Your candle tunnels. You know the look: a neat hole down the center, a thick ring of unburned wax pressed against the glass, and by burn six the flame is a stubble that sputters. Everyone blames you. Burn it too short, they say. The real answer is in the first fifteen minutes, and it has nothing to do with you. It has everything to do with the jar.

The pool that never reached the wall

A candle only burns wax it has already melted into a liquid pool. That pool is fed by the flame, which conducts heat into the wax directly beneath it. Here is the number most people never hear: the pool grows until the heat the flame dumps in equals the heat the glass and the surrounding solid wax steal out. On a 7–8 cm diameter jar, that equilibrium pool is roughly the width of the jar minus a 2–3 cm solid rim. If your first burn never pushed the pool across that rim, the rim re-hardens into a wall. Every later burn melts against that same wall. You are not tunneling a candle. You are burning inside a tube someone cast for you.

We see it on the QC line weekly. The same wax, the same wick, the same jar. If the first burn is 15 minutes, the pool dies at 60% of the diameter and the rim freezes. If it is 80 minutes, the pool reaches the glass, the rim thins to a membrane, and the whole column becomes one burnable mass. Same product. Two different candles.

The 80-minute rule, and why the jar width sets it

The pool has to travel to the wall, and the wall has to soften. Glass is a slow conductor, and the wax next to it stays a few degrees under its melt point even when the center is liquid. Paraffin sits in a 46–68 °C window depending on blend, beeswax holds at 62–64 °C. That gap between the liquid center and the glass-edge rim is what takes time. For a typical 7–8 cm jar, that is 80–90 minutes of continuous burn. For a 10 cm jar it creeps toward two hours. That is the number to hit, once, on the first burn. After that the rim is gone and normal burn time is fine.

Wick size is the lever. A wick undersized for the diameter feeds too little heat, and no amount of patience reaches the wall. Our rule of thumb: wick diameter tracks roughly 1/16 inch per inch of jar. A 3-inch jar wants a thinner wick than a 4-inch jar in the same wax. If you bought a candle whose first burn leaves a rim after 90 minutes, the wick was wrong at the factory. That is not a burn-care problem. That is a spec error, and it is the single most common defect we pull on the line.

What to do when the tunnel already exists

The tunnel is reversible, for about two burns. Wrap the outside of the jar in a strip of aluminum foil, light the wick, and let it run a full cycle. The foil reflects heat back into the rim and the solid ring melts into the pool. Remove the foil after the session and let it cool fully. You get one clean burn back, and the scent comes with it. If the tunnel is deeper than a third of the column, or the flame now sits below the wax line, stop. The wax is stranded and the burn is unsafe. This is also why you stop a candle at 1/4 inch of wax left: the glass is doing the heat dissipation, and past that point it cannot keep up, and the jar cracks on the next burn.

One more thing our line checks before a jar ships: the wick should be cut to 1/4 inch before every burn. A long wick makes a tall flame that over-pulls and soots. A short wick starves the pool. The middle is where the pool grows the way it should. You did nothing wrong. The first burn just did not run long enough to break the wall it was born behind.