Blending essential oils can range from the straightforward use of classic, well established blends; or there is an enormous rabbit hole of perfumery information which can be very intoxicating to venture into.
To look at some basic aspects of blending essential oils for the purposes of cosmetics; we must leave all thoughts of aromatherapy and therapeutic uses at the door. In cosmetic products we are concerned only with the final scent. The only question we should be asking is “Will my customers find this scent attractive?”
The term ‘essential oils’ is often used to describe all plant derived scents. Methods of extraction can be (a process of separating the scented oil from the botanical matter by using steam and condensation), the use of solvents to create absolutes, the cold pressing of plant matter (eg an expressed citrus peel) or carbon dioxide. Dilutions are often provided for very expensive oils such as 5% rose absolute or carbon dioxide extracted vanilla in sunflower oil and the thickness of myrrh resin may be addressed by including a solvent so it is ‘thinned’ and pourable.
Classic blends are always a reliable way of using essential oils without committing to testing quantities of expensive oils. Keep an eye on products you may see on the high street for inspiration and check ingredient lists for any disclosure of essential oils by their botanical name. Blends such as Lavender & Bergamot and Rosemary & Peppermint have a well established history and are not expensive oils to use. Consider replacement options, as an example, if you really want a rose (both the essential oil and absolute are highly restricted due to methyl eugenol contained in them) then would a rose geranium of the Perlargonium graveolens or roseum be an acceptable alternative?
If you want to completely ‘start from scratch’ in creating your own essential oil scent blends then while there are no rules as such, there are some established guidelines. For longevity, scent will usually need top, middle (also called a heart note) and base notes which are relevant to how quickly they will evaporate. As a very general rule of thumb, citrus oils are usually top notes, florals, spice and herbaceous oils can be middle notes with woods and resins as base notes. You will find many classifications available as lists or essential oil wheels providing blend suggestions. When you have your final, perfect scent, then you can have what is known in perfumery as an accord. A, distinct, individual scent that differs from the original ingredients.
There are many suggestions for testing blends. Adding drops into a container and leaving it sealed for a couple of days or adding drops onto a piece of absorbent paper and leaving that in a sealed container – out of sunlight as we know this can deteriorate essential oils. But while these are all excellent ideas; we really need to remember that when we use scent in a cosmetic product; the product will usually be exposed to some level of heat; be it the body temperature of a balm applied to skin or the warm water of a bath or shower product. This exposure to heat can cause a bloom of fragrance and action upon the different notes that will be quite distinct to the ‘cold’ scent of an oil blend test. This is our suggestion for testing blends:
- Mix your blend in drops initially in a small quantity as per your ratio of oils to test (eg 15 drops lavender, 10 drops chamomile, 5 drops clary sage)
- Stir well then start to separate your mix into different testing options
- Cold test – add a couple of drops of the mixture onto a small piece of blotting paper and pop that paper into a little screw top container before placing it in a suitable area to store
- Body temperature test for leave on products – add a small quantity of the mixture at 1% into a carrier oil and after stirring well, apply a small amount onto your skin (not the back of hands as we wash those regularly) and sniff away as you go about your day (VERY roughly, 20 drops = 1ml so calculate accordingly). Store the dilution in a suitable area and test again every couple of days
- Heat test – add a few drops of the blend into an essential oil burner with a little water and see how the blend develops as it is warmed by the tea light or you can use a small double boiler system to note the fragrance of the blend when it is heated
The website Aroma Web is a very useful source of inspiration and general information for essential oils and blending but please remember that cosmetics in the EU and UK are produced under very strict legislation which means some essential oils may be restricted to much lower amounts than can be used in other areas of the world. As a general consideration we can think about adding a 3% total of essential oils (single or a blend) into a rinse off product such as soap or bath bombs and 1% in leave on products such as body butters and other skin care but this is subject to any individual essential oil restrictions that may be applied by your assessing chemist as part of the process to obtain a CPSR.
Do a little research, have a little play and most of all; enjoy the process of creating your own, individual, essential oil blends.
