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How much fragrance oil does a candle really need
Fragrance load is the weight of fragrance oil compared with the weight of wax, shown as a percentage. If you use 400 grams of wax and 32 grams of fragrance oil, the load is 8 percent, because 32 is 8 percent of 400. This simple ratio controls scent strength, safety, and burn quality all at once. Too little fragrance gives a candle that smells lovely when cold but almost nothing when lit. Too much fragrance can make the candle smoke, sweat oil on the surface, burn unevenly, or even become unsafe, because fragrance oil is fuel. Getting the load right is therefore one of the most valuable skills in candle making, and it is pure arithmetic once you know the weights.
Most wax makers publish a maximum fragrance load, often around 10 percent for soy and paraffin and lower for beeswax, because beeswax already has its own strong scent and holds less added oil. Fragrance makers also publish limits for each oil, and the lower of the two limits always wins. A candle at 12 percent may smell stronger in the shop, but if the wax can only hold 10 percent, the extra oil has nowhere to go. It may pool on top, leak, or make the flame flare. This calculator works from your wax weight and your chosen load, and it warns you when the load passes the usual maximum for your wax, so you can adjust before you pour.
How to use the fragrance calculator
Weigh your wax in grams, not millilitres, because fragrance load is a weight ratio and wax changes volume as it melts. Enter the wax weight and the load percentage you want to try, then choose your wax type. The tool gives the fragrance oil weight in grams and the total candle weight. For example, 400 grams of soy wax at 8 percent needs 32 grams of fragrance oil, for a total of 432 grams. Weigh the fragrance oil on the same scale, in a separate container, and add it to the wax at the temperature your wax maker recommends, usually around 60 to 70 degrees Celsius for soy. Stir gently for about two minutes so the oil binds with the wax instead of sitting on top.
Start testing at 8 percent for most container candles, then move up or down in one percent steps. Scent strength when cold, called cold throw, is always stronger than scent when burning, called hot throw, so judge a candle by its hot throw after a full melt pool forms. Some fragrance oils are naturally light and need a higher load, while others are very strong and smell best at 6 percent. Keep notes on each oil, because the same load gives very different results with different fragrances. A vanilla oil at 8 percent may fill a room, while a light citrus oil at the same load may barely register.
Why more fragrance is not always better
Beginners often assume that doubling the fragrance doubles the scent, but candles do not work that way. Above the wax’s limit, extra oil does not bind, so it can sweat out of the finished candle as oily beads, make the surface sticky, or cause smoking and sooting when lit. High loads can also soften the wax, so the candle loses its shape in warm weather, and they can weaken the wick’s draw, which causes tunnelling. In the worst case, pooled fragrance oil near the flame can flare, which is a fire risk. A well-made candle at 8 percent that burns cleanly always beats a strong-smelling candle at 14 percent that smokes and sweats.
Fragrance, wax, and wick work together
Fragrance load changes how a candle burns, so test wick and fragrance together, not separately. A higher load usually needs a slightly larger wick, because the oil thickens the melted wax and slows its climb up the wick. If you raise the load and the candle starts tunnelling, try the next wick size up before blaming the fragrance. Dye has a similar effect in smaller amounts. This is why candle makers test one recipe fully, wick, wax, fragrance, and dye together, before changing anything. When you change fragrance oil brands, test again, even at the same percentage, because each oil has a different weight and burn character.
A safe testing routine
Make small test batches of about 200 grams of wax so that failed tests cost little. Label every candle with wax, fragrance name, load percentage, pour temperature, and date. Cure container candles for at least one to two weeks before judging scent, because fragrance binds with wax as it cools and sets, and a candle judged the next day will smell weaker than the same candle a week later. Burn test candles in a normal room, not a tiny closed space, and check for soot, mushrooming, and leftover wax. Never exceed your wax maker’s maximum load, never add fragrance oil to a lit candle, and never leave a burning candle unattended. Use the calculator to get the grams right every time, and let careful tests, not guesswork, decide your final recipe.
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