Practical Example Module 4:
Practical Example: Comparing Aroma Chemical Dilution in Different Solvents
Introduction: Why Dilution Matters in Perfumery?
Aroma chemicals are often too concentrated to be used directly in a fragrance formula. To make them manageable, they need to be diluted in a suitable solvent. The choice of solvent affects:
✔ Diffusion Rate: How quickly the scent spreads in the air.
✔ Longevity: How long the aroma lasts on the skin or blotter.
✔ Perception: Some solvents can modify the way a scent is experienced.
✔ Application Method: Whether the fragrance is a spray, roll-on, or solid perfume.
Step-by-Step: Making a 10% Dilution of an Aroma Chemical in Different Solvents
Materials Needed:
- 1 aroma chemical (e.g., Iso E Super, Vanillin, or Hedione)
- Ethanol (Perfumer’s Alcohol 95%)
- Fractionated Coconut Oil (MCT Oil)
- Precision Scale (0.01g accuracy)
- Glass Beakers or Bottles (10mL each)
- Pipettes or Droppers
- Fragrance Blotters (to test diffusion)
Step 1: Preparing the 10% Dilution
A 10% dilution means 10% aroma chemical + 90% solvent by weight.
🔹 Formula Calculation for 10mL (10g) Solution:
- 1g aroma chemical (e.g., Iso E Super)
- 9g solvent (either Ethanol or MCT Oil)
✔ Using a scale, weigh 1g of aroma chemical.
✔ For Ethanol Dilution: Add 9g of ethanol into a glass bottle and mix well.
✔ For Oil Dilution: Add 9g of MCT oil into another glass bottle and mix.
🚨 Tip: Gently shake or stir to ensure complete mixing. Some materials may take longer to dissolve in oil than in alcohol.
Step 2: Comparing Diffusion Rates on Blotters
Once the 10% solutions are ready, we will test them on scent blotters.
Method:
✔ Dip two blotters into each dilution (one for ethanol, one for oil).
✔ Allow to air dry for 30 seconds.
✔ Smell each blotter at 1-minute, 15-minute, 1-hour, and 4-hour intervals.
✔ Observe how quickly the scent evaporates and changes over time.
Step 3: Observing the Differences
| Property | Ethanol Dilution | Oil Dilution (MCT Oil) |
|---|---|---|
| Initial Scent Strength | Strong burst, very noticeable | Softer, more rounded |
| Diffusion Speed | Fast, projects quickly into the air | Slow, stays close to the skin |
| Longevity on Blotter | Fades within 2-4 hours | Lasts 8+ hours |
| Texture/Feel on Skin | Light, dries fast | Moisturizing, slightly oily |
| Best for | Sprays, Eau de Parfum, Eau de Toilette | Roll-ons, solid perfumes, body oils |
Final Conclusion: How Solvents Impact Perfumery
1️⃣ Ethanol allows rapid diffusion, making it ideal for sprays where immediate projection is needed.
2️⃣ Oil slows down diffusion, helping the scent last longer but with less projection.
3️⃣ Oil-based perfumes are more intimate, while alcohol-based perfumes project further into the air.
4️⃣ For long-lasting, moisturizing perfumes, use oil-based dilutions.
5️⃣ For strong sillage and projection, use ethanol-based dilution.
💡 Next Step: Try diluting other aroma chemicals (e.g., Ambroxan, Hedione, or Vanillin) in different solvents and compare their diffusion and longevity! 🔬👃