser is attached to a cooling reservoir (usually a large container of water) or tap.

(Distillation equipment) In most distillation set ups a pump is used to circulate cooling water around the condenser. In our courses we use submersible water pumps, such as those used in aquariums.

(Organic compound) Chemical substances that are related to one another. In the context of distilling alcohol, congeners are minor compounds other than ethanol that occur naturally in alcohol beverages as a result of the fermenting and distilling processes. Congeners largely determine the colour and flavour of a drink—generally the darker the drink, the more congeners it has present (examples are rum, red wine, whiskey and brandy). Tequila is an exception—although pale in colour it has many more cogenors than other paler drinks like vodka.

(Of an alcohol distillation) When distilling alcohol from washes and ferments, the alcohol from this run can be divided into fractions—which are the heads (and foreshots), hearts and tails.

The part of the run that is selected for ageing or bottling is called the cut, which is determined by the distiller. Sometimes this will be just hearts, other times some of the heads and/or tails will be included to give a spirit a more flavour and character. It all depends on the type and style of spirit being made. Experienced distillers use their senses to determine cut off points.

See ‘fractions’ for more information on parts of an alcohol distillation.

(Process) A method of extraction, where plant matter is boiled or simmered in water to dissolve the compounds they contain. Coffee is an example of a decoction, while tea is an infusion.

(Product of distillation) The resulting liquid from a distillation. This is the part of the solution that’s removed as vapour and condensed during a distillation process.

(Process) The process of separating out the components of a substance, using heat, in a closed system (in this case a still).

(Product of distillation) Essential oil or EO is a dynamic compilation of different VOCs (volatile organic compounds), that will alter with season and harvest time, and the stage of some plant’s growth-cycle.

(Chemical compounds) Esters are some of the most common VOCs (volatile organic compounds). Esters are usually described as have sweet, fruity scents.

(Process) A collection of methods to isolate and concentrate flavour and aroma from plants and botanicals. Distillation is one method, others include decoction, infusion, tincture, enfleurage and cold extraction.

(Process) The process by which yeast converts sugars into alcohol. It’s quite magical.

(Still) Refers to stills that are particularly suited to refining or flavouring alcohol—especially gin.

(Of an alcohol distillation) the very first part of the distillation, that is discarded. When distilling small volumes, the foreshot is often simply included in the first heads shot—and also discarded. See ‘fractions’ for more information on parts of an alcohol distillation.

(Product) Once you introduce a preservative into a hydrosol, it then becomes a formulation and it’s no longer appropriate to name it ‘hydrosol’.

(Process) A type of distillation set-up used in commercial distillation. Developed because simple distillation is not efficient for separating liquids whose boiling points lie close to one another. In fractional distillation set-ups, the vapours from a distillation are repeatedly condensed and re-vaporised in an insulated vertical column.

(Of an alcohol distillation) When distilling alcohol from washes and ferments, the alcoholic distillate from this run can be divided into three main fractions—heads (and foreshots), hearts and tails. You can calculate the volume of each of these fractions using the initial volume of your wash.

Foreshot—the very first distillate that comes across. This should be discarded as it contains a range of chemicals and alcohols that are undesirable and potentially harmful. It’s a very small proportion of the total run (for example around 50-100ml of a 25L wash).

Heads—the first part of the distillation. Heads contain a higher concentration of those higher, more volatile compounds like methanol and acetone (which are harsh-smelling, like nail polish remover). Much of the heads will be discarded, however they also contain some good qualities, like fruity, floral esters, which you may want to keep.

Hearts—this is the good stuff, from the middle of the distillation. It’s mostly ethanol, and is the purest, cleanest part of your distillation.

Tails—distillate from the final part of the distillation. Lower in alcohol and higher in water and the heavier molecules like fusel oils and fatty acids that come over at higher temperatures.

Distillers must decide what parts of these fractions they want to include in their final product. Where you draw those lines are called your cuts, and the final product is called ‘the cut’.

(Process) An abbreviation for gas chromatography–mass spectrometry. This is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample (such as hydrosol or essential oil).

The Dutch word for juniper. Origin of the word ‘gin’.

