Andy, it's been months since we've heard anything. I thought of your conundrum while cleaning marks off of our kitchen floor. I know where ours come from - Himself's black-bottomed bedroom slippers. However, have you or your SO figured out where your black marks came from? Are they still happening? Update, please.
"Cooking is the art of adjustment." ~~~Jacques Pépin
“A party without cake is just a meeting.” ~Julia Child
"A dream is a festival of lights within your mind." ~~~ Joan Walsh Anglund