Brown Oxide to black patina oxide

[PEU]

Reading the forum I congratulated @Greenberg Woods about his chemist degree and remembered this doubt I have. Maybe Larrin can chime too.

How does the conversion of brown oxide to black oxide (patina) works?, AFAIK in chemistry language is Fe2O3 to Fe2O4

And why the doubt? Because if I knew the process I could do better forced patina on my knives and also because I like to learn new things

Thanks

Pablo

 

[Larrin]

Look at "rust bluing": https://en.m.wikipedia.org/wiki/Bluing_(steel)

 

[A.McPherson]

I've done it a couple times with varying degrees of success...

Basically I used a mix of hydrogen peroxide, salt and vinegar to rust my steel. Once I got a good later of non-crusty rust, you boil it in water till it turns dark. Repeat until you get a nice dark coating. Then oil.

Simple process, hard to get right.

If done right you get a nice smooth dark black coating. Done wrong you get a patchy dark coating with pits. Still black though.

 

[PEU]

Thanks a ton guys! will experiment!

Pablo

 

[Bill DeShivs]

Your red/brown rust should be carded with de-oiled steel wool. after boiling. The entire process may need to be repeated several times to get the shade you want.