Gunpowder Grades

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2FA, 3/4FA, 5FA and Meal D Gunpowder (homemade)
2FA, 3/4FA, 5FA and Meal D Gunpowder (homemade)

Black powder that passed through the steps of pressing to a known density (generally about 1.7-1.75g/ccm) and breaking down again, is finally separated by grain size using a nest of screens.

Due to practical considerations (physical properties etc.) and with a view to simplification (comparability, reproducibility etc.) particle size ranges of different grades of gunpowder were standardized (although commercial manufacturers still slightly deviate from each other). Different grades show distinct burning characteristics and are used for different purposes.

Table : Different grades of gunpowder (after GOEX standard)

Grade: through (mesh): on (mesh): Particle size range (microns): Popular uses (examples):
FA 3 1/2 5 5660-4000 uncommon, lifting very large calibre shells
2FA 4 12 4760-1680 lifting shells, breaking cylinder shells
3FA 10 16 2000-1190 lifting shells, lifting/breaking cake items, inserts
4FA 12 20 1680-840 lifting shells, comets, stars, lifting/breaking cake items, shell inserts
5FA 20 50 840-297 lifting stars; dipping primed crossettes, comets
6FA 30 50 595-297
7FA 40 100 420-149
Meal D 40 - <420 priming stars, finished devices; used in fountain/star comps; charging spolettes
Fine Meal/Flour 100 - <149 blackmatch manufacture
Extra Fine Meal/Flour 140 - <105 blackmatch manufacture

On nomenclature: The number of "F"s indicates the particle size of grain powders; the more Fs, the finer the grain. Sometimes e.g. a 4FA gunpowder is also written FFFFA, especially in some of the older publications. "A" indicates the fact that the powder contains potassium nitrate as the oxidizer, in contrast to so called "B" blasting powders using sodium nitrate, which are not normally used for fireworks. Graphite polished cannon grade powders are denoted replacing FA with "Fg", and e.g. a 4Fg shooting powder would be as fine as a 7FA fireworks powder. Fireworks powders are not normally polished, although polished grain sometimes can be found in consumer articles.

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