The Chemistry of Powder and Explosives - Sciencemadness Dot Org

330 SMOKELESS POWDER
After the material has cooled, the powder grains are transferred
in a slurry to another still and are treated with an emulsion of
nitroglycerin dissolved in toluene, or of some other coating agent
dissolved in a solvent in which nitrocellulose itself is insoluble,
and the volatile solvent is distilled off, leaving the nitroglycerin
or other material deposited on the surface of the grains. As much
nitroglycerin as 15% of the weight of the powder may be applied
in this way. A coating of centralite may, if desired, be put on top
of it. The grains are sieved under water and are then dried for
use in shotguns. If the powder is to be used in rifles, it is passed
in a slurry between warm steel rollers by which all the grains are
reduced to the same least dimension or web thickness. Previous
to the drying, all the operations in the manufacture of ball-grain
powder arc carried out under water, and are safe. After the drying,
the operations involve the same hazards, by no means insurmountable,
as are involved in the ordinary process. The grains
are glazed with graphite and blended.