Recently I did a saute in grape seed oil and butter of breaded skinless chicken breasts in my heavy (2mm) copper pan over easy heat. Added lemon juice at end of saute. Great chicken golden and juicy.

To clean the pan I soaked in hot water and soap then used Barkeepers Friend to clean tin lining and exterior copper. It looked like large areas of the tin lining on the bottom had disolved, leaving copper showing through. This was a fairly new pan with what looked like a good tin coating and I've sauted in it many times. No scratches in the tin.

Did the lemon juice dissolve the tin or what?