Mixing
Mixing the three ingredients -saltpetre, sulphur, charcoal together -'green charge'.
Incorporation
Pulverising and grinding together the green charge under edge runners in the incorporating mill to obtain the closest mix possible- mill cake.
Fundamental process - improperly incorporated material will make the following operations useless.
Breaking Down
Putting the mill cake into more even form, in breaking down machine, for pressing meal.
Pressing
Meal is subjected to pressure in hydraulic presses, to prepare for corning - press cake.
Purpose of pressing:
Increases closeness of mix - better explosiveness.
Increases density - prevents mix falling apart in transport and handling.
Makes less hygroscopic, moisture absorbing.
Produces more grains when corned - less dust.
Increases volume of exploding gas - more power.
Corning or Granulating
Transforming the press cake into grains in corning machines.
Performance of gunpowder depends on size and shape of grains.
Produces uniformity, essential for controlled operation and predictability of firing.
Grains, containing moisture and dust, are termed 'foul grain powder'.
Dusting and Glazing
Dust is removed from the foul grains in dusting reels.
Reduces moisture absorption and therefore improves transportation and storage quality.
Action of dusting removes grain imperfections, corners and protrusions, which would form dust. This also creates the spherical shape which gives best performance.
For some larger grain sizes a small amount of graphite is added in glazing barrels to impart a hard glazed finish. This aids moisture resistance and also slightly retards ignition, to avoid damage to gun.
Stoving or Drying
Final moisture removal by drying in steam stoves - rooms with steam pipes.
Heading Up
Dried gunpowder is put into 100 Ib. barrels.
