Category: Tips | Reading time: 9 minutes
Introduction
"How much fragrance to add to a candle?" – this is the number one question among candle makers. And the answer you hear most often is: "6-10%". But what does that actually mean? Why not 15%? Why does 8% smell better than 12%? And what does the fragrance oil concentration have to do with the pictograms on the label?
In this article, we will combine two worlds: craftsmanship (how concentration affects scent and burn) with chemistry and law (how concentration affects CLP classification). Because in the case of scented candles, these two worlds intersect – and a conscious manufacturer should understand both.
1. What is fragrance load?
Fragrance load is the percentage of fragrance oil in the total weight of the candle. If your candle weighs 200g and you added 16g of fragrance oil – you have an 8% fragrance load.
The formula is simple:
Concentration (%) = (weight of fragrance oil / total weight of candle) × 100
Examples:
| Wax weight | Fragrance oil weight | Candle weight | Concentration |
|---|---|---|---|
| 188g | 12g | 200g | 6% |
| 184g | 16g | 200g | 8% |
| 180g | 20g | 200g | 10% |
Important: Concentration is calculated from the weight of the ENTIRE candle (wax + fragrance oil), not just the wax. This is a common mistake – "10% of wax" is actually about 9.1% of the candle's weight.
2. Why more doesn't mean better
Intuition suggests: more fragrance oil = stronger scent. And up to a certain point, that's true. But once the optimal level is exceeded, problems begin:
Physical problem: candle sweating
Soy wax has a limited ability to absorb fragrance oil. The typical limit is 10-12% (depending on the specific wax). Exceeding this limit causes excess oil to separate on the surface of the candle – it "sweats." This looks like oily droplets on the wax. It's not dangerous, but it looks unprofessional and customers notice it.
Burning problem: sooting and unstable flame
Too much fragrance oil changes the physical properties of the wax blend – density, viscosity, evaporation rate. A wick that burned perfectly at 8% might soot, produce too high a flame, or behave unpredictably at 12%. You would need to re-select the wick.
Scent throw problem: the saturation paradox
At too high a concentration, the scent can become "flat" or unpleasant – individual notes blend together, the top note dominates, the base disappears. Paradoxically, a candle with 8% fragrance oil may smell better than one with 12%, because the proportions of the scent notes are more balanced.
Legal problem: classification threshold
And here we come to the core of what distinguishes our article from any other guide on the internet. Fragrance oil concentration directly determines your candle's CLP classification. More fragrance oil = higher concentration of hazardous substances in the candle = exceeding classification thresholds = pictograms, UFI, PCN, costs.
3. Concentration and CLP classification - the key link
This is the section you won't find in any other guide on fragrance load. And it should be the first.
Every fragrance oil contains substances that have classification thresholds – a concentration above which a mixture (your candle) becomes "hazardous" in the CLP sense. For example:
| Fragrance oil | Classification threshold | At 6% | At 8% | At 10% |
|---|---|---|---|---|
| Fragrance oil A (mild) | ~10% | Clean | Clean | Borderline |
| Fragrance oil B (typical) | ~5% | H317 + UFI | H317 + UFI | H317 + UFI |
| Fragrance oil C (delicate) | ~15% | Clean | Clean | Clean |
See? The same fragrance oil A at 8% is "clean" (zero formalities), but at 10% it enters the borderline zone. And fragrance oil B even at 6% requires full CLP documentation. This doesn't depend on the amount of fragrance oil in general – it depends on the composition of the specific fragrance oil × your concentration.
Therefore, the question "how much fragrance to add?" has two answers: one artisanal (how much is needed for a pleasant scent) and one legal (how much is allowed before you incur costly formalities). A wise manufacturer balances both.
4. Optimal Concentrations - A Practical Guide
6% - subtle scent, minimum formalities
Ideal for: oils with a low threshold (below 8%), customers preferring delicate scents, bedrooms, small rooms. With many oils, 6% keeps you below the classification threshold – zero pictograms, zero UFI. Maximum simplicity.
8% - the gold standard
The most commonly used concentration in the industry. Distinct scent, fills a room well, wax holds the oil effectively. For oils with a threshold above 8% – you are still in the "clean" zone. For oils with a threshold of 5-7% – you may already require classification.
10% - strong scent, full documentation
For strong character oils, large rooms, customers who like intense scents. For many oils, 10% exceeds the classification threshold – you need a full CLP label, UFI, and PCN notification. But you have a ready-made SDS from TopWosk – documentation is taken care of.
Above 10% - is it worth it?
Rarely. The scent gain is marginal (8→10% gives a noticeable difference, 10→12% almost none), and problems increase (wax sweating, sooting, worse scent profile). Plus: higher concentration = higher concentrations of hazardous substances = potentially additional CLP classifications beyond H317.
5. How to calculate how much fragrance oil you need
Weight method (recommended)
Always weigh the fragrance oil - do not measure by volume. Fragrance oils have different densities (from 0.9 to 1.1 g/ml), so 10ml of one oil weighs differently than 10ml of another.
