Maria, I use Bar Keeper's Friend for the interior of my SS pots/pans and copper fry pan too with
great results. It's like a little dab (paste & water) and a gentle swirl-scrub of it will take away any scorched/hardened spots and so on.
I'm reading the label of BKF and it says:
"HOUSEHOLD: Cleans fiberglass, stainless steel, imitation marble, and porcelain sinks, tubs, tile, glass-ceramic, cooktops, chrome, copper and brass."
I have not used it on my copper or brass, but note that copper and brass is at the bottom of the list. I'm wary of using it on my copper and brass simply because I think it's a less abrasive form of Comet Cleanser.
I "think" BKF might be too abrasive for copper or brass. I may be wrong.