While dying Easter eggs with the kids I noticed both boxes of dye had the same instruction. “Boil clean eggs in a glass, ceramic, or stainless steel pot. Do not use iron or aluminum cookware”.
Why not? What difference does it make?
http://home.aristotle.net/easter/fun/crafts/spinach.html
Please note that can does not mean will.
It turns the white of the egg black (well, gray) and the yolk greenish. It also changes the flavor.
That’s caused by overboiling, not pot composition. If you bring them to boil and then cover and remove from the heat, they’ll cook in about 15 minutes without greenish yolks. Plus the whites come out softer - overheating turns them rubbery.
I think it’s a reactive versus unreactive thing. Iron and aluminum are the former while steel, glass, and ceramic are the later. I do quite a bit of canning/pickling and using a reactive pot with acidic ingredients is a no-no, you can get a strange tasting or looking result. (On a slight tangent-vinegar and too-old garlic creates an interesting green color.)