In a burning candle the wax below the flame does not catch fire how
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It's actually really hard to ignite most solids and liquids, because so little is exposed to the air. Even gasoline is harder to ignite than you'd think, because the liquid gasoline cools down the heat faster than the surface molecules can burn. It will put out a match if you dip it in. The only molecules that burn are the ones that evaporate and mix with the air.
There are few enough of those above even a volatile liquid like gasoline. There are still fewer in a candle, where most of the wax molecules are stuck to the other wax molecules.
What you need is a way for the wax molecules to liquefy and spread over more surface area, so they can mix with the air and be ignited. That's what the wick is for. The flame melts the wax at the tip of the candle, then draws it up via capillary action.
Wicks are generally braided, which provides a lot of surface area. A few molecules of the hot wax will evaporate from all that surface area, mix with the air, and only then will the heat cause the oxygen and wax to react. That heat makes the candle self-continuing: more wax is drawn up to replace the wax that has evaporated, and the heat from the last molecule's burn provides enough energy to ignite the next one.
The wick itself doesn't need to burn. It's not providing the fuel. In fact, the wick itself is usually treated with mordanting to prevent it from burning. If it burned, the capillary action would stop and the candle would go out. Wicks have to be specially designed to allow the top of the wick to curl up and burn. Without that, the wick would eventually slump and catch things on fire. Before that design, wicks would have to be trimmed with scissors.
Wax for candles is mixed so as to burn at a pleasant rate. You can dip a wick into gasoline, but it's too volatile and burns out quickly. Even so, a Molotov cocktail doesn't go off all at once, as only the gas on the wick (usually a rag) burns, while the gasoline in the bottle doesn't get enough oxygen. When the bottle breaks, the gasoline is exposed over the whole surface. The whole area catches on fire and you can progress to the looting.
Candles are usually associated less with looting, so they pick a formulation that burns fast enough to make a nice light, but not so fast that it burns out too quickly.
There are few enough of those above even a volatile liquid like gasoline. There are still fewer in a candle, where most of the wax molecules are stuck to the other wax molecules.
What you need is a way for the wax molecules to liquefy and spread over more surface area, so they can mix with the air and be ignited. That's what the wick is for. The flame melts the wax at the tip of the candle, then draws it up via capillary action.
Wicks are generally braided, which provides a lot of surface area. A few molecules of the hot wax will evaporate from all that surface area, mix with the air, and only then will the heat cause the oxygen and wax to react. That heat makes the candle self-continuing: more wax is drawn up to replace the wax that has evaporated, and the heat from the last molecule's burn provides enough energy to ignite the next one.
The wick itself doesn't need to burn. It's not providing the fuel. In fact, the wick itself is usually treated with mordanting to prevent it from burning. If it burned, the capillary action would stop and the candle would go out. Wicks have to be specially designed to allow the top of the wick to curl up and burn. Without that, the wick would eventually slump and catch things on fire. Before that design, wicks would have to be trimmed with scissors.
Wax for candles is mixed so as to burn at a pleasant rate. You can dip a wick into gasoline, but it's too volatile and burns out quickly. Even so, a Molotov cocktail doesn't go off all at once, as only the gas on the wick (usually a rag) burns, while the gasoline in the bottle doesn't get enough oxygen. When the bottle breaks, the gasoline is exposed over the whole surface. The whole area catches on fire and you can progress to the looting.
Candles are usually associated less with looting, so they pick a formulation that burns fast enough to make a nice light, but not so fast that it burns out too quickly.
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