In short
To smell a raw material properly, dip a labeled paper strip into a dilution of it, usually 10% in alcohol, let the solvent flash off for a few seconds, then take short, gentle sniffs with the strip just below your nose. Then come back to it at set times, because much of what a material tells you appears only later.
What you will learn
- Prepare and label a smelling strip correctly
- Explain why materials are normally smelled in dilution
- Record a material's character over time
Before this lesson: Olfactory Fatigue: How to Rest Your Nose
Why not just open the bottle?
Smelling from the bottle shows you the most volatile part, at an uncontrolled strength, mixed with whatever has collected in the neck. It teaches you little and fatigues you fast. A strip spreads the material out and lets it evolve, and you can compare one strip with another or come back to it tomorrow.
Perfumers commonly evaluate materials at 10% in alcohol. That figure is a convention, not a standard, and practitioners vary. Very powerful materials are often smelled at 1% or lower, because at 10% they are still overwhelming. You will make your own dilutions in the lesson on dilution basics. Until then, you can practice this method with finished fragrances and essential oil samples.
The method, step by step
- Label first. Write the material, dilution and time on the dry end of the strip. Use pencil if you can, as ink has a smell of its own.
- Dip about a centimeter, and do it the same way each time, so that your comparisons are fair. Use a clean pipette to spot the strip if the bottle's neck is narrow. Never dip the strip into your stock bottle, since paper fibers and other residues contaminate it.
- Wait a few seconds so that the alcohol can flash off. Smelling too soon gives you mainly solvent.
- Hold the strip just below your nose without touching it. Take two or three short sniffs.
- Move it away and think. Then write your words down before you smell it again, as your first impression fades quickly.
- Put it down safely, on a strip holder or with the wet end over the edge of a surface, away from others. Then return to it at set times.
What to pay attention to
| When | Ask yourself |
|---|---|
| First seconds | What hits first? Is it sharp, sweet, green or chemical? Is there solvent? |
| 5 to 30 minutes | What is the main character now? What family does it remind you of? |
| A few hours | Has it changed? Is anything new appearing as the rest fades? |
| Next day | Is anything left? What is the residue like? |
The time scale differs by material: some citrus oils have largely gone within hours, and some musks stay for days or weeks. That longer-term behavior is called tenacity, and our guide to tenacity on a blotter shows how to record it carefully.
From one strip to comparison
A single smell is hard to describe, but a difference is much easier. Smelling two strips one after the other forces you to notice what separates them. Once you have the method, you should do most of your study this way, and the method in how to learn perfume materials uses it for whole families.
Practical exercise: A full evaluation of one material
Choose one material or essential oil, ideally bergamot or something else that changes visibly. Use a 10% dilution if you have one. If you do not, use a fragrance sample and note that it is not a single material.
- Prepare and label a strip as described above, and write the time.
- Write three to five words at 1 minute, then at 15 minutes.
- Write again at 1 hour, 4 hours and the next day. It is fine to miss one.
- Add a sentence comparing the first impression with what remained.
- Look the material up in the material encyclopedia only after you have finished. Note where your words agree, and where they differ.
You have done this well if your words were written before you looked anything up, you took breaks between materials, and you recorded where you and the reference disagree without changing your original note.
Common mistakes
- Dipping strips in the stock bottle. You contaminate your material. Decant first, or use a clean pipette.
- Touching your nose with the strip. That transfers material to your skin and confuses every smell that follows.
- Reading the description first. You will smell what you were told to smell. Write first, then look it up.
- Keeping all the strips together. They contaminate each other and your nose. Keep them apart, and throw away old ones.
Safety
Keep raw materials away from your eyes, mouth and skin, and work with ventilation. Alcohol-based dilutions are flammable, so keep them away from flame. If a material irritates you, stop, get fresh air and check its safety data sheet.
Key terms
- Smelling strip
- A narrow strip of absorbent paper for evaluating a material or fragrance. Also called a blotter, mouillette or touche.
- Neat
- Undiluted. A neat material is at full strength, as supplied.
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.