Welcome to Brainstuff from how stuff works dot com where smart Happens. Hi Am Marshall Brain with today's question, how does a candle work? Candles really are an amazing lighting system. The fuel itself is the package. There are two parts that work together in a candle. First there's the fuel, made of some sort of wax, and then there's the wick,
made of some sort of absorbent twine. The wick needs to be naturally absorbent like a towel, or it needs to have a strong capillary action like the glass wicks that you see in some oil lamps. If you buy a length of unwaxed wick at a craft store and play with it, you'll find that it feels like soft string and that it absorbs water really well. This absorbancy is important in a candle because the wick needs to absorb liquid wax and move it upward while the candle
is burning. Paraffin Wax is a heavy hydrocarbon that comes from crude oil. When you light a candle, you melt the wax in and near the wick. The wick absorbs the liquid wax and pulls it upward. The heat of the flame vaporizes that wax and it is the wax vapor that burns. You can prove that it's the wax vapor rather than the liquid wax that's burning. With this experiment. The next time you blow out a candle, notice a stream of white smoke leaving the wick. This stream is
paraffin vapor that's condensed into a visible form. It continues to form as long as the wick is hot enough to vaporize paraffin. If you touch a lit match to the stream, even a foot or two away from the wick, a flame will run down the stream and relight the wick. The reason the wick doesn't burn is because the vaporizing wax cools the exposed wick and protects it. You may have seen the camping trick where you put a cup of water on a fire, or the paper cup won't
burn because the water inside it cools it. The liquid wax does the same thing for the wick, cooling it so it doesn't burn up. Paraffin wax will burn on its own, but it's like cooking oil or motor oil. You have to get it very hot for combustion to begin. An oil fire is intense and very hard to put out. Paraffin is the same way. In a candle. This works great, though only a tiny amount of wax on the wick
is hot enough to vaporize and burn. For more on this and thousands of other topics, does it, How stuff works dot Com