Sparkler Candles, How Do They Work?

Saturday, December 10, 2011

I sampled some sparkler candles today. These are narrow cylinders 2.5 mm across and 17 cm long. They burn just like regular candles, but they also sparkle intermittently and relight when blown out. I just had to investigate this strange pyrotechnic device.

on the left, a stripped candle

So I scraped the wax off one of the candles and found some gray flakes (fairy dust!) surrounding the wick. The material could be seen through the thin layer of wax along the entire length of the candle. The sparkling effect suggests that the flakes are metallic. They should also have a low heat capacity and autoignition point, so that even after the flame appears to be extinguished, they are warm enough to continue burning and light the candle again. What are these metallic flakes? I burned a candle to find out.

burning the candle

The white sparks of light were reminiscent of burning magnesium. Magnesium burns at or above 473 °C (883 °F), which is more than sufficient to ignite the paraffin vapor streaming away from a recently-extinguished candle wick.

magnesium turnings on fire

Other metals could be added for a variety of spark colors.

5 Comments

  1. Nara says:

    I didn’t know that u had a blog going on! They seem mostly about computers though; this entry was one of the more interesting one. Post about ur side projects! That would be awesome do read about :)

    1. Jiang Yio says:

      I have been writing less. There are also a dozen incomplete entries that I never got to finish/publish. There might be more time for this stuff during 4th year. I’m glad that you enjoyed reading this :D

  2. Cody says:

    Have you tried to harvest the Mg from these candles? How much is there in one?

    1. Jiang Yio says:

      There isn’t much Mg in there… just a pinch of flakes along the length of the wick. I suspect that there are better sources of Mg.