These are copper plant markers which I dipped in ammonia (stinky, stinky!). I filled a smallish container with ammonia and placed a piece of wire (aluminum??) mesh over top. After I dipped the markers directly in the ammonia, I left them on top of the mesh to dry. Not sure if that step was necessary, but I had to find a way for them to dry on both sides. Guess I could have hung them up. Anyway, I'm really pleased with the results!