From PyroGuide
Chrysanthemum 6 cut stars for use in shells
This page collects some formulas for charcoal based fire dust compositions. There are many advantages with such formulations e.g. the ingredients are cheap and generally non-toxic, the stars are easily consolidated with a water-based binder and show high ignitability, the stars are less sensitive to shock and friction than the coloured ones (that means: they are safer to use) and so on.
Moreover the beauty of the effects should not be underestimated. Well made charcoal effects (often japanese in origin) frequently score off numerous colour breaks in displays and e.g. a good willow shell regularly is the highlight of the night.
Some of the effects are already covered by other articles in this community, so I donĀ“t recapitulate the manufacture etc. in detail. It must be noted that for some effects special manufacturing methods (milling, wet methods etc.) are necessary to obtain good results and in this cases it is not enough to screen the ingredients together, failing which the effect will generally suffer (less sparks, less delay etc.). Regarding manufacturing methods the reader is refered to the specific articles in this section.
A word on charcoal: For spark effects it is common to employ hardwood charcoals. While pine charcoal is said to give the best fire dust streams, it is also true that sources for good material are often hard to find. Alternatively other hardwood charcoal is recommended, with e.g. beech giving very good results. Suitable charcoals are discussed in the Charcoal Suitability Table.