E.I. duPont DeNemours

Upon its founding in 1913, the Hercules Powder Company had eleven plants nationwide, including the “Hercules Works” near Pinole. In 1914, the company closed its venerable Santa Cruz powder mill, moving some of its equipment to establish a black powder production line at the Hercules Works. 

After the dynamite patent disputes were settled in the early 1880s, the American explosives industry descended into a fierce trade war. By the mid-1890s, prices had plunged and the producing firms were nearing ruin.  To survive, the owners formed cartels and other combinations in restraint of trade. Finally, in 1903, the eastern firm of the duPont family, which had acquired an initial stake in California Powder Works in 1869, acquired full control of the company and its major competitors, except the Giant Powder Company. Sales continued under the name of California Powder Works until 1906, when Hercules became a Dupont brand. Production continued at the Hercules and Santa Cruz plants, with the sales office in San Francisco.