Before, and after.
They dirtied it?
Smartass.
They Parkerized it. From their advent through the start of World War II, M1911s were Blued. Originally they received a "Charcoal Bluing," which is gorgeous, but it's labor intensive and shiny. Shiny is not good in combat. It draws attention, which tends to be fatal. So by the end of WWI, at the government's insistence, the pistols were nearly matte black in color. Then the Government cancelled the contracts. The "War to End All Wars" was over so they didn't need pistols.
By the time Hitler had taken Austria, Czechoslovakia, Hungary, Poland, and France, the geniuses at the War Dept began to think they might should stock up on pistols, just in case this Hitler turned out not to be a flash in the pan. So they started to rev the manufacturing engines in 1941. Fortuitously enough, right about this time a fella named Darcy who worked for the Parker Rust Proof Company had filed a patent for a new acid-etching process that used phosphoric acid and zinc to cause a dark gray and extremely rust resistant finish to form on metal. It was far more durable than bluing, but was cheaper and required less labor. It wasn't as pretty as the Charcoal Blue finishes of early M1911s, but the prettiest gun in the world is the one that works after it's been through the mud, blood, and gore of combat and saves your ass when you're under fire. Parkerized guns don't mind mud, blood and gore at all. So all Government Model 1911s manufactured after 1941 and until the geniuses again cancelled the contracts in 1945 - like mine, which is from 1943 - were Parkerized when they left the factory.