If you put slices of bread in a toaster that are almost too big, you have to push them down at first. If you like to flip them half way, you’ll notice that when they’re hot and half-toasted, they now fit in the toaster no problem - they’ve shrunk. I thought heat expanded things. What’s going on?
WAG:
The water in the bread boils off, and reduces the volume.
There is a difference between physical and chemical changes in things. Heating water and getting steam is a physical change. You can cool steam to get water again. Notice that you can’t untoast toast. That’s because you’re dealing with a chemical change – adding heat in this case causes a reaction that changes the chemical properties of the bread, thus changing the volume.
“WAG:
The water in the bread boils off, and reduces the volume.”
This makes sense to me. I have one of those “toaster-oven” type toasters, and I’ve noticed that when I’m toasting bread, steam collects on inside of the glass door to the toaster.
Also, toast feels a lot dryer than untoasted bread.