Not long after discovering the power and pleasures of aromatherapy, most enthusiasts eventually encounter warnings about using essential oils. This safety information includes cautions against using high percentages of phototoxic, sensitizing, or irritating oils in dermal blends.
Finding this safety information can be far easier than learning how to implement it. The general warnings to avoid using phototoxic essential oils in perfume or massage oils if you are going out in the sun may divide these oils into broad categories, leaving the beginner wondering what the difference is between strong and moderate phototoxic oils. More specific information detailing recommended maximum percentages for the total product can seem impossible to figure out during the blending process.
A self-calculating table can simplify the mathematical aspects of formulating safe and aesthetic aromatherapy blends. At the end of this article is a link to a downloadable Excel file originally created for my own use to assist with blend calculations. The following paragraphs describe its design and functions.
Bergamot is a widely loved oil. Its usefuless makes it a common ingredient in many different types of blends. Bergamot is also phototoxic. The recommended safe maximum level for bergamot in dermal applications is 0.4% of total product. With this level as an objective, the following examples demonstrate how to achieve this percentage in an oil blend using the self-calculating table as an aid.
Suppose you wanted to compose a balancing blend using juniperberry, bergamot, lavender, geranium, ylang ylang, and patchouli. The blend is first entered into the self-calculating table as 1 drop juniperberry, 2 drops bergamot, 6 drops lavender, 2 drops geranium, 3 drops ylang ylang, and 2 drops patchouli.
Diluting the blend to approximately 5% with 15 ml of the dilutant, reveals that the bergamot level is too high to be used safely in the sun, as the total product level proves to be 0.63%.
There are several ways to adjust the total product level of bergamot. The first way is to reduce the bergamot in the blend from 2 drops to 1 drop. When that number is changed in the table, the total product level of bergamot immediately drops to 0.32%, well into the safe range.
Another alternative would be to increase the dilutant until the bergamot level is safe: Adjusting the dilutant volume from 15 ml to 24 ml changes the total product bergamot level to 0.4%.
This adjustment also lowers the percent dilution for the entire blend from 5.06% to 3.23%.
And yet another way to make the blend sun safe is to use 1 drop of furocoumarin free (FCF) bergamot in place of regular bergamot, which would again return the total product percentage of (whole) bergamot to 0.32%.
Another blend characteristic returned by the self-calculating table is the percentages of top, middle, and base notes. Many experts in the aromatic arts recommend various ratios of these notes for creating a balanced blend. I have read many guidelines, most often near the proportions of 1:2:1 (25%, 50%, 25%), 2:3:2 (28.57%, 42.86%, 28.57%), or 4:3:3 (40%, 30%, 30%). Whatever proportions you select as your goal, the table will track the fluctuating percentages as you construct or alter your blend.
And lastly, the bottom figure in the table returns the total volume of the product in milliliters so that you know the size of the bottle you need.
To put this tool to work for you, download a copy of the file and key in your volume of dilutant in milliliters and oils in numbers of drops, fillng in only the white areas.
Click below to go to the download page graciously provided by Rob Stitt, one of AGORA’s technostar members.
“Geometry as a contemplative practice is personified by an elegant and refined woman, for geometry functions as an intuitive, synthesizing, creative yet exact activity of mind associated with the feminine principle.
“Arithmetic is also personified as a woman, but not as grand and noble in attire as Geometry, perhaps symbolically indicating that Geometry was considered as a higher order of knowledge. On her thighs . . . are two geometric progressions. The first series, 1, 2, 4, 8, goes doen the left thigh, associating the even numbers with the feminine, passive side of the body. The second series, 1, 3, 9, 27, goes down the right thigh, associating odd numbers with the masculine active side . . . .” —Robert Lawlor, Sacred Geometry.
The Excel Spreadsheet referenced in this article can be downloaded from the download link at the bottom of the page. For optimum use of the spreadsheet the first time you use it, it is recommended that you open the spreadsheet side-by-side with a reduced size window containing this page.