How do trick birthday candles work?

When a person blows out a trick birthday candle, it re-ignites itself in a few seconds. The key about a normal candle that is important to a trick candle is the moment after one blows out a candle. Normally, there is a burning ember in the wick that causes a ribbon of paraffin smoke to rise from the wick. That ember is hot enough to vapourize paraffin but it is not hot enough to ignite the vapour. In a re-lighting candle, a substance is added to the wick to re-ignite it, and it can further ignite the paraffin vapour. The most common substance added is magnesium. Inside the burning wick, the magnesium is shielded from oxygen and cooled by liquid paraffin, but once the flame goes out, magnesium dust is ignited by the ember.