The Encyclopedia of Essential Oils (5 page)

Essential oils are blended principally for two reasons: for their medical effects or to create a perfume. When we are using pure essential oils, these are not two different categories but rather two ends of a scale. At one end of the scale we are dealing with the therapeutic action on a purely physical condition such as backache – at the other end, with an emotional or aesthetic response to a particular odour. But, of course, the individual who is suffering from lumbago also has a psychic or emotional disposition of which they may or may not be aware, which will naturally respond in a more subtle way to a particular blend of oils. Similarly, when we create a personal perfume which expresses the unique personality of an individual through fragrance, it has a generally remedial effect on the person as a whole.

Therefore, when we are blending oils, even if it is principally for their medicinal properties, it is always worth keeping the fragrance in mind. It is more pleasing to use a remedy that smells attractive to the individual concerned. Some scents can be quite incompatible – a predominantly floral blend, for example, would be unacceptable to the majority of men. How to choose the oils and combine them is very much a matter of personal choice, but there are some useful guidelines to keep in mind.

For therapeutic purposes, essential oils are usually diluted before being applied to the skin. To make a massage or body oil the essential oil or oils should first be mixed with a light base oil such as grapeseed or sweet almond oil. (See also Chapter 4. How to Use Essential Oils at Home.) Other oils that could be used for the base include sunflower, hazelnut, safflower, peanut, soya or corn oil – mineral oils, however, are best avoided. The more nourishing and generally thicker oils which include jojoba, avocado, peach or apricot kernel, borage, olive, sesame, evening primrose and also some infused oils such as calendula or St Johns wort can also be included (up to about 10 per cent) in the treatment of specific conditions. A small quantity of wheatgerm oil (about 5 per cent) added to the blend will help to preserve it.

The essential oil content in a blend should usually be between 1 per cent and 3 per cent depending on the type of disorder; as a general rule, physical ailments demand a stronger concentration than the more emotional or nervous conditions. Some oils, such as the high quality florals including rose and jasmine, have more diffusive power than most other essences – this means that a very small percentage is all that is needed to have a powerful effect, or to influence the character of an entire blend.

The proportions of each essential oil in a blend can also be vital to the effectiveness of the remedy as a whole (many aromatherapy books contain exact recipes for specific disorders). Some oils blended together have a mutually enhancing effect upon one another, so that the whole is greater than the sum of the parts: for example, the anti-inflammatory action of chamomile is supported by being mixed with lavender. When the blended oils are working harmoniously together, then the combination is called a ‘synergy’. ‘In order to create a good synergy, you must take into account not only the symptom to be treated but also the underlying cause of the disorder, the biological terrain, and the psychological or emotional factors involved.’
¹⁷

This is very much the conclusion that Madame Maury reached when she prescribed an IP (or Individual Prescription) for her patients, in which the blended essences were matched not only to their physical requirements, but also to their circumstances and temperament.

In general, oils of the same botanical family blend well together. Also those which share common constituents usually mix well, such as the camphoraceous oils containing a good percentage of cineol, which includes all the members of the Myrtaceae group (eucalyptus, tea tree, cajeput, myrtle, etc.) but also many herbs including spike lavender, rosemary and Spanish sage. Most floral fragrances blend well together, as do the woods, balsams, citrus oils and spices, etc. Rosewood and linaloe combine well together, although they belong to different botanical families, since they both contain a high proportion of linalol and linalyl acetate.

Some oils such as rose, jasmine, oakmoss and lavender seem to enhance just about any blend, and can be found (mainly in an adulterated form) amongst the ingredients of most commercial perfumes – ‘no perfume without rose’.

Some combinations, on the other hand, have an inhibiting power over one another. Essences with a predominance of aldehydes (such as citronella oil containing citronellal), those with mainly ketones (such as sage containing thujone) and those with high amounts of phenols (such as clove oil containing eugenol), when combined with each other tend to ‘pull’ in different directions. However, knowing the precise chemical make-up of each oil is not necessary for creating a good synergy; it is also a matter of getting to know the ‘character’ of each essential oil and trusting the intuition.

In the nineteenth century, a Frenchman called Piesse instigated a new approach to perfumery work by classifying odours according to the notes in a musical scale. He transposed the idea of musical harmony into the realm of fragrances where the corresponding notes to each scent formed perfectly balanced chords or harmonics when they were combined together.

The purist vision of Piesse has long since been discarded but continues to provide inspiration in perfumery work today since the oils are still divided into ‘top’, ‘middle’ and ‘base’ notes.

The top note
has a fresh, light quality which is immediately apparent, due to the fast evaporation rate.

