Brass/bronze door: cleaning and refinishing?

I have a brass-looking door on a building. It’s become very corroded over time, in various places. I tried to stick a magnet to it to make sure it wasn’t a coated metal. The magnet didn’t stick, so I figured I was safe.

I tried using a paste of salt, vinegar, and flour to clean off the corrosion. However, when I cleaned it off, it looks like it’s bronze or copper underneath.

I have included before and after pictures at the top.

I have a few questions:

1. What is this? Is it copper coated in brass?

2. Is there any way to clean this and preserve the golden color?

This is actually a door to a historical landmark, so I would like to preserve the color of the door if possible. If there is something I can do myself to handle it without hiring a professional metal worker, that would be awesome, but if I have to hire a professional then I will.

 

I "think" that is caused by oil build up from peoples hands corroding it . I once worked at an old restaurant where one of the wait staffs duties was polishing the doors and rails every shift. it was beautiful,then I saw it 20 years later very run down and the metal looked like this. Im not sure what you could do to clean it if its seeped in .

 

The condition looks very similar to what I have seen on scientific instruments with a deteriorating lacquer coating. As you found out, if you scrub it off you are left with the original color of the bare metal. To restore it, you would need to recreate the colored lacquer coating. As this is on a historic building, I would strongly recommend that you find a conservator experienced in the conservation of historic metals. Historic lacquers and patinations can be complex, and unfamiliar to most modern metal workers. I am reminded of a late 19th century chandelier that hung in a museum I worked in. It was patinated in a lovely antique green color. After an unfortunate leak, the director sent it out to be "restored" (without my knowledge). It came back highly polished, with no trace of the orginal color left, and exposing a distracting combination of brass and copper elements. Very sad.

Also, please avoid using salt as an abrasive on metals. Unless you can thoroughly wash off any residue, you may end up creating additional corrosion problems.

 

Not an expert but that looks like a cheap gilded brass structure held together with phillips head screws and looks like it was made in the fifties. If the "Historic landmark" is older than that then my feeling is that this is a more modern replacement probably meant to jazz up the entrance for tourists.