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.
Why this happens
Wax only vaporises where the flame's radiant heat reaches it. When wick output is too small for the vessel's cross-section, the melt pool never touches the wall. Every subsequent burn digs the tunnel deeper because the flame has less exposed wax to draw heat from.
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.
Change sheet · next batch
Fill in what you know. The change sheet below re-orders so the delta most likely to help your specific batch floats to the top.
Widen the melt pool to reach the wall in under 2 h.
Educate buyers so the memory ring forms at the wall, not mid-way.
Heavy loads cool the flame and shrink the pool.
Keeps flame height in spec so radiant heat stays consistent.
Take action
- 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.
- 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.