Guide
How to make candles smell stronger
A weak-smelling candle usually comes down to one of five things: fragrance oil added at too low a temperature or not stirred in long enough, too short a cure, a wick too small to build a full melt pool, the wrong fragrance load, or a wax that holds scent tightly. Add the oil at the temperature your wax supplier recommends and stir for about two minutes, cure soy candles for 1 to 2 weeks, and make sure the melt pool reaches the edge of the jar within 3 to 4 hours. Change one thing at a time so you know what made the difference.
Hot throw and cold throw
Candle makers describe scent strength in two ways.
- Cold throw is how strongly the candle smells unlit, in the jar. It's what a customer notices first.
- Hot throw is how strongly it scents a room while burning. CandleScience suggests judging it after two to four hours of burning.
A candle can have a good cold throw and a poor hot throw. That pattern points to the burn, such as the cure, wick or melt pool, rather than the amount of oil.
Diagnose the problem
| What you notice | Likely cause | Try |
|---|---|---|
| Smells strong cold, weak when lit | Not cured long enough, or small melt pool | Cure longer; check the wick |
| Weak both cold and lit | Too little oil, or oil not bound into the wax | Check load, mixing temperature and stirring |
| Oily or wet surface | More oil than the wax can hold | Lower the fragrance load |
| Melt pool doesn't reach the edge | Wick too small | Next wick size up |
| Fine in a small room, weak in a large one | Candle too small for the space | Wider jar or more wicks |
1. Use the right fragrance load
CandleScience recommends starting 1 to 2% below your wax's maximum, for example 8% in a wax rated to 10%. Northwood Candle & Craft notes that many strong fragrances perform well at 6 to 8%. Going past the wax's maximum doesn't help: the extra oil can't bind, so it sweats onto the surface and can make the candle burn poorly, which weakens the hot throw.
If you're well below the maximum and the candle is weak both cold and lit, raise the load by 1 to 2% in your next test. See how much fragrance oil to add for amounts per pound and typical maximums by wax.
2. Add the oil hot enough, and stir
Fragrance oil binds best when it's added to wax at the temperature your wax supplier recommends. CandleScience suggests 185°F (85°C), or up to 190°F for denser oils. Some coconut blends call for higher temperatures, and some soy waxes shouldn't be heated above 185°F, so the wax's data sheet is the figure to follow. Adding oil to wax that's too cool is a common cause of weak throw.
Stir gently for about two minutes after adding the oil, then stir again just before pouring.
Don't let a fragrance oil's flash point stop you from adding it at the recommended temperature. Northwood explains that flash points matter mainly for shipping and transport, not for mixing into wax.
3. Weigh everything
Fragrance load is a percentage by weight. Measuring oil in fluid ounces or with a measuring cup can leave you well short of the load you planned, because oils vary in density. Weigh both the wax and the oil on a scale.
4. Let the candle cure
Scent throw usually keeps improving for days or weeks after pouring. Soy and coconut blends typically need 1 to 2 weeks, and paraffin a few days. A soy candle burned the day after pouring will often smell far weaker than the same candle two weeks later. See how long to cure candles for typical times by wax.
5. Get a full melt pool
Most of a candle's scent is released from the melted wax, so a bigger melt pool means a stronger hot throw. If the melt pool doesn't reach the edge of the jar within 3 to 4 hours, the wick is probably too small. Go up a size and test again. Recheck the wick whenever you change the fragrance, the load or the dye. See how to choose the right wick size and why candles tunnel.
6. Consider the wax
Paraffin and paraffin blends usually give the strongest hot throw with the least oil. Coconut blends are also known for a strong throw. Soy can smell good, but it often takes more testing and a well-chosen wick to get there. If you've worked through everything else and a soy candle is still weak, a blend may be worth testing. See soy vs coconut vs paraffin vs beeswax.
7. Check the fragrance itself
Some fragrance oils are simply stronger than others at the same load. Essential oils usually give a weaker throw than fragrance oils made for candles. Each oil's IFRA certificate also lists the maximum level it can be used at in candles, which can be lower than your wax's limit.
8. Match the candle to the room
A small candle can't scent a large, open room, however well it's made. Wider containers create larger melt pools and a stronger throw, and wide jars often need two or three wicks. High ceilings, drafts and open windows all spread the scent more thinly.
How to test scent throw fairly
- Cure the test candles for the full cure time of your wax.
- Burn each one in a closed room, roughly the size of the room your customers will use it in, for 2 to 4 hours.
- Leave the room for a few minutes and judge the scent when you walk back in. Your nose gets used to a scent quickly.
- Ask other people too. Sense of smell varies between people and can change day to day.
- Change only one thing between tests, such as the load, the wick or the cure time, and write down the results.
Frequently asked questions
Why does my candle smell strong in the jar but not when lit?
A good cold throw with a weak hot throw usually points to the burn rather than the amount of oil. The candle may not have cured long enough, or the wick may be too small to build a full melt pool. Cure soy candles for 1 to 2 weeks and check that the melt pool reaches the edge within 3 to 4 hours.
Does adding more fragrance oil make a candle smell stronger?
Only up to the wax's maximum. Beyond that the oil can't bind with the wax, so it sweats out and can make the candle burn poorly. CandleScience recommends starting 1 to 2% below the maximum, for example 8% in a wax rated to 10%.
What temperature should I add fragrance oil to wax?
Use the temperature on your wax's data sheet. CandleScience suggests 185°F (85°C), or up to 190°F for denser oils. Some coconut blends are mixed hotter, and some soy waxes shouldn't go above 185°F. Stir for about two minutes after adding the oil.
Do soy candles smell weaker than paraffin candles?
Often, yes. Paraffin usually gives a stronger hot throw with less oil. Soy candles can still smell strong with the right fragrance load, mixing temperature, wick and a full 1 to 2 week cure, but they tend to need more testing.
Testing a new load? The wax & fragrance calculator works out the oil for any load and warns you when it goes above your wax's typical maximum.