The Dutch word for juniper. Origin of the word ‘gin’.

(Gin distillation process) Single and multi shot gins are both types of distilled gin, (though the proportion of distilled gin in them is different).

Single shot gin: A gin that only water is added to post-distillation to blend it to bottling strength. Also called ‘one shot’ distillations.

Multi shot gin: A gin where both neutral spirit (NS) and water are added post-distillation. In this process a distiller will use a greater amount of botanicals in the still than single shot, producing a gin with a much more concentrated flavour. NS is then added back to the gin to bring it back in line with the desired flavour profile and intensity, then it can be proofed and bottled.

The multi shot process produces much more gin per distillation than single shot methods, and is used to scale-up production. Multi shot gin recipes need to be optimised (tweaked to stay true to the flavour of the original recipe) as when you increase the volume of botanicals you can also change their interaction and resulting flavour.

There are pros and cons of both methods, and different distillers favour different approaches. Dr Anne Brock of Bermondsy Distillery addresses this brilliantly in her video here.

(perfume) a scent or perfume with edible notes, described as ‘olfactory desserts’. These scents are also known as ‘edible perfumes’ and are characterised by sugary-sweet notes like vanilla, caramel, chocolate, honey, cotton candy and bubblegum. This trend began in the 1990’s with Thierry Mugler’s Angel.

(Of an alcohol distillation) The middle part of the distillation. See ‘fractions’ for more information on parts of an alcohol distillation.

(Process) A distillation with water as the solvent. Plant material is placed in the pot of the still, along with warm or boiling water, the still is sealed and then heat is applied and the aromatic distillate is cooled and collected.

(Product of distillation) The aromatic waters produced from a hydro distillation. You can read more about what hydrosols do and don’t contain, and their uses in The Archive.

(Equipment) This is an instrument used to measure the ABV of a liquid. ABV should be taken at around 20°C. Tip: if your distillate is significantly warmer than this, you may get (higher) inaccurate readings.

(Property) The ability of a material to absorb water from its environment. Honey is an example of a hygroscopic substance.

(Process) Where hot water is poured over plant material to extract flavour. Teas are an infusion.

(Of alcohol) The cloudy property of some alcohols when over-saturated with particular VOC’s. Liquorice is a prime example of a botanical that will louche your gin if you add too much.

Louching is less likely to occur at higher ABV concentrations, as the VOCs in question are soluble in alcohol, but not water. When the ABV comes down and there is more water in the solution, these VOCs begin to separate out, causing cloudiness. That is why many gins with heavy botanical loads have higher ABVs (often between 42 and 46%).

(Part of a still) The extender that’s attached to the swans neck, this takes the distillate to the condenser. It can be tilted up or down and either tapered or straight. These variations are used to different effect, and depend on what you want to achieve in your distillation.

(Process) In distilling maceration refers to the process of soaking organic material in liquid (either water or ethanol) in order to soften it and to draw out its aromatic compounds. When hydro and steam distilling, macerating harder botanicals (like leaves with a waxy coating, some seeds, barks, roots and dried berries) for 24hrs before distilling them often helps increase the yield of essential oil, or the saturation of a hydrosol.

A tincture is a type of maceration that always involves ethanol as well as water.

In gin distilling maceration refers to the process of placing the gin botanicals inside the pot of the still with the neutral spirit, often leaving them to steep, and then distilling your gin—as opposed to vapour-infusion where the botanicals are suspended above the neutral spirit during the distillation.

Distillers will choose maceration or steam-distillation (or a combination of both) to make their product. The decision depends on the type of still selected, the flavour profile they’re aiming for and personal preference. When using a pot still (like the traditional alembic) maceration is often the only choice, as there is no option to suspend the botanicals above the spirit in a column or basket for steam infusion. Macerated gins are often ‘bigger’ with a stronger, punchier flavour profile (and because of this, can be more prone to louching) while vapour-infused gins can be more delicate and complex in comparison (though they can also pack in a lot of flavour).

Disambiguation: There is some confusion around the term when applied to gin, as non-distillers will sometimes produce what they call a ‘macerated gin’ by simply steeping botanicals in neutral spirit and then filtering them out—what is technically called a cold compound gin. These spirits are allowed to be labeled as gin (under EU law) but cannot be called ‘distilled’ or ‘London’ gin—so it pays to check if you want to know what you’re getting.

