Why Is My Candle Tunneling? Causes and Fixes
A candle tunnels when it burns a narrow hole down the middle and leaves a wall of hard wax around the sides. The usual cause is a first burn that was too short. You can fix most tunneled candles in one evening, and you can stop the next one from doing it in the first place.
Why candles tunnel
Wax has a memory. On the first burn, the melted pool spreads out from the wick until you blow the candle out. On every burn after that, the flame tends to melt down through the same circle instead of spreading wider. If the first burn only melted a pool the size of a coin, the candle will keep digging that coin-sized hole until it reaches the bottom, and the wax on the sides never gets used.
Soy wax is more prone to this than paraffin because it is softer and melts at a lower temperature, so the edges stay solid more easily. The other causes are a wick that is too small for the jar, a draft that pushes the flame to one side, and lots of short burns.
How to prevent it
Let the first burn run until the melted wax reaches the edge of the jar all the way round. A common rule is about an hour for every inch of jar width, so a 3 inch jar needs two to three hours. Do the first burn on an evening when you will be home and awake for that long. After that, keep each burn going until the pool reaches the edges again, and stop at four hours.
How to fix a tunneled candle
The foil trick
Wrap a strip of aluminum foil around the top of the jar so it covers the outer edge of the wax and leaves a gap in the middle for the flame. Light the candle. The foil holds the heat in and melts the wall of wax on the sides. After an hour or two the surface should be level and liquid to the edge. Take the foil off carefully, because it will be hot, and let the candle cool. The next burn starts fresh.
The hair dryer method
If the tunnel is shallow, point a hair dryer at the top of the candle on a warm setting and move it around until the top layer melts flat. Let it set, then do a full burn to the edges next time. Keep the dryer moving so the wax does not splash out of the jar.
Even out a deep tunnel
When the tunnel is deep and the wick is buried, scoop out a little wax from around the wick with a spoon so the wick sticks out about a quarter of an inch, then use the foil trick. Do not try to dig the whole wall out. It is easier to melt it down.
When the wick is the problem
If you did a full first burn and the pool still never reaches the edges, the wick may be too small for the jar. That is a fault in the candle. Our candles are made with a cotton wick sized for the jar, and if one tunnels after a proper first burn, email us and we will look into it.
Frequently asked questions
Can a tunneled candle be saved?
Almost always. The foil trick fixes most tunnels in one burn. The only lost cause is a candle that has tunneled to the bottom and drowned its wick.
Why is my candle tunneling on the first burn?
The pool needs time to reach the edges, and it starts as a small circle. If you look after twenty minutes it will look like a tunnel. Give it the full two to three hours before deciding.
Does trimming the wick cause tunneling?
No. Trim to about a quarter of an inch. A wick cut much shorter than that can make a small flame and a narrow pool, so do not overdo it.
Is tunneling dangerous?
Not on its own, but a deep tunnel can drown the wick and a lopsided pool can heat one side of the glass. Fix it rather than burning it lower and lower.
More on getting the full burn time in how long a 9 oz soy candle burns, and the short version on our candle care page.