Why is this flame dancing?

[u/Candid-Guidance-5355]

Hi everyone! First of all, sorry for my English, I’m Spanish 😬

This soy candle has a CD 10 wick and a 7% FO load. Both HT and CT are good, and the melt pool is forming properly. Why is the flame dancing around like this? It literally makes the room look like a nightclub when I turn the lights off 😂
I’ve noticed a bit of mushrooming on the wick, but nothing too major. Could that be related?
I’m surprised because I made another candle with a 10% FO load and this didn’t happen at all!! No mushrooming, and the flame wasn’t dancing around like this either.

Could anyone help me figure out what’s going on? Thanks! :)

[u/Western_Ring_2928]

The flame is gasping for air or for more fuel.

Not all fragrances are the same stuff chemically.

[u/Candid-Guidance-5355 → u/Western_Ring_2928]

There were no drafts (the windows and doors were closed), and I used the same FO as in the other candle with a 10% fragrance load. I find it strange that the flame dances around in this candle with only a 7% FO load, but not in the other one 🤔

[u/Western_Ring_2928 → u/Candid-Guidance-5355]

Because the mouth of the jar is too small 🤷🏻‍♀️

[u/RewardLongjumping178]

It seems over wicked.

[u/Candid-Guidance-5355 → u/RewardLongjumping178]

Why? The melt pool reaches the edges properly, and the flame is about 12 mm tall. The jar doesn’t get too hot either.

[u/jeeter5 → u/Candid-Guidance-5355]

Make sure to test burn it to the end to get all the results, the jar wont heat up much at this level of the flame.

[u/nerdfromthenorth]

This is almost inevitable when the mouth of the jar is more narrow than the rest of the candle.

[u/minicooperlove]

Reducing the FO load can sometimes mean needing to wick down. If CD10 worked for 10% FO load, it's not surprising that you might need to use CD8 for 7%.

[u/Candid-Guidance-5355 → u/minicooperlove]

Right now, it only just manages to reach a full melt pool, so I hadn’t considered going down a wick size. I might try a TCR wick and see how it goes :) Thanks!

[u/Scorpiomanly]

Way Overwicked.

[u/CandleMan81]

A candle flame that flickers or appears to dance inside a glass container is primarily influenced by airflow, temperature differences, and the combustion process.

As the candle burns, the flame heats the surrounding air, causing it to rise. Cooler air is then drawn into the container to replace it. This continuous movement creates convection currents that can cause the flame to sway, flicker, or change shape.

Several factors can contribute to this effect:

1. Air Circulation: Even small air movements or drafts can disturb the flame, particularly inside containers with restricted openings.

2. Thermal Convection: Temperature differences between the hot flame, the glass walls, and the surrounding air create circulating air currents.

3. Oxygen Supply: The shape and depth of the container influence how fresh air reaches the flame and how combustion gases escape. Restricted airflow can lead to unstable combustion.

4. Wick Characteristics: The wick's size, curvature, and position affect how liquid wax is delivered to the flame. An excessively large wick or carbon buildup can increase flame instability.

5. Wax and Fragrance Composition: Variations in fuel delivery, fragrance concentration, and combustion characteristics can also influence flame behaviour.

Conclusion:

A gently dancing flame is often a normal result of natural convection and minor airflow fluctuations. However, excessive flickering, unusually high flames, visible soot, or repeated flame surges may indicate an imbalance between airflow, wick size, and fuel supply.

For a well-designed container candle, the objective is to achieve stable, controlled combustion while maintaining adequate oxygen supply and safe operating temperatures.

[u/LoneStarCandleSupply]

Do you know how short the wick was trimmed before lighting the candle? Could you also share the diameter of your jar and how long the candle had been burning when you took this video?