Additionally, sometimes the terms ‘infused gin’ or ‘favoured gin’ are used to refer to gin that has additional botanials or ingredients added post-distillation (like saffron gin).

(Substance) The remaining/spent material left in the pot after a distillation. It will contain any spent plant material that was used, as well as water and those molecules too heavy to come across in the distillation process (like those responsible for colour). The spent plant material from hydro and steam distillation can be composted, and the marc from some distillations (like red wine for eau de vie) can even be used for dying.

(Substance) A substance that dissolves solids or holds them in suspension. Another (and more archaic) word for ‘solvent’. Can also refer to menstral blood.

(Substance) A thick, jelly-like substance produced the leaves, seeds or roots of some plants. It’s is similar to plant gum, and contains polysaccharides and protein. Examples of mucilaginous plants include aloe, chia, marshmallow, cassava, figs, ocra and some seaweeds.

(Part of a still) The bubble-shaped chamber above the pot. This chamber allows the distillate to expand, condense and fall back into the pot during distillation—providing a small reflux action.

Involving the use of the sense organs (taste, smell, appearance, colour, feel). In our case we are using sensory information to evaluate the qualities of a food, ingredient or substance.

(Property of a molecule) In chemistry, molecules are either polar or nonpolar In simple terms ‘polar’ means oppositely charged and ‘nonpolar’ means equally charged. (In a nutshell, whether a molecule is polar or nonpolar depends on the type of bonds it has and its shape.)

Water is polar. Oils are nonpolar.

Polarity is useful to know about in distillation and extraction because it is the basis of solubility. Solubility is based on a principle of ‘like dissolves like’—meaning polar (water soluble) substances are soluble with each other, and nonpolar (soluble in fat and oil) substances are soluble with each other. Polar and nonpolar substances are immiscible.

(Part of a still) The part of the still that contains the liquid to be distilled. Can be any shape—round, onion or conical.

(Still) A widely-used style of still, who’s form is derived from the ancient alembic. It’s relatively simple, and consists of a pot, a swan’s neck and line arm and condenser. A traditional alembic is an example of a pot still. Pot stills are used for distilling washes and ferments, aromatic spirits and for hydro-distilling botanical material for hydrosol and essential oil.

The substance to be distilled is put in the pot and heated, travels up the lyne arm and into the condenser in a simple distillation. If further refinement is needed, then the product can be re-distilled. Alcohol is often re-distilled to refine the flavour and increase the ABV, though there are limits—with typical pot stills yielding a maximum of between 60-80% ABV. Many artisan distillers prefer pot stills for preserving taste and aroma, and will use other types of reflux column stills for producing their high-ABV, neutral spirit.

(Of alcohol) A US measurement of the amount of alcohol in an alcoholic beverage. US proof is twice the ABV percentage, so a spirit containing 50% ABV is called ‘100 proof’. Note we use ABV as a measurement on this site, not proof.

(Parts of a still) Simple joints in copper stills that require no special closure, as they just pushed firmly in place, and often taped. A benefit of push-fit joints is that they will simply pop off if the pressure inside the still becomes too great due to a blockage, rather than causing a dangerous explosion.

(Product of distillation) Similar to the mediaeval ‘spirituous waters’. When a plant material is tinctured then run through the still, the resulting product can be called a quintessence. The results are more refined than the tincture, and often are a good representation of the flavour a botanical will contribute to an aromatic spirit, so they are great to use when learning to blend.

(Process) In a distillation, reflux is when hot vapours come into contact with cooler material higher up in a still, condense and fall back into the pot. When reflux occurs in an alcohol distillation this successive evaporation and condensation will increase the final ABV of the distilled alcohol. This is also called rectification or enrichment.

Reflux also strips out flavour from distillate, as many VOCs will only vapourise once, and be left behind in the pot in this process. High levels of reflux is a benefit in alcohol distillations when purer, more neutral spirit is the aim. Here you want to maximise reflux (often with columns, plates and scrubbers). In other aromatic distillations (such as steam distilling essential oil) where you want flavour to come through, you should aim to minimise reflux.

