TDS: What Is It and What Does It Tell You?
Every fragrance oil has an identity. The TDS (Technical Data Sheet) is its definitive profile — the manufacturer's written commitment telling you "this is how this raw material behaves." Starting a formula without reading it is like setting off on a journey without a map.
A TDS is not an analysis report. Do not confuse it with a COA (Certificate of Analysis). The TDS describes the product's general technical profile; the COA gives you the measured results for the specific lot in your hands. The TDS is fixed; the COA varies from batch to batch.
A typical TDS contains: a scent description, appearance, specific gravity (density), solubility profile, flash point, refractive index, IFRA compliance status, and recommended applications. Every line represents a decision in your formula.
Density: Grams or Millilitres?
The most frequently overlooked line on a TDS is specific gravity (density, g/ml). Many formulators think in millilitres, then find the bottle overflows — or is left half empty. There is one reason: failing to account for density.
Fragrance oils are not like water at 1.00 g/ml. Light, citrus-forward fragrance oils sit at around 0.84–0.90 g/ml; heavy resins and some synthetics can exceed 1.10 g/ml. The same 10 grams therefore occupies very different volumes.
For this reason, build your formula by weight (g) — weighing is far more reproducible than measuring by volume. If bottling is done volumetrically (ml), convert using the density figure.
| Ingredient type | Typical density (g/ml) | How many ml is 10 g? |
|---|---|---|
| Citrus fragrance oil (light) | ~0.85 | ~11.8 ml |
| Ethanol (perfumer's alcohol) | ~0.79 | ~12.7 ml |
| Floral/woody fragrance oil (medium) | ~0.95 | ~10.5 ml |
| Heavy resin / some synthetics | ~1.10 | ~9.1 ml |
The values in the table are typical ranges; the exact figure is always stated in the product's TDS. Read that first, then calculate.
Solubility: Clarity Is Not a Coincidence
The "solubility" line on a TDS tells you in which medium the fragrance oil remains clear. It typically reads "soluble in high-strength ethanol." Skip this line and your product will turn cloudy — looking "spoiled" to the customer.
The most common mistake: adding too much water to high-strength alcohol. Water disrupts the fragrance oil's solubility, resulting in haziness and phase separation (the liquid splitting into layers). There is no universal "add exactly this many grams of water" formula — every formulation has a different water tolerance.
The right approach: keep the water content low, start with very little, and test clarity visually. If clarity is struggling, use a ready-made perfumer's alcohol or the appropriate solvent recommended in the TDS.
- Weigh out the fragrance oil
Add your target quantity by weight. Keep the working sample small (50–100 g) to minimise the cost of any mistakes.
- Add high-strength alcohol
Add the appropriate alcohol according to the TDS solubility note and mix gently.
- Check for clarity
Hold the container up to a light source. If it is cloudy, do not add water; increase the alcohol proportion if needed.
- Add water drop by drop, if required
If you must add water, do so in tiny, incremental amounts. Check clarity again after each addition. Stop the moment you see haze.
- Prepare for cold filtration
After maceration you will chill and filter the blend (see the next section). For now, simply aim for a clear starting solution.
Flash Point, Maceration and the IFRA Line
The last three critical lines on a TDS are often the least read yet the most important: flash point, recommended use, and IFRA status. These cover the safety and regulatory compliance side.
The flash point is the lowest temperature at which a liquid's vapour can ignite. In alcohol-based fragrances this value is low; it affects storage, labelling and — critically — shipping/transport classification. If you are a manufacturer or seller, take this line seriously: logistics regulations are determined by it.
The IFRA line can be misleading if read carelessly. IFRA limits are not based on the total fragrance oil concentration; they are set according to the individual ingredients and allergens within the fragrance oil and the product category (leave-on vs. rinse-off). There is no blanket rule such as "every fragrance oil is safe up to 20%." When you see an IFRA compliance statement on a TDS, read the fragrance oil's IFRA certificate / compliance declaration for the full detail.
A TDS may not include a dedicated "maceration" line, but the solubility and appearance notes will guide you. Maceration is more than simply waiting; the interaction — including esterification — between alcohol and fragrance oil allows the scent to settle and softens the harsh "alcohol spike." Maceration at room temperature (~15–20 °C), protection from light, and subsequent cold filtration (removing waxy deposits) all noticeably improve clarity and olfactory balance.
Reading the TDS Into Your Formula: The Longevity Fallacy and FAQs
The TDS gives you numbers; you turn them into decisions. The biggest trap here is the longevity expectation. Most people assume "if I increase the concentration, the scent lasts longer." That is not correct.
Longevity and sillage are not determined solely by fragrance oil concentration. The true driver is the volatility of the raw materials. A 25% extrait built around citrus can fade quickly; a 10% product dominated by amber, oud or musk may last far longer. Concentration classifications such as EDP and EDT do not determine performance on their own — the formula's structure and volatility profile do. Hour-range promises should never be made as absolutes; they must be tested on your own formula.
The table below translates each TDS line into "what it means for your formula":
| TDS line | Your formulation decision |
|---|---|
| Specific gravity (density) | Perform the g↔ml conversion; prevent overfilling or underfilling at bottling |
| Solubility profile | Choose the correct solvent; keep water content low and test for clarity |
| Flash point | Plan your storage, labelling and transport classification |
| IFRA compliance | Limit usage level according to product category; retain the declaration |
| Appearance / colour | Compare with the COA; use as a reference during lot verification |
You have now learned to read a TDS. The numbers are turning into decisions. The rest is your signature.
Are a TDS and a COA the same thing?
Why must I always account for the density stated in the TDS?
If the TDS says IFRA "compliant," can I use any concentration I like?
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