The facts about essential oils Part 2 of 5
Essential Oils are produced by distillation. Plant material such as leaves, flowers, woods etc. are arranged on plates in a receptacle, called a still. The still in a laboratory is usually made of glass but for large-scale production, stainless steel is the usual preferred material. You will however see in some old pictures that copper used to be used, but it is now regarded as too expensive for the process.
Water is filled in the bottom of the still and heated or alternatively steam is injected into the still from an outside boiler. Another method is a combination of water and steam. Pure steam is more efficient but some materials with a waxy nature such as flower petals may stick together, and in this case the water method is the preferred choice. The distillation of Rose Otto is such an example of where water distillation is more successfully used.
Hot steam ruptures the plant cells
Natural mixtures of the volatile chemicals that make up the essential oil are held in the cells of the plant material. The hot steam ruptures the cells and vaporizes the oils, thus releasing them into the path of the steam as it moves towards the outlet. The steam and volatile oil mixture is directed out of the still to a condenser to cool and revert back to water and oil.
A condenser in its simplest form is just a long pipe that allows the oil and steam mixture to cool down. This can be best seen on some farms in Indonesia where a drainpipe is used. In a modern still the condenser will have cold water flowing over the outside to make the cooling as efficient as possible and prevent losing oil into the atmosphere. The cooling water may be a coil that runs around the condenser or a water jacket (a bigger pipe closed over the condenser with an inlet and outlet for the cooling water).
Oil and water
The mixture drips from the condenser into a separating container also known as a "Florentine flask". The old adage "oil and water do not mix" is ever true in this case, because the oil and water do separate, with the oil floating to the top. Some oils sink and others such as vetiver will split into two fractions, part floating and part sinking. Separation is not always a simple matter depending on the plant and a number of techniques (usually closely guarded secrets) are used to improve the separation.
The oil gathered, the essential oil is a light color, as the color molecules in the plant material, such as chlorophyll are large and cannot be vaporized and carried over with the steam. Some darker colored oils such as vetiver and patchouli are dark because of their interaction between the iron material in the still and condenser (e.g. with simple steel drums or poorer grades of Stainless steel) rather than any color from the natural plant material.
An essential oil that is freshly distilled will have a gassy green note that on proper airing will fade after the first few weeks. This still note is from sulfuraceous products formed from reactions of the plant material and the hot steam in the still.
Lavender oil contains 500+ different chemicals
Most essential oils have hundreds of different chemicals in them. Lavender oil has over 500 different chemicals that make up the essential oil. We’ll explain more in another article, but in the meantime, keep those volatile chemicals off your face!