In short
The carrier changes how a fragrance is released. Alcohol evaporates fast and carries volatile materials up with it. A fixed oil stays behind, holds fragrance materials and softens the opening. Water-based systems need solubilizers and behave differently again. So a formula rarely transfers unchanged. When you change the carrier, you should test and often rebalance it.
What you will learn
- Explain how carriers change evaporation and the opening
- Compare a concentrate in two carriers
- Decide what to change when you change a carrier
Before this lesson: Interpreting a Failed Stability Test
How common carriers compare
| Carrier | Opening | Later | Watch for |
|---|---|---|---|
| Ethanol | Bright, quick, diffusive | Clear progression | Flammable; shipping; some people avoid it |
| Fixed oils, such as caprylic/capric triglyceride | Softer, closer | Often closer to the skin | Solubility; oxidation of the oil; greasy feel |
| Esters, such as isopropyl myristate | Soft | Clean feel, little odor | Solubility; regulatory status varies by use |
| Water with solubilizer | Often muted | Short | Haze; preservation; see the solubilizing guide |
The reference guide on alcohol-free perfume covers formats and formulation. The Journal's perfume oil versus spray covers the same ground for wearers.
Why it happens
A material's escape depends on its surroundings as well as on its pure vapor pressure. In a fixed oil, a non-polar material is held comfortably and leaves more slowly than it would from a strip after alcohol has flashed off. Alcohol's own evaporation also assists the early release of volatile components. In a water-based system, the fragrance sits largely in micelles of solubilizer, and it has to get out of them. This is the same idea behind the partitioning lesson in the functional fragrance track.
What to rebalance
- Top lines may need to rise in an oil, since the opening is more muted.
- Heavy lines may seem stronger relative to the rest, so check the base.
- Solids and waxes that dissolved in alcohol may not dissolve here.
- Concentration may differ. You may need a different strength for a similar impression.
A note on comparing fairly
Paper absorbs oils and solvents differently, and a strip wet with oil stays wet. That can make a comparison misleading. Test on two substrates if you can, such as paper and cotton, and allow for the fact that neither is skin. Also make sure the concentrate and the percentage are the same when you compare carriers. The carrier also changes what the product is for regulatory purposes, so its IFRA category and label may differ.
Practical exercise: One concentrate, two carriers
- Choose a composition with a clear opening.
- Make the same strength in perfumer's alcohol and in a low-odor cosmetic oil or ester. Note whether each dissolves clearly.
- Apply equal weights to paper and to cotton. Let them settle.
- Compare at 5 and 30 minutes, then 2, 6 and 24 hours, coded if you can.
- Write what changed, and what you would rebalance. Make one change, and retest in the oil.
You have done this well if your comparison shows the concentrate and dose were the same, and your change responds to something you actually observed. This stays off skin.
Common mistakes
- Assuming a straight swap. The balance usually shifts.
- Ignoring the oil's own smell and aging. Fixed oils can go rancid. Date them.
- Using water without a plan. Water needs solubilizing and preservation, which is a formulation of its own.
Key terms
- Carrier
- The liquid that carries the fragrance in a finished product, such as ethanol, a cosmetic oil or a water-based system.
Knowledge check
Written and reviewed by the RUŌOD Lab team. This is general education, not legal, regulatory, medical or safety advice. Example dilutions and exercises are for learning, are not validated products, and have not been safety-assessed. Completing a lesson confers no qualification. How we check these lessons.