Candle Tunneling: Why it Happens and How To Fix it

Tunneling can happen to even the best, most tried-and-true candles. When you don’t burn a new candle long enough to allow the entire surface to melt evenly, the wax pool only melts in the center, forming a “tunnel” or sinkhole straight down the middle. Here's everything you need to know about tunneling and the candle care techniques that prevent it.

Problems Caused by Candle Tunneling

1. As the wick sinks and melts the surrounding wax above, the wax can drown the wick and make it hard or impossible to light.
2. The candle’s lifespan is shorter because only a portion of the solid wax gets melted.
3. Perfectly good, unused wax remains stuck to the sides of the candle container after the candle has burned down.

How To Prevent Candle Tunneling

The first time you light a candle, allow it to burn long enough to melt the wax to the edge of the container (or within 1/4 inch), creating a full melt pool. This first lighting is called a “memory burn” since the candle remembers its first melt pool. Depending on the size of the container, this can take several hours (roughly one hour for every inch in diameter).

Doing this every time you light it will help the candle burn evenly throughout its lifespan, but the initial burn is the most important. Another way to prevent candle tunneling is to always trim the wick to 1/8 inch (for wooden wicks) or 1/4 inch (for cotton wicks) before each use. Otherwise, carbon buildup will cause the candle to smoke, throw soot, and burn too hot, which can also cause tunneling.

How To Fix Candle Tunneling

The Foil Method

1. Cut a square of aluminum foil slightly wider than your candle.
2. Fold the square in half and cut a circle out of the center, leaving an inch or two of foil around it (more or less, depending on the size of the candle’s container). 
3. Open the square flat again and lay the foil on top with the hole centered over the flame. Fold the edges of the foil down to hold it in place.
4. Light the candle. The foil will allow the flame to slowly melt the remaining wax off the sides. If this drowns the wick, blow out the flame, use a cotton ball to remove some of the melted wax, relight, and repeat as necessary. 
5. Once the candle surface is level, wait at least 24 hours for the wax to fully harden before relighting.

The Hair Dryer/Heat Gun Method

A heat gun is best, but a hair dryer will do in a pinch.

1. Turn on the hair dryer or heat gun and melt the top of the candle in a circular motion, turning it with the other hand as you go. Be careful, and use an oven mitt if necessary.
2. As the leftover wax melts down from the sides of the candle, it may drown the wick. If this happens, use a cotton ball to remove some of the melted wax.
3. Continue until the candle surface is level.
4. Wait at least 24 hours for the wax to fully harden before relighting.

Prevention is Key

The easiest way to avoid tunneling is to keep it from happening in the first place by doing a memory burn on the first lighting, always trimming the wick, and keeping it lit long enough during each burn. But don't worry if only 1/4 inch of wax remains on the sides after the first burn. Since the flame creates more heat as a candle burns down, most of that wax should melt by the time the candle is spent. But if your candle does tunnel, now you know how to fix it with some aluminum foil or a little heat!