How to Fix Candle Tunnelling

Tunnelling is when a candle burns a well down the middle and leaves a wall of unused wax on the glass. You are wasting fuel and the scent goes thin, because there is not enough melt pool to throw. It is almost always the first burn being too short, or a wick that cannot reach the edge of that jar.

We pour soy-coconut in Ullapool. The same rules apply to most container candles.

Fix a tunnel that has already started

1. Trim the wick to about 5mm. A mushroomed wick will not save you.
2. Wrap the jar in foil, tented, with a hole over the flame. The foil reflects heat onto the walls so the stuck wax starts to slump.
3. Burn until the pool reaches the glass, or as close as you can get without the jar becoming too hot to hold at the sides. That can take two or three hours in a wide tin. Stay in the room.
4. If the walls are still high, stop, let it set, and repeat once. Do not keep a roaring flame going all evening hoping it will catch up.

Some people oven-melt the top. We do not recommend it. Jars crack, fragrance cooks, and you have a tray of hot wax in a domestic oven. Foil is slower and safer.

Stop it happening

The first burn sets the memory. Let the pool reach the glass before you blow it out — roughly one hour per 2–3cm of diameter as a starting point, then use your eyes. After that you can do shorter burns, but if you keep snuffing it at twenty minutes you will train a well.

Keep it off draughts. A flame pushed to one side eats a trench, not a circle. That is in draughts and memory burn.

If a brand new candle tunnels on a long first burn, the wick is undersized for the wax and the jar. That is a making fault. Ours are wicked for soy-coconut in the jars we actually use — Ullapool and the rest of the landscape lot.

Quick answers

Can I microwave it? No. Metal wick tabs, uneven heat, cracked glass.

Do I need a heat gun? Only if you make candles. For a house candle, foil and time.