Why Is My Candle Tunneling and How to Fix It

Tunnelling happens when a candle is extinguished before the melt pool reaches the edge, usually on the first burn. Soy wax has a memory and repeats that pool. Fix it by wrapping foil over the top and burning for 2–3 hours until the surface levels.

What causes it

Wax has a memory. The first burn sets the width of the melt pool, and every burn after it follows roughly the same edge. If your first burn lasted forty minutes and only melted the middle, the candle will keep burning down that column and leave a wall of wax around it.

Less commonly, tunnelling comes from a wick that is undersized for the vessel diameter — it simply cannot throw enough heat to reach the edge. That is a manufacturing issue, not a user one.

The foil fix

1. Trim the wick to 5 mm.
2. Wrap aluminium foil around the top of the candle, folding it inward over the rim to form a dome, leaving a hole above the flame.
3. Burn for 2–3 hours. The trapped heat melts the stranded wax down the sides.
4. Remove the foil carefully — it will be hot — and let the candle set completely level.

This recovers most tunnelled candles. If the wall is very thick, it may take two sessions.

Preventing it

Give the first burn two to three hours, or however long it takes for the pool to reach the edge. Set aside the time before you light it — a candle lit twenty minutes before you leave the house is a candle you have already damaged.

When it cannot be fixed

If the wick has burned down inside a deep well and can no longer be lit, the candle is finished. You can melt the remaining wax out in a warm water bath and reuse the vessel — see our guide on cleaning and reusing candle jars.

Frequently asked questions

Can a tunnelled candle be saved?

Usually yes. Wrap foil over the top leaving a hole above the flame and burn 2–3 hours; the trapped heat melts the stranded wax down.

Why does my candle only melt in the middle?

The first burn was too short to let the pool reach the edge, and the wax now repeats that shape. Soy wax has a memory.

How long should the first burn be?

Long enough for the pool to reach the edge — typically 2–3 hours for a standard jar.

Does tunnelling waste a lot of wax?

It can strand 30–40% of the candle against the walls, which is why the first burn matters so much.

Is tunnelling dangerous?

Not directly, but a wick burning deep in a well overheats the vessel base and can crack glass. Fix it or stop using it.