From jar to wax weight
Candle makers buy wax by weight but fill containers by volume, so the first step of any batch is converting one into the other. Wax is lighter than water: most container waxes, whether soy, paraffin, coconut or blends, weigh about 0.86 times the same volume of water. Beeswax is denser, at about 0.96.
The calculation
- Volume to fill: container volume × number of containers × fill level. A 90% fill leaves room below the rim.
- Total weight to pour: volume × water weight × wax factor. One fluid ounce of water weighs about 1.04 oz, and 1 ml weighs 1 g.
- Split wax and fragrance: fragrance load is usually expressed as a share of the wax weight. With a load of 8%, wax = total ÷ 1.08 and fragrance = wax × 0.08.
Example
Six 8 fl oz jars, filled to 90%, with an 8% fragrance load:
- Total to pour: 6 × 8 × 0.9 × 1.04 × 0.86 = about 38.8 oz, or 1,099 g
- Wax: 35.9 oz, or 1,017 g
- Fragrance oil: 2.9 oz, or 81 g
- Per jar: about 6.5 oz
Choosing a fragrance load
- 6 to 10% is the usual range; 8% is a good starting point for soy wax.
- Each wax has a maximum, often 10 to 12%, given by the supplier. Above it, oil can sweat out of the candle and becomes a fire risk.
- More fragrance does not always mean a stronger scent: the wick, wax and curing time matter as much.
Tips for better candles
- Measure your jar by filling it with water and weighing the water; listed volumes are often to the brim.
- Add fragrance at the temperature your wax supplier recommends, often around 185 °F, and stir gently for two minutes.
- Pour at the recommended temperature and let candles cure, soy for one to two weeks, before burning.
- Choose the wick size for the jar diameter and test-burn one candle first.
- Never leave a burning candle unattended, and keep it away from drafts and anything flammable.