Gunpowder - Sulfur-free Gunpowder

Sulfur-free Gunpowder

The development of smokeless powders, such as cordite, in the late 19th century created the need for a spark-sensitive priming charge, such as gunpowder. However, the sulfur content of traditional gunpowders caused corrosion problems with Cordite Mk I and this led to the introduction of a range of sulfur-free gunpowders, of varying grain sizes. They typically contain 70.5 parts of saltpetre and 29.5 parts of charcoal. Like black powder, they were produced in different grain sizes. In United Kingdom, the finest grain was known as sulfur-free mealed powder (SMP). Coarser grains were numbered as sulfur-free gunpowder (SFG n): 'SFG 12', 'SFG 20', 'SFG 40' and 'SFG 90', for example; where the number represents the smallest BSS sieve mesh size on which no grains were retained.

The main purpose of sulfur in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be

6 KNO₃ + C₇H₈O → 3 K₂CO₃ + 4 CO₂ + 2 H₂O + 3 N₂