Black powder moisture content

Figure 2.2 Influence of moisture content on black powder burning time.

Black powder can vary from brand to brand. Variations in percentage compositions between manufacturers are small, but different charcoals, types of saltpeter (purity), different moisture content, and so forth can result in different ballistic performances from basically similar mixtures. Owing to a temporary shortage of potassium nitrate during World War I, sodium nitrate was used as a substitute. Ammonium nitrate has also been used as a substitute for potassium nitrate. 

If the Mn02 layer deposited according to Eq. (44) at the anode surface reaches a thickness of 20-30 mm, it is removed mechanically and processed to a black powder showing the following features typical content of Mn02 (mostly the hexagonal e-modification) 91 wt% moisture 3-5 wt% sulfate content up to 1.3 wt% iron <0.02 wt% Pb, Cu, Co <0.001 wt% particle size <75 xm and BET surface 40-50 m g-l. 

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