Tunnelling- Why does this happen?
Tunnelling is generally a bad and annoying thing for most candle lovers. When burning a candle the goal is the have a smooth and even surface around the whole candle. When a candle tunnels, you’re wasting a lot of wax on the side and therefore not really getting your money’s worth. Once this happens it’s almost impossible to rectify unless you scoop the waste out and beginning burning the candle with a even smooth surface.
So how can you stop this happening?
In most cases the candles are poorly made and will tunnel no matter what you do, and this is mainly due to wick size/quality of wax/scent. In the above picture, the wicks are a little too small for the jar. Three wicks would have been better considering the size of the container, and you would get a much better even burn. Instead, it started to tunnel.
It’s all about the wax pool?
What is a wax pool?
A wax pool is the liquid wax that forms once you begin burning an candle. This wax pool will increase as the candle burns for longer. The more liquid in the pool(for scented candles) the stronger the aroma as its using more wax and therefore scent. Different manufacturers will use different scent strengths and therefore this can vary.
Sometimes tunnelling happens due to the very first time you’ve lit your candle. You may be allowed it to burn in perhaps 30 minutes or less and blew it out for whatever reason and didn’t get a good wax pool going. Candle wax has “memory” and the next time you light your candle, it will “remember” how far the previous wax pool was and only melt to that point. What you need to do is on that first burn; allow the candle to stay lit until there is a complete and even wax pool, meaning the wax has completely melted to the edges of the container. Otherwise, it will melt through the centre of the candle, wasting a lot of wax. I’ll show you what I mean in a picture.
But let’s see how you can fix this? The best way to do it is by getting some aluminium foil and wrapping it around the candle, making a dome shape on the top. This is only recommended with supervision and by watching the candle until the process (complete wax pool) is complete. Then remove the foil and your burn should be even.
Reference from “how-to-fix-a-candle-after-it-tunnels”