How To Make Senko Hanabi Sparklers (very rare Japanese fireworks)

Senko Hanabi sparklers are a type of firework I have put significant effort into perfecting since 2007. I used to build large and complex fireworks regularly, but these little sparklers proved more challenging than even large multibreak shells. The effect produced by a tiny drop of dross that forms on the end of the sparkler is very delicate and even a tiny change in the composition or method of construction causes the result to fail. Finally I have found a method that creates consistent results which I demonstrate in this video. Still, there is room for improvement.

Possible changes to the composition include replacing or supplementing the charcoal with soot (commonly called lampblack) or even graphite. My composition shown in this video contains a higher percentage of oxidizer than most documented Senko Hanabi compositions as I rely on the paper wrapping itself to contribute to the fuel mixture in consuming the potassium nitrate. I have tried a wide spread of compositions including more traditional ratios and found this to work best.

It is not well documented what reaction is the cause of the sparks forming and being ejected from the ball of dross on a Senko Hanabi. I suspect it is a reaction between sulfur dioxide produced by the burning sulfur reacting with carbon in the charcoal to form a variety of byproducts that eject yet unreacted carbon out of the drop where it further reacts in the air. Perhaps catalyzed by remaining potassium salts left over by the potassium nitrate. Here is a paper I uncovered about similar reactions:

Here is another written tutorial for Senko Hanabi that you may find useful:

This is my old video from 2008:

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