How do I restore these window sills?

[Citro]

Hello
I have a house with windowsills as shown in the picture that have started to oxidize and generally look worn. Cannot be cleaned with regular soap water.
I guess they are copper?
Is it possible to restore or improve them somehow? Thought I'd check here before going at them with vinegar and ketchup! ☺️

 

[Hep]

I would have tried copper polish. I've never done it and have no knowledge, but the name makes me start with it.

 

[cpalm]

Copper "should" look like that.

Trying to maintain the "copper shine" requires polishing and applying clear coat. But I've never heard of doing that in construction contexts.

 

[Citro]

Copper "should" look like that.

Trying to maintain the "copper shine" requires polishing and clear coating. But I have never heard of anyone doing that in construction contexts.

Yes, hoping to achieve any form of copper shine is probably too much to ask for.
I'm actually satisfied with the brown/black part. It's the oxidized spots that are bothersome.

 

[cpalm]

I'm actually satisfied with the brown/black part. It's the oxidized spots that are bothersome.

The brown vs. green are different stages in the oxidation process. Depending on air pollution and such, over time it will become completely green.
There's probably nothing you can do to get a completely homogeneous color tone, so the patchiness should probably be seen as normal "patina."

 

[Citro]

Okay. Then I know a little more. Thanks for the help!
I will wash them off and then let them be for now.

 

[datja]

Copper tarnishes. That looks nice. But you can use copper polish if you want it red and shiny for a year or so.