I keep mine in a tupperware container in the fridge for a couple of months. I set it out in the morning when we are going to be inside and use it and within a couple of hours it's warm enough to play with. Then after a few months I have the children use it up as a craft and we let it harden. One time we made it into volcanoes and another time we cut it into shapes and put a hole in the top to thread a yarn through so it could be a hanging decoration.