What is a browning finish on a gun?

Answer 1

Browning is controlled red rust Fe2O3 and is also known as pluming or plum brown. One can generally use the same solution to brown as to blue. The difference is immersion in boiling water for bluing. The rust then turns to black-blue Fe3O4. Many older browning and bluing formulae are based on corrosive solutions (necessary to cause metal to rust), and often contain cyanide solutions that are especially toxic to humans.