| Search our quarter-million Q&As |
Home of the finishing HOTLINE since 1989
-----How to tell whether it's blued vs. painted
Quickstart:
"Bluing" (also called "black oxiding") is a process where parts are immersed in a very hot (230+ °F) solution, heavy in caustic soda and nitrates and/or nitrites to build a stable black rust on them. If the parts are rather matte to start with, they'll usually look black; if the parts are highly polished, they usually come out with a jeweled navy blue look.
Although bluing is not very corrosion resistant except when waxed or oiled, it is attractive, and the coating is very very thin, almost never affecting any clearances or tolerances.
"Cold bluing" / "room temperature blackening" is a process which simulates hot black oxiding, but is not as corrosion resistant, thin, or free from smut.
Q. I'm restoring an antique typewriter. Some of the parts have a black matte finish. How can I tell whether they are blued or just painted?
Alex T.Hobbyist - Hartford, CT
September 15, 2025
This is a meeting place for camaraderie & sharing, not a free consultancy. So some readers don't engage with anonymous posters.
A. Try solvents like acetone or white spirit or paint stripper on it; if it can be dissolved then it is paint, patinas are resistant to most solvents.Hope it helps and good luck!
Goran Budija- Cerovski vrh Coatia
September 23, 2025
Sorry! Finishing.com is temporarily Read-Only.
Ted Mooney is retiring but I have several offers to take it over.
We're working hard to make sure we find it the best new home.