When I do the old method involved with "Rust Bluing" the BLACK oxidation is formed
after the parts have been treated with a rusting agent, and then boiled in distilled water for a certain amount of time.
After several coats of solution and then boiling are applied and the final result of color is achieved, then, and only then is the bluing coated with a rust stopping solution to prevent further rusting.
If, and when, this process is completed after around 8 or 9 applications, the end result will last much better than hot-dip bluing, like so:
I rust blued this Stevens 1915 Favorite over 10 years ago and it's held up just fine.
This Mauser 98 action was rust blued over 20 years ago and has held up just fine through 20 gun deer seasons without rubbing off:
