I am thinking this would be fun to use at Christmas time for a gift to a child. Of course would depend on how cold it has to be to bring the color back to the project. But wouldn't it be fun to make a cloth gift bag for a child or maybe even an adult and when they took it outside to go home it would get cold and a secret message would appear. From sound of this it should stay until it was heated by an iron. Does this sound craby? I did nto sleeplong last night so could just be tired.