Product Knowledge
Essential Oil Blending: Top, Middle, and Base Note Architecture
Essential Oil Blending: Top, Middle, and Base Note Architecture
Commercial fragrance development is structural engineering with molecules. Whether you are formulating a candle line, a skincare range, or a household product, understanding note architecture determines whether your product smells balanced at minute one and at hour six. This guide gives B2B buyers and product developers the technical framework for evaluating blends and communicating specifications to suppliers.
The Note Pyramid Explained
The fragrance pyramid organizes aromatic materials by volatility — how quickly they evaporate at room temperature.
Top notes evaporate within 15-30 minutes of application. They create the first impression and are typically small, light molecules: monoterpenes and aldehydes.
- Examples: Sweet orange (limonene, 90%+), lemon (citral 3-5%), bergamot (linalyl acetate), eucalyptus (1,8-cineole), peppermint (menthol)
- Molecular weight range: 136-154 g/mol (monoterpenes)
- Vapor pressure: >0.1 mmHg at 25 degrees C
Middle (heart) notes emerge as top notes fade and persist for 2-4 hours. They form the character of the blend.
- Examples: Lavender (linalool 25-45%, linalyl acetate 25-46%), geranium (citronellol, geraniol), rosemary (camphor, cineole), chamomile (chamazulene), clary sage (linalyl acetate 56-78%)
- Molecular weight range: 154-222 g/mol (oxygenated monoterpenes, sesquiterpenes)
- Vapor pressure: 0.01-0.1 mmHg at 25 degrees C
Base notes have the lowest volatility, lasting 6-24+ hours. They anchor the blend and provide depth.
- Examples: Sandalwood (santalol 90%+), vetiver (vetiverols, vetivones), patchouli (patchoulol 25-40%), cedarwood (cedrol 15-30%), frankincense (incensole, boswellic acids), myrrh
- Molecular weight range: 220-450+ g/mol (sesquiterpenes, diterpenes)
- Vapor pressure: <0.01 mmHg at 25 degrees C
Standard Blending Ratios for Commercial Products
The classic starting ratio taught in perfumery is 30:50:20 (top:middle:base) by volume. In practice, commercial formulations vary by product category:
| Product Category | Top | Middle | Base | Typical EO Load |
|---|---|---|---|---|
| Fine fragrance (EDP) | 15-25% | 30-40% | 35-50% | 15-20% in alcohol |
| Scented candles | 30-40% | 35-45% | 20-30% | 6-10% wax weight |
| Soap / body wash | 35-45% | 35-40% | 15-25% | 1-3% product weight |
| Room diffusers | 25-35% | 35-45% | 25-35% | 20-30% in DPG base |
| Skincare (leave-on) | 20-30% | 40-50% | 20-30% | 0.5-2% product weight |
These are starting frameworks. A reed diffuser, for instance, benefits from a higher base-note proportion because the slow evaporation medium (DPG or isopropyl myristate) already suppresses top-note projection.
Evaporation Rate and Fixation
A common formulation challenge: top notes vanish too quickly in the final product. Solutions include:
- Natural fixation: Adding 5-15% base-note material (vetiver, benzoin, or labdanum) slows overall evaporation through molecular interaction.
- Carrier selection: In candles, soy wax (melting point 49-60 degrees C) retains and releases fragrance differently than paraffin (MP 52-68 degrees C). Test at both cold throw and hot throw.
- Encapsulation: For laundry and cleaning products, microencapsulation extends top-note perception by 4-8 hours. This is a processing decision, not a blending one.
Practical Blending Workflow for Product Development
- Define the brief. Target emotion, product matrix, regulatory market (EU, US, China), and cost ceiling per kg of finished product.
- Select 2-3 materials per tier. Start with no more than 7-9 total components. Complexity beyond 12-15 materials at this stage creates analytical noise.
- Blend at 10x concentration in a neutral carrier (jojoba for skin, DPG for ambient) and evaluate at 30 minutes, 2 hours, and 8 hours.
- Iterate ratios in 5% increments. Document every trial with batch codes. A GC-MS reference of the final blend protects against supplier substitution later.
- Stability test. Accelerated aging at 45 degrees C for 4 weeks approximates 12 months shelf life. Check for odor shift, color change, and phase separation.
What to Specify When Ordering Blends from a Factory
When you commission a custom blend from a manufacturer like Aromiso, provide:
- Target application and regulatory market
- Maximum cost per kg of blend
- Restricted substances list (IFRA, EU Annex III, or your internal blacklist)
- Reference sample or GC-MS profile if replicating an existing scent
- Minimum order quantity expectations (custom blends typically start at 25-50 kg)
A clear brief reduces sampling rounds from 4-5 down to 2-3, saving 3-6 weeks in your development timeline.
Contact aromiso.com for custom blending services and formulation support.
