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Candle Tunneling: Causes And Fixes
Tunneling usually means a small wick or a short first burn. Prevention, foil rescue and burn-test habits—step by step.
A deep well around the wick and untouched wax at the walls—classic tunneling. It wastes wax, weakens throw and looks unfinished. At Rufus Concept we split causes into production and use, then map prevention and rescue.
What Tunneling Is
The flame melts only the centre; the pool never reaches the vessel. Later burns deepen that “memory.” Separate it from a cooling sink hole: sink is a top dent; tunneling leaves tall side walls.
- Undersized / wrong wick
- Short first burn
- Off-centre wick
- Very cool room or drafts
Causes
Wrong wick: Too small for diameter. Wide jars may need dual wicks or a larger series. Wood wicks need their own tests.
Short first burn: A 20–30 minute “try” teaches the tunnel. Wait for a full melt pool (often 2–4 hours by size).
Cold room: Wax melts lazily. Extreme heat raises soot risk—balance matters.
Fragrance overload: Excess oil can weaken the flame—stay in recipe range.
| Sign | Likely cause | Fix |
|---|---|---|
| Narrow well | Small wick | Size up / dual |
| Wall wax remains | Short first burn | Full-pool rule |
| One-sided melt | Wick drift | Re-centre |
| Weak flame + oil | High load | Lower % |
How To Rescue A Tunneled Candle
- Foil wrap: Reflect heat inward with foil on the rim; burn carefully until sides soften. Never leave unattended.
- Gentle heat: In the atelier, careful heat can level the top—at home, avoid spills and keep distance.
- Top-up: For production sink holes; tunneling’s real fix is wick and education.
Stop It Next Time
Burn-test every vessel before series. Trim to 5–6 mm; clear carbon mushrooms. Print “wait for a full first melt” on care cards—half of complaints are use habits.
Soy lines get more tunneling reports because wick match is sensitive—not because soy is “bad.” Paraffin blends may open a wider pool but still need tests. Beeswax and stearic firm the set—update wick charts.
- Log three wick sizes per SKU.
- Keep off drafts.
- Light and trim dual wicks together.
Three Tips To Extend Life
Make wick care a habit. Straighten after extinguishing. Lock supplies and diameter on the recipe card. Molded “centre dips” are often sink holes; tunneling talk is mostly for containers. Gel needs its own wick–gel match.
Summary: tunneling is wrong wick plus short first burn. Diagnose, size correctly, educate, foil if needed. Three wick sizes in one jar with Rufus Concept materials usually closes the tunnel.
Production Vs Use Diagnosis
If customer photos show tall side walls and a thin wick, audit production wick choice. If walls melted before but a deep well returns with “I only burn 20 minutes,” it is use education. That split stops pointless wick stock swaps.
Insisting on one thin wick in a wide jar is the top production cause. Price dual wicks against the cost of returns and complaints.
Burn-Test Template
Pour three wick sizes in the same vessel. Mark melt-pool diameter every 30 minutes on first burn. Log soot and flame height. Lock the winner on the SKU card. With Rufus Concept wick series, this template usually closes tunneling tickets.
Bold the line “wait for a full first melt” online. Teach support the foil method with safety warnings—never suggest unattended burns.
For dual-wick SKUs, print “light both together, trim both together” on the care card; lighting one wick alone recreates an asymmetric tunnel.