When combining essential oils, the goal is to create a synergistic effect where the final blend is more effective than the individual oils alone. Blending requires a thoughtful approach to both the aromatic profile and the chemical compatibility of the oils selected. This allows you to customize aromas and properties for diffusion or topical application. Understanding scent grouping and molecular weight helps ensure mixtures are pleasing and consistent. This guide explores the rules of chemistry and structure that determine which essential oils are good to mix together.
The Chemistry of Scent Families
The most straightforward way to begin blending is by considering an oil’s scent family, which groups oils with similar aromatic characteristics. These groupings are based on the dominant notes perceived by the nose, and oils from the same or neighboring families generally pair well together. The major categories include Floral, Citrus, Woody, Herbaceous, Spicy, and Resinous oils, each offering a distinct palette for blending.
Oils belonging to the Citrus family, such as lemon or sweet orange, are bright and uplifting, and they combine successfully with almost all other groups. Citrus oils pair well with Florals, like lavender or geranium, and they also harmonize with deep, grounding Woody oils like cedarwood. This wide compatibility is useful for beginners, as a Citrus note can often lighten a heavier blend.
Woody oils, including sandalwood and pine, serve as a grounding foundation and blend with nearly every other category. Their warm nature allows them to temper brighter, more volatile scents or deepen delicate Floral compositions. Spicy oils, such as clove or cinnamon, are potent and warm, finding their aromatic matches in Florals and Citrus oils, though they must be used sparingly.
Herbaceous oils like rosemary or clary sage, with their fresh, green aromas, typically blend well with the Woody and Minty families. Resinous oils, such as frankincense or myrrh, are deep and long-lasting, providing an anchoring element that frequently complements Citrus and Floral scents. Selecting oils from two or three compatible families establishes an initial balance before refining the blend based on evaporation rate.
Understanding Aromatic Notes for Blending
Beyond scent families, successful blending relies on understanding aromatic notes, which refer to an oil’s volatility, or how quickly its molecules evaporate. This concept divides oils into three categories—Top, Middle, and Base notes—based on their molecular weight and evaporation rate. A balanced blend should contain oils from at least two, and ideally all three, categories to ensure the scent evolves and lasts over time.
Top notes consist of the smallest, lightest molecules and are the first scent perceived, creating the initial impression. These oils, often from the Citrus and Minty families, evaporate the fastest, typically within one to two hours. They provide an immediate burst of freshness but require heavier notes to prolong the overall aroma.
The Middle notes, sometimes called the “heart” of the blend, are medium-sized molecules that balance the mixture and form the core scent profile. These notes, which often include Florals and Herbaceous oils, are noticeable after the top notes fade and can last for two to four hours. They act as a bridge to the foundation.
Base notes are the largest, heaviest molecules and are the slowest to evaporate, sometimes lingering for several days. Oils in this category, such as those from the Woody and Resinous families, are considered “fixatives” because they ground the blend and slow the evaporation of lighter notes. For a well-rounded blend, aim for a ratio where Middle notes dominate (around 50%), followed by Top notes (around 30%), and Base notes (around 20%).
Practical Blending Ratios and Dilution
Once the desired aromatic combination is achieved, the next step is blending, which requires careful measurement and appropriate dilution for topical use. Essential oils are highly concentrated chemical compounds, and they must always be diluted in a carrier oil before being applied directly to the skin. Dilution is a safety measure to prevent skin irritation and sensitization, as the carrier oil slows the absorption and evaporation of the essential oils.
Standard dilution rates vary depending on the area of application and the age of the user, typically ranging from 0.5% to 3%. For delicate or sensitive areas, such as the face, or for use on children and the elderly, a 0.5% to 1% dilution is generally recommended. This means adding approximately 3 to 6 total drops of essential oil for every 30 milliliters (one ounce) of carrier oil.
For general body massage or application on healthy adult skin, a 2% to 3% dilution is the standard rate, which translates to about 12 to 18 total drops of essential oil per 30 milliliters of carrier oil. It is important to count the total drops of all essential oils used in the blend, not just drops per individual oil, to ensure the concentration remains within the safe range.
Appropriate carrier oils are non-volatile vegetable oils that mix well with essential oils. Popular choices include jojoba oil, sweet almond oil, and fractionated coconut oils. Blending should always be done in glass containers, as the potent chemical constituents in essential oils can degrade or react with plastic. Keeping a detailed record of the number of drops used for each oil is crucial for recreating a successful blend.