How do you remove black tarnish from steel window frames in my art deco era apartment?

I've gotten through the time consuming task of removing the 800 layers of what probably is lead paint, and have had some success with sanding, but it takes even longer then the stripping to get down to the shiny metal.  I think this is some kind of tarnish?  If so, is there a product someone could recommend, or am I committing to another 800 hours of elbow grease?  Many thanks in advance!

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Vyger4 years ago
Are you sure its not galvanized? The galvanized coating on steal often turns dark after years. And it is usually not a uniform color. It is done that way to keep the metal underneath from rusting.
ArtDecoSteelFrames (author)  Vyger4 years ago
It might be galvanized... I never thought of that before. It is an inconsistent black, which makes me think you might be right. Although, after a quick search on the web - it might also be "black oxide"?

Regarding damaging the metal, I put a coat of clear poly on the window frame I finished and haven't had any trouble (that was over a month ago). I hope that is sufficient? Prior to the poly it definitely rusted when the window was open.

If it is galvanized or "black oxide", any recommendations for removing? Many thanks again for everyones recommendations.
Kiteman4 years ago
Wire brush on a dremel or hand-drill?
ArtDecoSteelFrames (author)  Kiteman4 years ago
I've tried both. After hours of work (literally an entire day with two people) We finished one frame down to the shine. I've tried 40# sandpaper, 120# sandpaper for metal, and they both take a concentrated half hour in one small section to remove.
That black coating is there for a reason. If you strip it off the metal will start rusting and you will be creating problems for yourself.
Burf4 years ago
You can try white vinegar but if you don't mind using something a little stronger, naval jelly will almost certainly do the job. Its been around for as long as I can remember and has always worked well for me.
Just be sure to read and follow the label instructions.