I've been using Wilton flower nails as heating cores. I notice that the stems appear to be discolored in spots. LIke the metal is dark grey. Is this a normal occurrence? When that happened with some Wilton tips, I just threw them away. Which I plan to do with these, as soon as I make the next trip to Michaels. In the meantime, are they ok to use?

It's just the metal reacting to the heat. No problem using them as long as it is not rusty.

I think this happens a lot. I soak both flowers nails and tips in a bowl of Coca-Cola and they look a lot better!