Formula for fragrance oil weight:
Fragrance oil weight (g) = candle weight (g) × concentration (%)/100
Example: You want a 220g candle with 8% fragrance oil → 220 × 0.08 = 17.6g fragrance oil. You weigh out 17.6g of fragrance oil and 202.4g of wax.
Concentration calculator
| Candle weight | 6% fragrance oil | 8% fragrance oil | 10% fragrance oil |
|---|---|---|---|
| 100g | 6g | 8g | 10g |
| 150g | 9g | 12g | 15g |
| 200g | 12g | 16g | 20g |
| 250g | 15g | 20g | 25g |
| 300g | 18g | 24g | 30g |
Print this table and hang it above your workspace. It will save you from pulling out a calculator every time you pour.
6. Concentration Strategy - How to approach your offer
You have 20 scents in your offer. You don't have to make them all at the same concentration. Here's a strategy:
Step 1: Check classification thresholds
For each fragrance oil at TopWosk, we provide the classification threshold. Divide your fragrance oils into groups:
- Group A (threshold above 10%): You can use 6%, 8%, or 10% - all variants clean or max EUH208. Choose the concentration based on scent preference.
- Group B (threshold 5-10%): At 6%, probably clean. At 8-10%, they may require classification. Test: does 6% provide enough scent throw? If so - you save time and money.
- Group C (threshold below 5%): Even at 6% requires classification. You accept the formalities (you have a ready-made SDS from TopWosk) and adjust the concentration for the scent.
Step 2: Optimize for costs
Every fragrance with H317 classification incurs additional costs: CLP label, potentially UFI + PCN (€125 via Chemtra). If you have 20 fragrances and 15 of them fall below the threshold at 6% - you save 15 × €125 = €1875 on PCN notifications alone. It's worth calculating.
Step 3: Test scent intensity
For each group, perform a hot throw test: light a candle with 6% and one with 8%, compare after 2 hours of burning. Some oils give an excellent throw even at 6% - why pay more (financially and legally) for 8%?
7. Impact of wax on optimal fragrance load
Different waxes "hold" fragrance oil differently:
| Wax type | Typical max fragrance load | Optimal range |
|---|---|---|
| Soy wax (container) | 10-12% | 6-10% |
| Soy wax (pillar) | 8-10% | 6-8% |
| Soy-coconut blend | 10-12% | 6-10% |
| Paraffin wax | 10-15% | 6-10% |
| Beeswax | 6-8% | 4-6% |
Do not exceed the limit specified by the wax manufacturer - even if the CLP label allows for a higher concentration. The manufacturer's limit concerns physical safety (sweating, instability), while CLP concerns chemical safety. Both limits must be met.
8. Most frequently asked questions
"Can I add 15% fragrance oil to make it smell stronger?" - Technically, you can, but you shouldn't. Most soy waxes won't hold 15% - the wax will "sweat." The scent won't be twice as strong as at 8%. And the CLP classification will certainly be more restrictive. It's not worth it.
"6% seems too little - it doesn't smell" - Three possible reasons: too short a curing time (minimum 14 days!), improper wick (too small a melt pool = too little scent is released), or the fragrance oil has low intensity. Address each cause before increasing the concentration.
"What's the difference between % of wax and % of candle?" - If you calculate "10% of wax" - you take 100g of wax and add 10g of fragrance oil. The candle's weight = 110g. The concentration in the candle = 10/110 = 9.1%. The difference is small, but when calculating classification thresholds, it can be significant. At TopWosk, we provide thresholds as % of fragrance oil in the CANDLE (wax + fragrance oil).
"Does concentration affect burn time?" - Slightly. With a higher fragrance oil concentration, the wax melts slightly faster (fragrance oil lowers the melting temperature). The difference between 6% and 10% is about 5-10% shorter burn time - noticeable, but not dramatic.
"I have ready-made SDS for 6/8/10% - can I use 7%?" - Yes, but you don't have a ready-made SDS for 7%. Classification at 7% will be somewhere between 6% and 8% - if 6% is clean and 8% requires classification, then 7% may or may not require it. The safe option: treat 7% as 8% (use the SDS for 8%). Or stick to 6/8/10% - that's why we prepared them.
Summary
The concentration of fragrance oil in a candle is not just a matter of "how much it smells" - it's a decision that affects the candle's appearance, its burning behavior, documentation costs, and legal formalities. Key principles:
- 6-10% is the optimal range - above this, problems increase, and the scent does not increase proportionally.
- Concentration × fragrance oil composition = CLP classification - know your fragrance oil's classification threshold BEFORE choosing the concentration.
- There is no "one ideal concentration" - each fragrance oil, wax, and container requires testing.
- Weigh, do not measure by volume - the density of fragrance oils varies.
- Cure for a minimum of 14 days - before assessing whether the concentration is sufficient.
At TopWosk, for each fragrance oil, we provide the classification threshold and supply ready-made Safety Data Sheets at three concentrations: 6%, 8%, and 10%. You choose consciously - you know how much fragrance you can add and what the consequences will be. Check out our fragrance oils →