The Chemistry of Powder and Explosives - Sciencemadness Dot Org

CONTROL OF RATE OF BURNING 319
Progressive burning coated powders, usually flakes or singleperforated
short cylinders, are made by treating the grains with
a gelatinizing agent, or non-volatile, non-explosive solvent for
nitrocellulose, dissolved in a volatile liquid, generally benzene or
acetone, tumbling them together in a sweetie barrel or similar
device, and evaporating off the volatile liquid by warming while
the tumbling is continued. The material which is applied as a
coating is known in this country as a deterrent, in England as a
FIGURE 80. Cross Section and Longitudinal Section of a Grain of .50
Caliber Extruded Smokeless Powder, Deterrent Coated (25X). (Courtesy
Western Cartridge Company.)
moderant. At the time of the first World War sj/m-dimethyldiphenylurea
was already used widely as a deterrent in rifle powder
intended for use in shooting matches and in military propellants
designed to produce especially high velocities. The substance was
called centralite because its use had been developed in Germany
at the Central War Laboratory at Spandau. The ethyl analog,
diethyldiphenylurea, at first known as ethyl centralite, is usually
called Centralite No. 1 and has generally superseded the methyl
compound (or Centralite No. 2) for use in smokeless powder.
Although many other substances have been tried and have been
Patented, this remains the most widely used of any. Butyl centralite
is a better gelatinizing agent for nitrocellulose than either