
Anybody know caused these spots?
I promise this is not another dumb cleaning question without searching. I know about BKF, but I won't use it on the shiny side. And I've tried plain vinegar, and good old soap and water. Of course, it's purely cosmetic and in no way affects the performance, but if there's a way to get rid of it I'd use it. [Please ignore the bad edit in the title where I deleted the "what."]