Joe
Years ago I worked at a restaurant, and at the end of the day put aluminum foil over a pan of lasagna. Later, when I brought it out, I noticed a red glow in spots- around black holes in the foil-- everywhere the foil touched the tomato sauce. Turns out that the acid in the tomato sauce was melting the aluminum foil, which was getting left in the food. Yes, it got scooped out, but I stopped using foil after that.