Burn behaviour
Candle tunnels down the centre
Tunnelling is the most common burn fault. The flame is consuming wax straight down without reaching the vessel wall, so half the candle is wasted by the time the wick drowns.
Written by Maya Holloway
Likely causes
- Wick is under-sized for the vessel diameter.
- First burn was cut short before the melt pool reached the wall.
- Wax has high melting point relative to the wick output.
- Draft pushing the flame off-centre during burn.
How to diagnose
- Measure the vessel inner diameter and compare to the wick chart.
- On a fresh burn, time how long it takes the melt pool to reach the wall. Anything over 2.5 hours suggests under-wicking.
- Inspect for a tilted wick or scorch marks on one side.
What to change next batch
- 01
Size up the wick one increment (e.g. ECO 8 → ECO 10) and retest.
- 02
Educate buyers: first burn must run at least 2 hours, preferably until the pool reaches the wall.
- 03
If the wax is dense (palm, paraffin pillar), check it is rated for containers, not pillars.
- 04
Move the candle away from drafts and trim the wick to 5 mm before every burn.
Related symptoms
- Wick drowns in the melt pool
Flame dies, wick goes under.
- Candle barely scents the room when lit
Cold throw is fine, hot throw is dead.
Read deeper
- Wick testing protocol: the 4-burn method
Wick testing is the difference between a candle that sells and a candle that smokes. Here's the 4-burn method.