We realized the copper is just a plating over steel, and that some of the black isn’t coming off. So after a bit of googling we think they actually are a type of finish from the Victorian era popular when our house was Reno-ed called “jappaned”. It’s copper and black designs plated over steel and then lacquered. Pretty cool.
Apparently you should never use abrasives (ie steel wool) to clean these fancy finishes, and you shouldn’t let them “cook” in the slow cooker for 12 hrs either. Lesson learned!
We also picked thru our vintage hardware collection to start figuring out what to put where.