mixture was then fed through a press extruding a long tubular cord form to be cut into grains of the desired length. Alcohol and ether were then evaporated from "green" powder grains to a remaining solvent concentration between 3 percent for rifle powders and 7 percent for large artillery powder grains. Burning rate is inversely proportional to solvent concentration. Grains were coated with electrically conductive graphite to minimize generation of static electricity during subsequent blending. "Lots" containing more than ten tonnes of powder grains were mixed through a tower arrangement of blending hoppers to minimize ballistic differences. Each blended lot was then subjected to testing to determine the correct loading charge for the desired performance. Military quantities of old smokeless powder were sometimes reworked into new lots of propellants. Through the 1920s Fred Olsen worked at Picatinny Arsenal experimenting with ways to salvage tons of single-base cannon powder manufactured for World War I. Olsen was employed by Western Cartridge Company in 1929 and developed a process for manufacturing spherical smokeless powder by 1933. Reworked powder or washed pyrocellulose can be dissolved in ethyl acetate containing small quantities of desired stabilizers and other additives. The resultant syrup, combined with water and surfactants, can be heated and agitated in a pressurized container until the syrup forms an emulsion of small spherical globules of the desired size. Ethyl acetate distills off as pressure is slowly reduced to leave small spheres of nitrocellulose and additives. The spheres can be subsequently modified by adding nitroglycerine to increase energy, flattening between rollers to a uniform minimum dimension, coating with phthalate deterrents to retard ignition, and/or glazing with graphite to improve flow characteristics during blending. Modern smokeless powder is produced in the United States by St. Marks Powder, Inc. owned by General Dynamics. See also Antique firearms Brown-brown Small arms References Bibliography External links The Manufacture of Smokeless Powders and their Forensic Analysis: A Brief Review. Robert M. Heramb, Bruce R. McCord Hudson Maxim papers (1851–1925) at Hagley Museum and Library. Collection includes material relating to Maxim's patent on the process of making smokeless powder. Cordite Explosives Firearm propellants Solid fuels Powders