For ten years I have had two excellent "Emeril" cookie sheets, heavy duty, crosshatch design, were expensive. I have loved them---they clean easily and cookies bake evenly and never burn. This morning I used Ajax cleanser on one of them and now every time I wipe it with a cloth or paper towel I get just reams of pitch black stuff coming off it---am afraid to use it. They never did this before. Can you not clean aluminum with Ajax? What did I do? Can I remedy the situation?