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making and using of star and flame formulas


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#1 newtoolsmith

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Posted 25 March 2006 - 11:41 AM

Hi friends,

while reading the topics about star and coloured flame formulas I noticed that the adequate mixing method was told nowhere.

Even particle sizes and such things are missing.

For this reason I suggest to collect and rearrange new and old posts here including some additional information.

Unfortunately I am not the best source for such formulas and someone else should start.

MfG
newtoolsmith

#2 alany

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Posted 26 March 2006 - 07:27 AM

For stars the particle size is typically "as fine as possible", only metal particle sizes are especially critical. Typically running the composition through a 20 mesh screen a few times is all that is required for mixing.

Oxidiser particle size is actually less critical than that of fuels. Oxidisers usually melt before decomposing, the liquid phase is quite critical to almost all pyrotechnic reactions. Finer oxidiser still increases burning speed, but it is much less dramatic than with fuels. -100 mesh is good-enough for most purposes.

An exception might be torches, some lances and pinwheels who's correct operation depends on having quite coarse material, especially Sulfur and Potassium NItrate.

The binding system is usually the least documented aspect of a composition. Some compositions (e.g. glitters, go-getters, crackle cores) are quite sensitive to the solvent used. Some compositions aren't bound at all, but are rather pressed, i.e. Mg illumination comps. Sometimes it is obvious, with Dextrin, SGRS or Starpol making up 2-6% of the composition, other times the binder is omitted completely, like falls composition or some granite stars requiring you to check the original text to see they need gum water or shellac/redgum binding.




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