How To Prevent Tunneling & Help Your Candles Last Longer

A candle's container size, wick length, and wax type all contribute to its burn time. Soy wax has a higher melting point than coconut wax, for example, and will take longer to burn. "The higher the melt point, the more hours of burn you'll get, as it takes more time for the wax to liquefy from the heat of the flame," Abigail Cook Stone, co-founder and CEO of Otherland, tells mbg.

The size of the wick is also important: A larger wick means a larger flame, which will burn through your wax faster. (This is why it's important to trim your wick before every use, but more on that later.) "One job of a candlemaker is to ensure that a wick is large enough to melt the full surface of the candle, but not too large that it's drawing up more wax than necessary," Stephen Tracy, the co-founder of Keap, explains. It's a science, people!

Since larger wicks stoke larger flames, you'll want to keep yours trimmed for a steadier, more even burn. Jade Meresz, the product development manager at P.F. Candle Co., adds that trimming your wicks can also prevent smoke and visible soot from forming on the side of your jar. Don't cut your wick too short, though, since it needs to be large enough to support a flame that can melt the full surface of your wax. The sweet spot is around ¼ inch.

You know when a candle looks like it's burning straight through the middle and it's leaving wax on the sides? That's known as tunneling, and it's a sign that you're not burning it for long enough at a time. "Tunneling is typically caused by extinguishing a candle too soon in its initial burns," explains Tracy.

To allow your flame to melt the entire surface of the wax, you should leave it going for at least an hour—especially during those first few burns. "If you stop short, the candle will develop a memory of where the melt pool stopped previously, which can lead to tunneling," says Stone. "Repeatedly burning a candle this way will create a smaller and smaller melt pool each time," adds Meresz.