Steam Distillation of Plants: One Process, Two Products, and a Million Possiblities

Over the past many years, plants have continued to fascinate me - not so much for their beauty (which is, of course, a joy) but for their endless uses and benefits.

Today, we're going to focus on a process used to 'capture the power' of plants. This single process results in 2 end products - each carrying their own part of the plants different components.

This process is called distillation.

Approximately a Gazillion Ages Ago

Even though distillation is so old it's unclear how, when, and where it all started, there are some records to be found. Many historians agree distillation has been around for well over 2000 years – while some believe it goes back as far as 5000 years.

The first printed book on 'distilling waters to help treat ailments' is dated as far back as 1477.

In short, we humans have been extracting actives and other 'goodies' from plants for different uses for a very long time.


Distilling can be done 3 ways:
  • steam 
  • water 
  • water-and-steam

The method for any particular process is often decided by the plant material itself. Some plants can 'take a beating' while others require a more gentle touch. For example, many flowers will tend to clump together if steam-distilled making it difficult for the steam to pass through. Flowers will therefore often require water distillation. Some plants (typically herbs and leaves) are placed above the water on a grid – this method is known as water-and-steam distillation.

Steam distillation – where steam is injected directly into the still – is the most commonly used method.

How it Happens

Below is a super simplified graphic of what happens during distillation.  Plant material is placed in a still with water and the mixture is heated.

The resulting steam carries both oil and water-soluble components of the plant with it. The steam travels along en enclosed system of tubes/pipes and through a cooling process where it returns to a liquid state – now rich with 'plant power'.

The final precious liquids end in a receptacle where they are collected.

The water-soluble (and a minute amount of the oil-soluble) constituents of the plants are transferred to the resulting water. This water is known as hydrosol or hydrolate.

The oil-soluble constituents released from the plant during distillation are known as essential oils. The essential oils float on the top of the hydrosol (unless it is clove being distilled. Clove essential oil is actually heavier than water and will fall to the bottom).

Both hydrosols and essential oils can be used in a plethora of ways - both for skin and hair care.

Olfactory Surprises 

One might think it would be a given that any essential oil and hydrosol from the same plant would have the same scent and properties.

Not necessarily so.

Example 1: Lavender

Here's a fun little exercise. Try sniffing a lavender hydrosol and then the essential oil. There's a world of difference between the 2. The oil smells like lavender 'as we all know it' while a true lavender hydrosol has a slightly murky, mustier scent - only slightly reminiscent of lavender.

My first order of lavender hydrosol was a real disappointment. I actually thought the hydrosol had gone off. It wasn't until after several repeat orders with the exact same result I had to accept the fact that – as much as I love the essential oil – the scent of lavender hydrosol just doesn't appeal to me.

Example 2: Orange Blossom (Neroli)

Try sniffing orange blossom hydrosol and then the oil. One would naturally expect any hydrosol to have a fainter scent than the essential oil. With orange blossom, it is quite the opposite. The scent of the hydrosol is so incredibly potent that it will easily overpower everything else in a blend. The scent of the oil is barely discernible by comparison.

Floral Water - Buyer Beware

If someone presents you with a liquid they claim is lavender hydrosol and it smells like the essential oil - only more faint, then you are not sniffing a hydrosol, but a floral water or linen water. Floral (or linen) water is not the result of a distillation process. It is made by adding essential oil and a dispersant to distilled water. It is not a true hydrosol and it never will be.

Floral waters have many uses as well, but must not be confused with hydrosols.

Do Tell

Do you use hydrosols? Which are your faves?

Find More About Distillation and Extraction Methods

Wiley Online Library: the Early history of Distillation
Ancient History: The beginnings of medicine
History of Distillation
Distilling History- Montgomery Distillers
NAHA - On steam distillation and other extraction methods 


MarĂ­a said…
Hydrosols are so versatile! As liquid phase on emulsions (endless possibilities), toners, micellar waters, hair rinse waters, masks...
My favourites are rose, lemon verbena (Lippia citriodora), lemon balm (Melissa officials) and spearmint. Also German camomile ;)
LisaLise said…
You and I have several of the same favorites Maria! I find them excellent for all the same things you do as well.