In short
A safety data sheet tells you what a material's hazards are and how to handle, store and dispose of it safely, and a CAS number tells you which substance it is. Before you open a new material, read sections 2, 4, 7 and 8 of its SDS, copy the key points into your records, and remember that neither document guarantees quality.
What you will learn
- Find the sections of an SDS that matter most at the bench
- Explain what a CAS number does and does not tell you
- Create a one-line material record from supplier documents
Before this lesson: What Are Aroma Chemicals? A First Guide
Where to get one
Reputable suppliers provide an SDS for what they sell, often on the product page. If a seller cannot give you one, treat that as a warning about the seller. The reference guide on the SDS and specifications explains how these documents differ from a certificate of analysis. What follows is how to read one for the first time.
The sections that matter at your bench
In the US, OSHA's Hazard Communication Standard sets a 16-section format, and the same order appears internationally under the GHS, though local requirements differ. You do not have to read every section with equal care at the start.
| Section | Title | What to look for | Priority |
|---|---|---|---|
| 1 | Identification | Product name, supplier, emergency contact | Copy it |
| 2 | Hazard identification | Pictograms, signal word, hazard statements | Read first |
| 3 | Composition | CAS number, and hazardous components of a mixture | Copy it |
| 4 | First-aid measures | What to do after skin or eye contact | Read before opening |
| 5 | Fire-fighting measures | Flammability and how to respond | Skim |
| 6 | Accidental release | How to clean up a spill | Skim |
| 7 | Handling and storage | Conditions, and what to keep it away from | Read |
| 8 | Exposure controls and PPE | Ventilation, gloves, eye protection | Read |
| 9 | Physical and chemical properties | Appearance, flash point, density | Copy flash point and density |
| 10 | Stability and reactivity | What it reacts with, how it degrades | Skim |
| 11 to 12 | Toxicological and ecological information | Health and environmental data | Later |
| 13 | Disposal | How to get rid of it | Read when disposing |
| 14 to 16 | Transport, regulatory, other | Shipping classes, rules, revision date | Note the revision date |
Reading the hazard statements
Section 2 contains short, standard phrases such as may cause an allergic skin reaction or flammable liquid and vapor. Take them at face value. They describe the material as supplied, usually neat, and they are not about how it would behave in a finished perfume. An SDS is about handling the substance. It does not tell you how much is safe to use on skin, which is a separate question that Level 10 addresses through IFRA Standards and safety assessment.
What a CAS number does
A CAS Registry Number identifies a chemical substance across names and languages, which makes it very useful for cutting through trade names. Know its limits, though:
- It does not tell you about quality, purity or odor.
- Natural materials may have a number for the extract of a species, which covers a wide range of actual compositions.
- One material can have more than one CAS number, depending on how it is described, and a number on a label can occasionally be wrong.
You can compare a number against an independent record such as the one linked on each page of the material encyclopedia. The guide on material names and CAS numbers explains how names and numbers relate.
What these documents leave out
An SDS will not tell you how a material smells, whether this lot is good, or how much you may use in a perfume. For a lot's actual quality you would need a certificate of analysis, and for an odor judgment you need your own nose.
Practical exercise: Read one real SDS
Choose one material you own or plan to buy, and download its SDS from the supplier. A common oil such as lavender or lemon is a good first example.
- Read sections 2, 4, 7 and 8. Write down anything you did not understand and look it up.
- Fill in one record with these fields: name on the label, supplier, lot number if you have it, CAS number, hazard statements, gloves or ventilation advice, storage advice, flash point, SDS revision date.
- Check the CAS number against its entry in the material encyclopedia, if the material is listed.
- Write down one thing you will now do differently when you handle it.
- Save the SDS in a folder you can reach quickly, on paper or on your phone.
You have done this well if you can find the hazards, first aid and storage sections without searching, you have noted the revision date, and you named one concrete change to how you handle this material.
Common mistakes
- Filing it without reading it. The moment to read an SDS is before you open the bottle, not after a spill.
- Reading an SDS as a usage limit. It is about handling. Skin safety limits come from other sources.
- Assuming natural materials have no hazards. Their SDSs often list several.
- Keeping an old version. Sheets are revised, so note the date and check again occasionally.
Safety
This lesson teaches you how to read a document. It does not assess any material or make your setup safe. If a hazard statement concerns you, choose a different material. If you are exposed and feel unwell, follow the sheet's first-aid section and seek medical help.
Key terms
- SDS
- Safety data sheet: a supplier's standardized document on a substance's hazards and how to handle it.
- CAS number
- A registry number that identifies a chemical substance. It identifies the substance, not its quality or grade.
- GHS
- The Globally Harmonized System for classifying and labeling chemical hazards, whose pictograms and hazard statements appear on labels and SDSs.
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.