There are no rigid rules, only possibilities. For this reason, no two aromatherapists will offer the same prescription to a person suffering from a given set of symptoms. Even if they come up with the same essential oils, chances are that the proportions of each oil in the aromatic prescription will be different. Indeed, it seems that the possible blending permutations are limitless! Nevertheless, it is still possible to offer a few guidelines which, no doubt, you will eventually surpass.
Generally speaking, 'families' of essences tend to blend well together, albeit in a rather conservative way; for instance, herbs (clary sage, lavender, marjoram, rosemary), citrus (bergamot, orange, lemon, lime, mandarin), flowers (rose, ylang ylang, neroli), spices (coriander, ginger, cinnamon), resins (frankincense, elemi, gal-banum), woods (sandalwood, cypress, cedarwood). Other compatible aromas are spices with citrus (coriander and bergamot), resins with flowers and citrus (frankincense with rose and lemon). Woods and resins are a good match too: frankincense and cedarwood is a classic.
You could also try marrying wildly differing personalities, such as pungent black pepper or ginger with rose otto; the ancient and mysterious frankincense with the common or garden lavender; the bitter-sweet neroli with a hint of earthy vetiver or patchouli; the sweet scent of ylang ylang with the sharp scent of lemon, or whatever combination your developing sense of smell may suggest.
Odour Intensity
Certain essences are highly odoriferous, which means they will predominate your blends unless used in tiny amounts. Take the piercing aroma of lemongrass, for example; the oil is categorized as a top to middle note. This means it is highly volatile and will evaporate much more speedily than oils which resonate further down the odor scale. Yet add just a fraction too much lemongrass to a blend containing the less volatile middle to base notes, say, cypress and sandalwood, and the lemongrass will take over. However, if the blend is not used up immediately, the more tenacious sandalwood and cypress will eventually win through - even though their aromas are masked at the outset. So a highly odoriferous oil is not necessarily a base note, as is commonly believed; rather, it has an intense, though sometimes relatively short-lived, aroma.
If blended in the correct proportions, a mixture of lemongrass, cypress and sandalwood will become an harmonious scent with no single essence predominating. The more tenacious essences will intermingle with the lemongrass - rather than being swamped by it - and will slow down its evaporation rate. Aromatherapists describe such a perfectly balanced mixture as a 'synergistic blend'. Quite apart from the aesthetic element, a synergistic blend is generally believed to be more efficacious. In fact, this intuitive understanding has been partially vindicated by science.
Generally, when blending highly odoriferous essences with less odor-intensive oils it is important to start with a tiny amount of the most powerful-smelling oil and to add other essences drop by drop until you achieve the desired fragrance. For example, when creating a massage oil blend, you could begin with just one drop of tagetes or galbanum to 25-30 ml of base oil (very much lower than a 0.5 per cent dilution!). The less odoriferous essences can be added afterwards, in concentrations of between 1 and 2 per cent. But it is advisable to add just one drop at a time, mixing well and smelling as you go. You may then find, for example, that three drops of lavender and six drops of bergamot essence, together with the single drop of tagetes or galbanum, make an harmonious brew. If you disagree, adjust the ratio of essential oils according to your own aroma preference.
When using highly odoriferous oils in applications other than for massage, such as baths, steam inhalations and compresses, unless the essences are first diluted in a base oil (not always appropriate) it is impossible to give precise quantities. As a rule of thumb, it is advisable to use no more than a single drop, perhaps blended with a few drops of another compatible oil.
A Selection Of 'Possibles'
When choosing oils for yourself it is relatively easy to compose a therapeutic blend which also suits your aroma preference. When deciding upon oils for another person, however, the process can be a little more difficult - especially if you have a limited selection. Even so, it may be helpful to illustrate how an aromatherapist might approach the task.
Although every aromatherapist will have their own method for determining which oils to use, the initial consultation always involves taking a thorough case history, as well as establishing the current emotional and physical state of the client. The aromatherapist may then refer to a therapeutic cross-reference of essential oils and/or use their intuition and knowledge to pick out a selection of 'possibles' - usually between three and six oils. The client may then be given the opportunity to smell each of the chosen oils and to decide which they like best. If more than one essence is to be used for the treatment, the aromatherapist will then apply their skill and intuition in preparing a test blend. If the client is happy with the mixture, then the blend will be used for that particular treatment (different combinations of oils may be used in subsequent treatments to suit the ever-changing pattern of the mind/body). If the client dislikes the blend, a good aromatherapist will try one or two other permutations until they hit upon a blend which the client finds agreeable. Although this may sound rather hit-or-miss - or even 'client-dominated' - in my own experience, the method works extremely well.
Incompatible Aromas
Certain essential oils when mixed together seem to 'fight' or refuse to merge into an harmonious whole. Examples of incompatible aromas (at least to my nose) include ylang ylang/tea tree, fennel/clove, peppermint/fennel, cinnamon leaf/sweet thyme, Roman or German chamomile/myrrh, peppermint/orange, patchouli/ German chamomile. As an experiment, try mixing some of these sparring partners (or any other unlikely sounding blend you can think of) and judge for yourself. Should you actually enjoy any of the aforementioned mixtures, then do feel free to ignore my comments about their so-called incompatibility. Indeed, an individual's perception of what is 'good' or 'not good' is highly subjective, and should be respected as such. Although there may well be a biochemical explanation for the 'incompatibility' of certain essences, there is no need to hold a degree in chemistry to perfect the art of blending. It is enough to apply your own aromatic good taste.
