How to blacken brass, advice needed.
 

I want to make some brass parts black. I bought some commercial stuff that is supposed to do that. Tried it out, yep, it turns the brass parts really black, BUT... There is about zero durability in the coating. Rubbing it even slightly takes off nearly all of the black color. Disappointing.

Am I doing something wrong with surface prep? I tumbled the parts in a deburring tumbler, then washed them down with solvent before soaking in the solution. Do I need to do something like sandblasting them before treatment? Something else?

Are there better and lesser brands of blackening solution out there? If so, what's a good brand?

Is there an electrolytic process like anodizing for aluminum that works on brass?

Got to get something better than what I have now. Open to suggestions.

Re: How to blacken brass, advice needed.
 

Acid dipping will do the job, although I can't remember which one: hydrochloric or sulphuric. One will clean, the other tarnish. lightly sand first to remove the patina.

Re: How to blacken brass, advice needed.
 

Thanks for the info but hydrochloric acid is kind of a non-starter. I have worked with it before and didn't ever like the experience. All kinds of hazards. Not in my job jar if I can ever avoid it. Sulphuric I can handle. (Battery acid.)

Also I am kind of looking for really black, not just tarnished. (I can get tarnished just by leaving it out in the weather for a couple of weeks.)

The "lightly sand" is kind of an interesting idea. I can get that with sandblasting. May give it a try and see if that makes things better.

Re: How to blacken brass, advice needed.
 

Birchwood-casey makes a product 'brass black' that i'd probably try first.
https://www.youtube.com/watch?v=PQqRKX2dWWI

There are some antiquing and patina fluids out there that are more hobby level

Or you there are some industrial systems out there if you had the setup to make it work and weren't just doing one-offs. Talk to machine shops if you want that?