apply Black Oxide to carbon steel, stainless steel, copper, brass and zinc die cast. We work directly with prime government contractors, manufacturers, job shops, machine shops... and tool & die shops. Our customer include: Hughes, General Dynamics, Rocketdyne, GM, Ford and Chrysler. Permits issued by US-EPA, CAL-EPA, LAPD, LAFD, US-ATF, SCAQM, CIty of LA- Bureau...