With Alqutiar stills, their upright design promotes enough reflux to give slightly higher ABV readings than pot stills for alcohol distillations, but not enough reflux to strip out flavour in gin and coloured spirits.

(A substance) A solvent is a fluid (or mixture of fluids) which when macerating or tincturing extracts constituents from the plant matrix. Solubility is based on a principle of ‘like dissolves like’—meaning polar (water soluble) substances are soluble with each other, and nonpolar (soluble in fat and oil) substances are soluble with each other.

Water, oil and ethanol are all excellent solvents (and are the main solvents we use in aromatic distillation and extraction). Water is polar, so will extract (dissolve and mix) with the polar compounds in a substance, while oil is nonpolar. Alcohol contains both polar and nonpolar molecules, so can extract both polar and nonpolar compounds.

(Product of distillation) A distilled alcoholic drink of at least 20% ABV that contains no added sugar.

(Process) Where plant material is suspended above the pot, in the path of the steam or vapours instead of being boiled in the pot with the liquid. When making gin, steam (or vapour) distillation can be used to volatilize molecules in the botanicals, bringing forth more subtle flavour and aroma.

An instrument, or apparatus for distilling liquids. Can be many different shapes and sizes, and made from various materials such as copper, stainless steel glass or ceramics. There’s more information on the types of stills most commonly used on this site on the About Distillation page, and it’s explored more fully in our free course on Types of Stills.

(Property) A solution is considered supersaturated when it contains more than the maximum amount of a substance that it would usually contain at a given temperature. Honey, being 70% sugar and under 20% water, contains more sugars than would normally dissolve at room temperature, and it is considered a supersaturated solution. Bees are able to make it supersaturated by using a combination of enzymes and evaporation.

(Part of the still) The graceful arm that sits atop the pot, often connected via a dome (as in the case of a traditional alembic). The swan’s neck can be short, tall, straight, curved or tapered as the shape of a still depends on its purpose. Long, tapered necks help with separation and enriching of spirits.

(Of an alcohol distillation) The last part of the distillation. See ‘fractions’ for more information on parts of an alcohol distillation.

(Product) An extract of plant material dissolved in ethanol and water. When plant material is steeped in ethanol, it acts as a solvent, extracting the active ingredients. Concentrations of between 25–60% ethanol are common, but some may run as high as 90%.

The concentration needed depends on the requirements of different plant materials. For example for plants high in mucilage such as marshmallow, aloe and chickweed suit a tincture of 30% AVB. Plants like as nettle and peppermint are best at 60%, while calendula needs around 90% to extract the active compounds (which are in the resin).

(Process) In our context, vapourisation is used to describe the process of converting a liquid into a gas during the distillation process.

(In chemistry) Is a term used to describe how readily a substance vaporises. When at the same temperature and pressure, a substance with high volatility (like ethanol) is more likely to exist as a vapour than one with lower volatility (like water) that is more likely to remain a liquid.

The process of distillation relies on this principle, because when a solution is heated in a still, components of the mixture vapourise at different temperatures, thus allowing them to be separated out. Volatility is also important in perfume, as we humans smell something when aromatic vapours come into contact with receptors in our nose. Essential oils that vapourise quickly after application give what is referred to as ‘top notes’ to a perfume. While those that evaporate more slowly can linger on the skin, giving more lasting ‘heart’, or ‘base’ notes. Perfumers balance these notes when they create scents.

(Chemical compound) Volatile Organic Compounds. VOCs are responsible for the odour of scents and perfumes. In the plant world, VOCs are organic chemicals produced by plants to perform a variety of tasks, such as defence against insects and predators, attracting pollinators, plant-to-plant communication, thermo-tolerance and environmental stress adaptation. It’s these VOCs that we are extracting from plant material in aromatic distillation. As aroma plays a large role in our sense of taste, VOCs also have a large role in the flavour of food and beverage.

The most common VOCs include alkanes, carnonyls, alkenes, esters, alcohols, and acids.

(Part of a still) The copper coil that’s submerged in the condenser vessel, surrounded by continuously flowing cold water.