Hello! I just bought (another) copper pan on ebay... a little tin-lined copper saucepan to be exact. I just cooked my first dish in it, a little tomato and butter sauce, and after rinsing the pan I noticed some reddish-brown staining. I'm attaching a photo. I think, based on other posts here, that this is just the tin getting stained. But since it's a used pot and I've never cooked in a tin-lined pan before, I wanted to be sure the lining wasn't worn away. Would love any thoughts. I'm attaching a before and after photo, as well as a picture of the pan itself for reference.
I'm also attaching a picture of where the pan's handle joins the body, because there seems to be some white stuff along the border. I'm curious if anyone knows what this is. Not really worried about cleaning it - just curious and would love to learn what it is.
Thanks for any input!