WEBVTT - How do candles work?

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<v Speaker 1>Welcome to Brainstuff from how stuff works dot com where

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<v Speaker 1>smart Happens. Hi Am Marshall Brain with today's question, how

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<v Speaker 1>does a candle work? Candles really are an amazing lighting system.

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<v Speaker 1>The fuel itself is the package. There are two parts

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<v Speaker 1>that work together in a candle. First there's the fuel,

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<v Speaker 1>made of some sort of wax, and then there's the wick,

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<v Speaker 1>made of some sort of absorbent twine. The wick needs

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<v Speaker 1>to be naturally absorbent like a towel, or it needs

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<v Speaker 1>to have a strong capillary action like the glass wicks

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<v Speaker 1>that you see in some oil lamps. If you buy

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<v Speaker 1>a length of unwaxed wick at a craft store and

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<v Speaker 1>play with it, you'll find that it feels like soft

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<v Speaker 1>string and that it absorbs water really well. This absorbancy

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<v Speaker 1>is important in a candle because the wick needs to

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<v Speaker 1>absorb liquid wax and move it upward while the candle

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<v Speaker 1>is burning. Paraffin Wax is a heavy hydrocarbon that comes

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<v Speaker 1>from crude oil. When you light a candle, you melt

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<v Speaker 1>the wax in and near the wick. The wick absorbs

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<v Speaker 1>the liquid wax and pulls it upward. The heat of

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<v Speaker 1>the flame vaporizes that wax and it is the wax

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<v Speaker 1>vapor that burns. You can prove that it's the wax

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<v Speaker 1>vapor rather than the liquid wax that's burning. With this experiment.

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<v Speaker 1>The next time you blow out a candle, notice a

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<v Speaker 1>stream of white smoke leaving the wick. This stream is

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<v Speaker 1>paraffin vapor that's condensed into a visible form. It continues

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<v Speaker 1>to form as long as the wick is hot enough

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<v Speaker 1>to vaporize paraffin. If you touch a lit match to

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<v Speaker 1>the stream, even a foot or two away from the wick,

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<v Speaker 1>a flame will run down the stream and relight the wick.

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<v Speaker 1>The reason the wick doesn't burn is because the vaporizing

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<v Speaker 1>wax cools the exposed wick and protects it. You may

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<v Speaker 1>have seen the camping trick where you put a cup

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<v Speaker 1>of water on a fire, or the paper cup won't

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<v Speaker 1>burn because the water inside it cools it. The liquid

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<v Speaker 1>wax does the same thing for the wick, cooling it

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<v Speaker 1>so it doesn't burn up. Paraffin wax will burn on

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<v Speaker 1>its own, but it's like cooking oil or motor oil.

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<v Speaker 1>You have to get it very hot for combustion to begin.

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<v Speaker 1>An oil fire is intense and very hard to put out.

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<v Speaker 1>Paraffin is the same way. In a candle. This works great,

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<v Speaker 1>though only a tiny amount of wax on the wick

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<v Speaker 1>is hot enough to vaporize and burn. For more on

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<v Speaker 1>this and thousands of other topics, does it, How stuff

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