Fragrance is typically what drives the decision to make candles rather than buy them. Getting the scent right — strong enough to fill a room without overpowering it, consistent from pour to pour, stable through a full burn — involves understanding a handful of measurable variables rather than just following intuition.
This guide covers fragrance load limits, note structure in scent blending, flash points, and how fragrance oils and essential oils differ in practical candle-making terms.
Fragrance Oil vs. Essential Oil
These terms are sometimes used interchangeably, but they refer to different product categories with different properties in candle applications.
Fragrance Oils
Fragrance oils are synthetic or semi-synthetic aromatic compounds formulated specifically for use in candles, soaps, and diffusers. They are designed to be stable at candle-making temperatures and to bind reliably with common waxes. Most are formulated by fragrance houses to IFRA (International Fragrance Association) standards, which set usage limits for sensitizing compounds.
For candle applications, fragrance oils are generally the more predictable option: they have specified flash points, known fragrance load ceilings per wax type, and are engineered to throw well on cold and warm surfaces.
Essential Oils
Essential oils are steam-distilled or cold-pressed extracts from plant material. They contain the actual volatile compounds responsible for a plant's scent. In candle making, essential oils present several practical challenges:
- Many have low flash points — citrus oils (lemon, bergamot, orange) can flash at 45–55°C, close to or below many wax pour temperatures.
- They evaporate more readily than fragrance oils, which can mean the scent dissipates before the wax fully sets.
- They are generally more expensive per unit of scent impact than fragrance oils.
- Throw tends to be lighter, which some crafters prefer for subtler applications.
Essential oils work well in candles when used with waxes that have a lower pour temperature (such as coconut wax) and when the fragrance is added at the lowest appropriate temperature to reduce evaporation.
Fragrance Load: What the Percentage Means
Fragrance load is expressed as a percentage of the total wax weight. A 6% fragrance load in a 500g wax pour means 30g of fragrance is added. This is not the same as the volume of fragrance; weight is the correct measurement because fragrance oils have varying densities.
Example calculation: 500g soy wax at 8% fragrance load = 40g fragrance oil. If blending two scents, a 70/30 split gives 28g of the primary and 12g of the secondary, staying within the 40g total.
Why Exceeding the Load Limit Backfires
Each wax type has a maximum fragrance load it can bind chemically. Exceeding it does not produce a stronger scent throw — the unbound fragrance oil separates from the wax matrix. This manifests as oily pooling on the candle surface (called fragrance seep), a greasy feel on finished candles, and potential fire risk if the pooled oil ignites at a different temperature than the wax.
| Wax Type | Recommended Load Range | Maximum (supplier-specified) |
|---|---|---|
| Soy (container grade) | 6–8% | 10–12% |
| Coconut wax | 8–10% | 12% |
| Paraffin (container) | 8–10% | 12% |
| Beeswax | 3–5% | 6% |
Flash Points and Safety
The flash point of a fragrance oil is the temperature at which its vapours can ignite in the presence of a spark or flame. It is not the same as the combustion temperature of the liquid itself, but it matters for two reasons in candle making:
- Pour temperature: Fragrance should be added to wax below the fragrance oil's flash point. Most candle fragrance oils have flash points between 65°C and 93°C — well above standard pour temperatures. Some essential oils (particularly citrus) flash below 60°C and require careful temperature management.
- Storage: Fragrance oils with low flash points should be stored in sealed, cool, dark environments away from heat sources.
Suppliers in Canada are required to provide Safety Data Sheets (SDS) for fragrance oils, which include flash point data. Reviewing the SDS before working with a new fragrance is a practical precaution, not just a regulatory formality.
Note Structure in Fragrance Blending
Perfumery divides scent compounds into top, middle (heart), and base notes based on their evaporation rate. In a candle, this translates to the scent profile that emerges at different points during the burn:
Top Notes
Top notes are high-volatility compounds that evaporate quickly. In a burning candle, they are the first scent detected but fade soonest. Examples include citrus (bergamot, lemon, grapefruit), green herbs (eucalyptus, basil), and some light florals. Candles that rely heavily on top notes often smell bright initially but lose character as the burn continues.
Middle Notes
Middle notes form the body of the scent. They are slower to evaporate and persist through most of the burn. Lavender, rose, ylang-ylang, geranium, and most spice notes (clove, cinnamon at lower volatility) function as heart notes. A well-structured candle fragrance is anchored by its middle notes.
Base Notes
Base notes are low-volatility compounds that evaporate slowly and provide the lasting undertone of a fragrance. In candles, they become more prominent in the later stages of the burn. Common base notes include sandalwood, cedarwood, vetiver, vanilla, and musks. They also act as fixatives, slowing the evaporation of the more volatile top and middle notes.
Practical Blending Ratios
There is no single correct ratio, but a commonly used starting point for balanced candle blends is approximately 30% top notes, 50% middle notes, and 20% base notes by fragrance weight. Adjustments depend on the specific fragrance materials being combined and the wax's own scent characteristics (beeswax, for instance, contributes its own warm, honeyed base note).
Adding Fragrance: Temperature and Technique
Fragrance oils should be added to melted wax that has cooled below the wax's pour point but above the fragrance's minimum incorporation temperature. For most soy container waxes, this is typically in the 60–65°C range. Stirring should be slow and thorough — at least 2 minutes — to ensure even distribution throughout the wax.
Adding fragrance to wax that is too hot accelerates evaporation of volatile compounds and can affect the finished scent profile. Adding it to wax that is too cool risks incomplete binding, leading to fragrance separation.
References
- IFRA (International Fragrance Association) — ifrafragrance.org
- National Candle Association — candles.org
- Wikimedia Commons — Essential oil kit (CC)
