I am new to the forum and had a question about sheet pans. I have been using two different sheet pans to make Pizza Bianca (Cooks Illustrated), the recipe involves a wet dough poured onto a well oiled baking sheet and cooked on a baking stone at 400 degrees. It is very good; however, when I wash the pans it is like the pan is dissolving into the dishwater leaving the water a charcoal color. The more I scrub the more charcoal colored material is removed from the pan. I don’t know what the pans are made of, but they are not stainless, perhaps aluminum. Anyone have any idea what the material is and if it’s harmful? I am making this pizza a lot and I don’t want my family ingesting something that s not good for them.