The middle note
is the heart of the fragrance, which usually forms the bulk of the blend, whose scent emerges some time after the first impression.

The base note
is a rich, heavy scent that emerges slowly and lingers. It also acts as a fixative to stop the lighter oils from dispersing too quickly.

Ylang ylang is said to be a well-balanced perfume oil in its own right. It could be described as having a very powerful sweet floral top note, a creamy-rich middle note, and a soft floral, slightly spicy base note.

For the sake of simplicity, each essential oil is also classified in this way according to its dominant character – although there are many different opinions on the matter! The following list provides nothing more than a general idea:

Top notes
tea tree, eucalyptus, mandarin, lemon, basil

Middle notes
geranium, lavender, marjoram, rosewood, rosemary

Base notes
patchouli, rose, jasmine, benzoin, frankincense, myrrh

A well-balanced perfume is said to contain elements from each of these different categories, the quantities of each determining whether it is a heavy oriental-type scent or a light floral aroma. Although this theory is used primarily in fragrance work, the same principles can also be applied to aromatherapy and personalized remedies.

Creating a perfume or an individual fragrance is like painting a picture or making a meal: it needs the correct balance of colours or flavours, neither too sparse nor too crowded; it also generally has a theme. A perfume should have a focus around which other fragrances unite. For example, if we want to create an oriental fragrance or a heart-warming, elevating type of blend, then woody or musky oils and balsams will play a central role. The exotic perfume ‘Shalimar’ by Guerlain contains a predominance of such oils, containing among its ingredients Peru balsam, benzoin, opopanax, vanilla, patchouli, rose, jasmine, orris and vetiver as well as rosewood, lemon, bergamot and mandarin.

Home perfumes need not be so complex: rose and benzoin (base notes), rosewood (middle note) and bergamot (top note) would together make a pleasing combination with an uplifting, warming quality. Rosewood is an oil which can be used to round off sharp edges, as well as providing a good bridge between citrus and floral or woody-balsamic notes. The overall character of a perfume also benefits from unusual or diverse combinations which can help to give personality to an otherwise ‘flat’ fragrance. A floral fragrance with a hint of spice such as clove or cinnamon can add depth and interest, but the percentage of such additions is critical because they can easily upset the balance.

A skilled perfumier can identify some 30,000 different odours, but to begin with it is best to become familiar with a few common oils and develop
from there. By initially keeping to a maximum of three or four oils per blend it is possible to keep in touch with their individual scents and qualities, then slowly build up a personal vocabulary of odours.

Most commercial perfumes are diluted in alcohol; a typical eau de cologne contains no more than 3–5 per cent aromatic material, usually synthetic. Home-made perfumes are best made up simply of pure essences, which last longer and may be used neat on the skin or in the bath, etc.

Personal experimentation is the only way to really find out what works, for the unique quality of essential oils is that they possess an array of therapeutic possibilities complemented by a vast spectrum of fragrances which can be mixed in endless combinations! In the words of John Steele:

Creative blending is an aesthetic alchemical process … learning to ‘listen through the nose’. To listen is to be receptive, to be empty. Every drop shifts the orchestration of olfactory vibrations, the ‘song of the blend’. A blend is not made at once, rather it evolves, it organically grows and interacts not only with the essential oils, but also with the blender.
¹⁸

Over thirty families of plants, with some ninety species, represent the main oil-producing group. The majority of spices (allspice, cardomon, clove, nutmeg, ginger, etc.) originate in tropical countries; conversely, the majority of herbs grow in temperate climates (bay, cumin, dill, marjoram, fennel, lavender, rosemary, thyme, etc.). The same plant grown in a different region and under different conditions can produce essential oils of widely diverse characteristics, which are known as ‘chemotypes’. Common thyme
(Thymus vulgaris)
, for example, produces several chemotypes depending on the conditions of its growth and dominant constituent, notably the citral or linalol types, the thuyanol type, and the thymol or carvacrol type. It is therefore important not only to know the botanical name of the plant from which an oil has been produced, but also its place of origin and main constituents. One of the main ways of defining the qualities of a particular oil and checking its purity is to ascertain the specific blend of components and look at its chemical character.

In general, essential oils consist of chemical compounds which have hydrogen, carbon and oxygen as their building blocks. These can be subdivided into two groups: the hydrocarbons which are made up almost exclusively of
terpenes
(monoterpenes, sesquiterpenes and diterpenes); and the oxygenated compounds, mainly
esters, aldehydes, ketones, alcohols, phenols
and
oxides;
acids, lactones, sulphur and nitrogen compounds are sometimes also present.

