The Chemistry of the Scent Throw
Candle making is a precise balance of wax, wick size, and 'fragrance load.' Adding too much fragrance oil (FO) can lead to 'sweeping' (where the oil leeches out of the wax) or poor combustion, while adding too little results in a candle with no 'scent throw' when lit.
Understanding Fragrance Load
Fragrance load is the percentage of fragrance oil relative to the weight of the wax.
- Standard Load: 6% to 8% is the industry standard for most soy and paraffin waxes.
- Maximum Load: Most high-quality soy waxes can hold up to 10% or 12% FO. Exceeding this limit will cause the oil to pool on top of the candle, creating a significant fire hazard.
The Density of Wax
Wax is lighter than water. One fluid ounce of water weighs one ounce, but one fluid ounce of melted wax weighs approximately 0.86 to 0.90 ounces. This calculator accounts for this density difference to ensure your weights are accurate.
The Formula
We calculate the total weight of the mixture required to fill your containers, then split that weight into its wax and fragrance components.
Wax Weight = (Total Volume * 0.86) / (1 + FO%)
Flash Points and Pour Temps
Beyond the weights, the temperature at which you add fragrance is critical. You must add the oil when the wax is hot enough for the molecules to bind (typically 185°F for soy), but not so hot that you exceed the 'Flash Point' of the fragrance oil, which would cause the scent to evaporate into the air before the candle even cools.