There is a secret trick to keeping copper bottom pans nice and shiny all the time. First, you need to clean all of the cooked and caked-on food and/or grease off of the pan like you would any other pan.
After you are finished with that, you will need a fresh lemon, and not lemon juice in a plastic squeezer, and table salt. Wet the bottom of the pan with the lemon juice and sprinkle the salt on it.
You will see automatically what happens. The dark color just rolls off with the juice. In order to make this happen faster and deeper, you need to rub the lemon on the bottom of the pan with the salt. This will seem to make a paste.
Just keep squeezing the lemon and sprinkling the salt and rubbing until the bottom of the pan is nice and sparkling clean, and shiny enough to almost see your face in it. My Aunt Dottie taught me this when I was around ten or eleven. I have used the secret trick ever since.
As a matter of fact, I showed it to my Mother as soon as I could after visiting with my Aunt Dottie and Uncle Bobby. She has used the secret trick ever since that as well.