Common terpene hydrocarbons include limonene (antiviral, found in 90 per cent of citrus oils) and pinene (antiseptic, found in high proportions in pine and turpentine oils); also camphene, cadinene, caryophyllene, cedrene, dipentene, phellandrene, terpinene, sabinene, and myrcene among others. Some sesquiterpenes, such as chamazulene and farnesol (both found in chamomile oil), have been the object of great interest recently due to their outstanding anti-inflammatory and bactericidal properties.

Probably the most widespread group found in essential oils, which includes linalyl acetate (found in bergamot, clary sage and lavender), and geranyl acetate (found in sweet marjoram). They are characteristically fungicidal and sedative, often having a fruity aroma. Other esters include bornyl acetate, eugenyl acetate and lavendulyl acetate.

Citral, citronellal and neral are important aldehydes found notably in lemon-scented oils such as melissa, lemongrass, lemon verbena, lemon-scented eucalyptus, citronella etc. Aldehydes in general have a sedative effect; citral has been found to have specifically antiseptic properties. Other aldehydes include benzaldehyde, cinnamic aldehyde, cuminic aldehyde and perillaldehyde.

Some of the most common toxic constituents are ketones, such as thujone
found in mugwort, tansy, sage and wormwood; and pulegone found in pennyroyal and buchu – but this does not mean that
all
ketones are dangerous. Non-toxic ketones include jasmone found in jasmine, and fenchone in fennel oil. Generally considered to ease congestion and aid the flow of mucus, ketones are often found in plants which are used for upper respiratory complaints, such as hyssop and sage. Other ketones include camphor, carvone, menthone, methyl nonyl ketone and pinocamphone.

One of the most useful groups of compounds, tending to have good antiseptic and antiviral properties with an uplifting quality; they are also generally non-toxic. Some of the most common terpene alcohols include linalol (found in rosewood, linaloe and lavender), citronellol (found in rose, lemon eucalyptus and geranium) and geraniol (found in palmarosa); also borneol, menthol, nerol, terpineol, farnesol, vetiverol, benzyl alcohol and cedrol among others.

These tend to have a bactericidal and strongly stimulating effect, but can be skin irritants. Common phenols include eugenol (found in clove and West Indian bay), thymol (found in thyme), carvacrol (found in oregano and savory); also methyl eugenol, methyl chavicol, anethole, safrole, myristicin and apiol among others.

By far the most important oxide is cineol (or eucalyptol) which stands virtually in a class of its own. It has an expectorant effect, well known as the principal constituent of eucalyptus oil. It is also found in a wide range of other oils, especially those of a camphoraceous nature such as rosemary, bay laurel, tea tree and cajeput. Other oxides include linalol oxide found in hyssop (decumbent variety), ascaridol, bisabolol oxide and bisabolone oxide.

In general, the term ‘essential oil’ is rather loosely applied to all aromatic products or extracts derived from natural sources, including concretes, resinoids and absolutes which contain a mixture of volatile and non-volatile components, such as wax or resin. This is not strictly accurate, since they are only partially composed of essential oils and are obtained by different methods of production, which include the use of solvents or more recently,

carbon dioxide extraction. However, it is always the essential oil content in a given product that accounts for its aromatic quality.

Some plant materials, especially flowers, are subject to deterioration and should be processed as soon as possible after harvesting; others, including seeds and roots, are either stored or transported for extraction, often to Europe or America. The method of extraction which is employed depends on the quality of the material which is being used, and the type of aromatic product that is required.

An essential oil is extracted from the plant material by two main methods: by simple expression or pressure, as is the case with most of the citrus oils including lemon and bergamot, or by steam, water or dry distillation. The majority of oils such as lavender, myrrh, sandalwood and cinnamon are produced by steam distillation. This process only isolates the volatile and water-insoluble parts of a plant – many other (often valuable) constituents, such as tannins, mucilage and bitters are consequently excluded from the essential oil. Sometimes the resulting oil is redistilled or
rectified
to get rid of any remaining non-volatile matter; some essential oils are redistilled at different temperatures to obtain certain constituents and exclude others – as with camphor which is split into three fractions, white, yellow and brown.

Essential oils are usually liquid, but can also be solid (orris) or semi-solid according to temperature (rose). They dissolve in pure alcohol, fats and oils but not in water and, unlike the so-called ‘fixed’ plant oils (such as olive oil), they evaporate when exposed to air leaving no oily residue behind.

