The Principle: Efficacy First, Fragrance Second
In a hand sanitiser, the real work is done by the ethanol concentration. Under the widely adopted WHO framework, the finished product targets ≥70% ethanol for effective antiseptic action. Fragrance is not the lead performer here — it is a subtle supporting note on the stage.
That is why the fragrance oil level is kept low: a barely visible signature, a trace that does not overwhelm the nose. Once the top notes have evaporated, the clean, sharp alcohol note of the sanitiser remains — and your job is to soften that sharpness.
Raw Material Table
The reference formula below is designed to maintain a finished ethanol concentration above 70%. The fragrance oil level is deliberately low.
| Raw Material | CAS No | Ratio | For 100 mL |
|---|---|---|---|
| Ethyl alcohol (96%) | 64-17-5 | 80% | 80 mL |
| Glycerin | 56-81-5 | 1.5% | 1.5 mL |
| Fragrance oil | — | 0.2% | 0.2 mL |
| Deionised water | 7732-18-5 | 18.3% | 18.3 mL |
Important: when you use 96% ethanol at 80% by volume, the actual ethanol in the finished product is approximately 77% (0.80 × 0.96). This falls within the effective range. If you increase the water proportion, the final ethanol concentration drops — do not go below the 70% threshold. Glycerin acts here as a skin emollient; do not exceed 2%, as higher levels will leave a sticky feel on the skin.
When selecting a fragrance oil, favour types that have low hydrophobic (water-insoluble) components and dissolve clearly in alcohol. Citrus-forward fragrance oils feel fresh and bright but are highly volatile — no significant trail is to be expected. This logic is similar to the low-level freshness sought in Cologne and Body Spray formulas.
Preparation Steps
Order matters. Pre-dissolving the oil phase (fragrance oil) in the alcohol is the key to maintaining clarity when water is added later.
- Pre-dissolution
In a glass or alcohol-resistant vessel, add the fragrance oil to the full quantity of ethanol and stir until a clear solution is obtained. This is the moment at which the fragrance oil dissolves most effectively on its own in the alcohol.
- Emollient addition
Add the glycerin and stir until homogeneous. Glycerin is highly water-soluble; a slight increase in viscosity at this stage is normal.
- Add water slowly
Add the deionised water gradually, with continuous stirring. As water is incorporated, the solution may turn cloudy (louching); this occurs when the hydrophobic components of the fragrance oil lose solubility and precipitate as micro-droplets. Monitor clarity visually throughout.
- Resting (maceration)
Leave the sealed mixture to rest at room temperature (~15–20 °C) in the dark for 24–48 hours. Maturation reactions slow as temperature decreases, so do not refrigerate at this stage.
- Chilling and filtration (if required)
If turbidity or sediment persists after maceration, chill the product at ~0–4 °C for approximately 24 hours, then pass it through cold filtration. Insoluble matter is removed and the bottle bottom stays clear.
Safety, Regulations, and Troubleshooting
A hand sanitiser comes into direct contact with skin, and therefore demands care both in terms of production safety and legal classification.
Flammability: High-strength ethanol has a low flash point and is highly flammable. Avoid static electricity, ensure good ventilation in the work area, and keep away from open flames and sparks. Use appropriate personal protective equipment (gloves, eye protection).
Category distinction: Because the product contacts skin, it is assessed under IFRA in line with the leave-on (approx. Cat. 4) logic; it is not the same as an ambient/room spray (Cat. 10A). The IFRA limit applies not to the total fragrance oil percentage but to individual substances/allergens within the fragrance oil and to the product category. Do not generalise with statements such as "any fragrance oil is safe up to this level" — always read the fragrance oil's IFRA compliance statement.
Regulations — a critical distinction: Products marketed with claims such as "kills germs/disinfects" are generally classified in Turkey as biocidal products and are subject to a different authorisation regime from cosmetics. The obligations for a cosmetic product positioned as "hand care/cleansing" differ from those of a biocidal product making antiseptic claims. Keep the procedural side (notification/authorisation steps) separate from the liability side (manufacturer/responsible person obligations); consult the relevant authority (TİTCK / ÇŞİDB biocidal legislation) for current procedures and fees. Bear in mind that notification/registration processes may be subject to official fees.
| Symptom | Probable Cause | Solution |
|---|---|---|
| Cloudiness (louching) | Water level too high; hydrophobic components of the fragrance oil have lost solubility | Reduce water proportion; pre-dissolve fragrance oil in alcohol first; apply cold filtration if needed |
| Sediment/precipitate at the bottle bottom | Waxy or heavy components settling after maceration | Chill at 0–4 °C for 24 hours + cold filtration; reduce fragrance oil to a lower level |
| Scent too weak / fades quickly | Low fragrance oil level + highly volatile structure (e.g. citrus); ethanol evaporates rapidly | Increase level to up to 0.3% (do not exceed the limit); choose a less volatile, more balanced accord |
| Yellowing / colour change | Light and oxidation; some aroma chemicals darken over time | Store in the dark; use amber/dark bottles; consider a trace amount of antioxidant (BHT/tocopherol) |
| Dryness/irritation on skin | High ethanol + insufficient emollient | Keep glycerin in the 1.5–2% range; a low-dose emollient addition restores balance |
| Sticky film on skin | Emollient (glycerin/MPG) level too high | Reduce emollient; keep glycerin below 2% |
Tips and Frequently Asked Questions
A correctly scented sanitiser gives users both confidence and a sense of freshness. The rest is your signature.
Keeping the fragrance oil level low is not just an aesthetic preference — it is a decision that affects efficacy, cost, and skin safety simultaneously. A clear, light, clean trace is the most elegant result in this product type. If you are after a more intense scent, look to alcohol-based fragrance (EDP/EDT) — that is where the ratio and longevity balance is built differently.
Will increasing the fragrance oil level make it last longer?
Would using a natural essential oil instead of a fragrance oil be safer?
Can I fragrance the product using a food/beverage flavouring?
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