In short
To evaluate a new aroma chemical, read its documents first, then smell it diluted on a strip over time, then test it in simple accords, and finally write down what it does and at which dose. A beginner's material study asks what something smells like. This method goes further and asks what the material does and where its limits are. The Lab's guide to learning materials covers the earlier stage.
What you will learn
- Follow a repeatable protocol for an unknown material
- Describe a material's use in terms of effect
- Write a material card that can be used later
Before this lesson: Sustainable Ingredient Innovation
The protocol
Step 1: documents
Before opening the bottle, collect the SDS, specification, CAS number, any IFRA or other restriction, and whether it is sold neat or diluted. A material sold at 10% is a different weighing problem. If a seller can't provide an SDS, reconsider buying from them, as incoming checks explains.
Step 2: dilution and first smell
Make 10% and 1% solutions, and a 0.1% if you suspect it is strong. Smell the weakest first. Record your first impression without looking at the supplier's description. Then compare with what it says, and note where you differ.
Step 3: the time course
Dip two strips, label them, and smell them at 5 minutes, 1 hour, 4 hours, 24 hours, and then daily until nothing remains. Record it in a table, using the method from tenacity on blotter. Note any change in character as well as strength, because a material that changes as it dries can be a surprise inside a formula.
Step 4: neighbors
Smell it beside the two materials you think it most resembles. What does it do that they do not? If you can't find an answer, ask why you need it.
Step 5: effect in accords
Dose it into at least two simple accords of different character, at about three levels. Compare each with an undosed control, blind.
| Accord | Dose (%) | What changed | Too much at |
|---|---|---|---|
| Simple citrus | 0.1 / 0.5 / 2 | Your notes | Your notes |
| Simple floral | 0.1 / 0.5 / 2 | Your notes | Your notes |
Step 6: practical checks
- Does it dissolve cleanly in alcohol at the dose you expect? See dissolving solid aroma chemicals.
- Does it discolor in a small trial over weeks? Keep one sample in light and one in the dark.
- What does it cost at the dose you would use?
Step 7: the card
Write it to be useful in a year. It should cover identity and source, documents and their dates, odor in your own words, time course, what it does, the useful dose range you found in which contexts, the dose at which it became too much, its nearest alternatives, and any open questions.
Keep your evidence honest
A card says what you found, under your conditions, at that date, with that batch. Avoid "always", and mark observations by one person as just that. Do not write a safe use level from your own results: the card records character and handling only, and restrictions come from the proper sources.
Practical exercise: Write a full material card
- Choose one material you have never used.
- Follow all seven steps, and take the several days the time course requires.
- Show your card, without the name, to someone with a little perfumery experience. Can they understand what the material does?
- Use it in one small composition, and return to the card to correct it.
You have done this well if the card names a useful range and an excessive dose, separates your observations from the supplier's claims, and was corrected after real use.
Common mistakes
- Stopping at the description. "Woody, dry" doesn't tell you how to use it.
- Testing only one context. Context changes materials.
- Reading the sales copy first. It shapes what you smell.
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.