Everyday Chemistry - What’s the magic behind trick birthday candles?

If it's your Birthday, you have to blow all the candles lit on the cake as a ritual. But the situation is a little different when it comes to magic candles. The more you blow them the more they relight. Is this magic or simply chemistry? Let's find out!

The trick

All candles are made out of paraffin wax or candle wax as we call them. Every candle has a wick to burn. The difference between a normal candle and a trick candle is what happens when you blow it. When you blow a normal candle, a thin ribbon of smoke rises from the wick. This is nothing but vaporized candle wax. The wick is hot enough to vaporize the paraffin of the candle but not hot enough to re-ignite the blown candle.

Trick candles work a little differently from a normal candle. The wicks of this candle have a special material, which ignites at a relatively low temperature. When you blow a trick candle, the left over heat from the wick re-ignites this special material and the candle starts burning again. The flame that burns after blowing out the trick candle is burning paraffin vapour.

Meet the special material in trick candles

The special material added to the wick of trick candles is usually flakes of magnesium. Magnesium doesn't require too much heat to start burning, just 800 to 430 degrees. The magnesium flakes start burning when you blow out the candle and ignite the vaporised paraffin. When you blow out the candle, the magnesium flakes appear as tiny particles on the wick and the magic begins.

One particle is enough to re-start the spark and in turn re-ignite the vaporised paraffin. The magnesium in the rest of the wick does not burn as the liquid paraffin separates it from oxygen and keeps it cool.

There is nothing magical about trick candles; just pure chemistry. So the next time you blow out a magic candle, you know why the flames reappear!