Concretes are prepared almost exclusively from raw materials of vegetable origin, such as the bark, flower, leaf, herb or root. The aromatic plant material is subjected to extraction by hydrocarbon-type solvents, rather than distillation or expression. This is necessary when the essential oil is adversely affected by hot water and steam, as is the case with jasmine; it also produces a more true-to-nature fragrance. Some plants, such as lavender and clary sage, are either
steam distilled to produce an essential oil or used to produce a concrete by solvent extraction. The remaining residue is usually solid and of a waxy non-crystalline consistency.

Most concretes contain about 50 per cent wax, 50 per cent volatile oil, such as jasmine; in rare cases, as with ylang ylang, the concrete is liquid and contains about 80 per cent essential oil, 20 per cent wax. The advantage of concretes is that they are more stable and concentrated than pure essential oils.

Resinoids are prepared from natural resinous material by extraction with a hydrocarbon solvent, such as petroleum ether or hexane. In contradistinction to concretes, the resinoids are prepared from dead organic material, whereas concretes are derived from previously live tissue. Typical resinous materials are balsams (Peru balsam or benzoin), resins (mastic and amber), oleoresins (copaiba balsam and turpentine) and oleo gum resins (frankincense and myrrh). Resinoids can be viscous liquids, semi-solid or solid, but are usually homogeneous masses of non-crystalline character. Occasionally the alcohol-soluble fraction of a resinoid is called an absolute.

Some resinous materials like frankincense and myrrh are used either to make an essential oil by steam distillation or a resin absolute by alcohol extraction directly from the crude oleo gum resin. Benzoin, on the other hand, is insufficiently volatile to produce an essential oil by distillation: liquid benzoin is often simply a benzoin resinoid dissolved in a suitable solvent or plasticizing diluent.

Like concretes, resinoids are employed in perfumery as fixatives to prolong the effect of the fragrance.

An absolute is obtained from the concrete by a second process of solvent extraction, using pure alcohol (ethanol) in which the unwanted wax is only slightly soluble. An absolute is usually subjected to repeated treatment with alcohol; even so, as is the case with orange flower absolute, a small proportion of the wax remains. Absolutes can be further processed by molecular distillation which removes every last trace of non-volatile matter. The alcohol is recovered by evaporation which requires a gentle vacuum towards the end of the process. Some absolutes, however, will still retain traces of ethyl alcohol, at about 2 per cent or less, and are not recommended for therapeutic work because of these impurities.

Absolutes are usually highly concentrated viscous liquids, but they can in some cases be solid or semi-solid (clary sage absolute). In recent years, much research has been devoted to the extraction of essential oils and aromatic materials using liquid carbon dioxide; oils produced in this manner are of excellent odour quality and are entirely free of unwanted solvent residues or non-volatile matter.

True pomades are the products of a process known as enfleurage, which is virtually obsolete today. This was once the principal method for obtaining aromatic materials from flowers that continued to produce perfume long after they were cut. A glass plate was covered in a thin coating of specially prepared and odourless fat, called a
chassis.
The freshly cut flowers, such as jasmine or tuberose, were individually laid in the fat which became saturated with their volatile oils. The
chassis
would be frequently renewed with fresh material throughout the harvest. Eventually the fragrance-saturated fat, known as pomade, would be treated by extraction with alcohol to produce the pure absolute or perfume.

Many perfumes or oils, once obtained from flowers such as carnation, gardenia and lilac, are nowadays produced almost entirely synthetically. In the pharmaceutical industry these chemically constructed products are called ‘nature identical’. The perfumery and flavouring industries require continuity in their products and naturally occurring substances are always subject to change, due to seasonal conditions. However, the so-called ‘nature identical’ products and the naturally occurring essential oils are of an entirely different character, which is reflected in their relative costs – the synthetic types being much cheaper to produce than the genuine ones.

Many aromatic oils, such as lavender or geranium, contain a relatively small number of major constituents, several minor constituents and also a very large number of trace elements. To reconstruct such a complex combination of components including all the trace elements, would be virtually impossible. Most ‘nature identical’ oils are said to be only about 96 per cent pure or accurate, yet it is the remaining 4 per cent, the trace elements, that often really define a particular fragrance. Such is the case with galbanum oil where the pyrazines, present at rather less than 0.1 per cent, are responsible for the powerful green odour of the oil.

It is also the specific combination of constituents in a real essential oil, including the trace elements, which give it value therapeutically. The reason for this might be that these minute amounts of trace elements have a synergistic or controlling effect on the main ones. For example, there are over 300 different constituents in rose, some of which have not yet been identified, which is why synthetic rose oil is unconvincing. ‘Nature identical’ oils cannot be used therapeutically as substitutes for the naturally occurring aromatic materials, not only because the subtle balance of constituents is lost but also because they lack the vital ‘life force’ of oils of natural origin.