For defrosting for corn snakes just leave the mouse/rat on the windowsill for 4 hours. For Ball pythons I get warm/hot tap water in a bowl and leave the rat there for an hour and then use a hairdryer to make it warm to the touch - has to be the same temp for at least 2-3 seconds then I offer it to her. Only reason I have had a refusal is because of being transferred to the adult tank and bad humidity when I first got her.