text: experimentation? try this!!! full a plastic bag of water and light your stove or use a lighter and then place it on the bag......... why doesnt the plastic bag melt???? it did! heyyyy.... !  okay, heat transfer is your answer. if the heat is transferred from the bag and absorbed by the water before it can melt the plastic, then the plastic won't melt. same reason why it takes less time to heat an empty saucepan than it would to heat one full of water.