Reader Don has the following suggestion:
I found some stuff that I use in one of my hobbies that makes cleaning the copper bottoms of pans effortless and it lasts for a long time see it here.
I used it by accident when I was cleaning my minerals and when I moved the pan away to get more room i was almost blinded when I lifted it off the counter in my shop.
2 things if you try this 1) use lots of cold water to rinse, if you think it’s enough do it 5 times more! 2) after you do this barkeepers friend is all my wife ever uses to keep “her”pans clean
The claim that it will never tarnish again is an interesting one. We’ve ordered some to see how well it works.