If you buy scented candles, you're probably seeing this mysterious note on the label more and more often:
UFI: XXXX-XXXX-XXXX-XXXX . Sounds scary? Yes, but…
What is the UFI number on a spark plug?
The UFI (Unique Formula Identifier) is a 16-character code assigned to a specific chemical mixture, such as the fragrance in a candle. Thanks to this code, if a sudden allergic reaction or poisoning ever occurs, a doctor or poison control center can check the exact composition of the mixture in seconds by entering this number into the system.
In the European Union, UFI is required for products that are classified as posing a health or physical hazard (e.g. certain chemicals, but also candles with specific fragrances).
So: UFI is not a "scare scare" , but proof that the manufacturer, despite having created a potentially dangerous product, took the issue seriously, reported the mixture to the system and took care of the formal safety aspect.
Safe fragrance concentration in a candle – how does Oyasumi do it?
You won't find UFI in our candles. Does this mean we don't care about our customers? Quite the opposite, our candles are produced only in safe concentrations, and there's no need for us to make these entries (they don't apply to us). For us at Oyasumi, something else is crucial: a safe fragrance concentration in an olive oil candle .
What does this mean in practice?
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Before it goes into a candle, each fragrance oil receives documentation from the supplier: safety data sheets (SDS), IFRA guidelines, and sometimes information on the CLP classification.
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On this basis, we calculate the maximum safe concentration in the candle, one at which the candle smells, but the mixture does not exceed the thresholds considered hazardous to health (e.g. it does not fall into higher hazard categories that would require more stringent labeling).
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We often go below the maximum permissible level to have an extra "safety margin" - especially in candles that you burn in small, poorly ventilated rooms.
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We test the scent: after the candle has matured, for cold throw (how it smells cold), and hot throw (how it smells when burning).
If the scent is pleasant, does not sting the nose, does not cause a headache and the candle burns cleanly – only then does it receive the green light.
We don't make candles "too strong." We make candles that are: safe , comfortable to use, and still pleasantly noticeable.
Paraffin, olive oil – can a candle be harmful?
The UFI number itself is just the tip of the iceberg. Every candle—whether paraffin, soy, or olive—produces combustion products during burning: soot, volatile organic compounds (VOCs), and particulate matter. This is normal when burning anything. However, the devil is in the details.
Paraffin candles
Paraffin candles are still very popular because paraffin is cheap and easy to work with. However, studies have shown that paraffin candles can emit gasoline, toluene, formaldehyde, and other irritating compounds , especially when burned for long periods, with poor-quality wicks, or in poorly ventilated rooms. The same applies to soy candles, which are actually a mixture of paraffin and soy.
Why do we choose olive wax?
At Oyasumi, we make candles from olive wax , without added paraffin. For you, this means you're choosing a candle without fossil fuels in its wax composition, it has a cleaner burn profile than paraffin (with the right wick and proper use), and with the right fragrance concentration and regular wick trimming, soot and smoke are minimal.
This doesn't mean that an olive candle emits nothing—every burning candle emits something. The point is that emissions are as low as possible, thoroughly tested, and compliant with standards , and that the candle is used responsibly.
Why does the UFI number appear on the spark plug?
You will find the UFI number on the label if the fragrance composition in the candle is classified as posing a health or physical hazard (e.g. specific H warnings).
What does this mean? The manufacturer submits the mixture to the Poison Centers Notification (PCN) system . The database contains the exact composition, classification, and toxicological data. The UFI on the label is therefore the "key" to this information.
Is it safe?
Candles of unknown origin vs. Oyasumi candles
It's not about scaring everyone with every paraffin candle or UFI number. It's about making an informed choice .
A candle you should avoid usually has: a lack of clear ingredients, no CLP markings, no manufacturer information, a very intense, "chemical" scent, a low price yet a promise of a "mega-powerful" fragrance, no detailed manufacturer information (including email address and phone number), and no batch number. This information is legally required, and its absence should raise red flags.
The Oyasumi olive candle is: 100% olive wax , paraffin-free , the fragrance selected in a safe concentration , calculated on the basis of documentation, full documentation (IFRA, SDS, CLP), burning tests thanks to which the candle has a nice flame, does not smoke and does not "bite" the throat.
Finally, one important point: A safe candle is a combination of two elements: a responsible manufacturer and a responsible user.
At Oyasumi, we take care of: selecting the wax (olive, paraffin-free), calculating safe fragrance concentrations, and documentation.
You are responsible for burning candles responsibly, airing the room, trimming the wick, and not exceeding the recommended burning time. Also, remember to keep candles and waxes away from small children.
And then the candle can truly be what it should be: a pleasant ritual, not a reason for stress.
