Question re: physics of ice
We have plastic ice cube trays and I've noticed that when I refill them immediately after emptying them (while the tray is still very cold), the cubes that form stick to the plastic and are very hard to remove, cracking and breaking in the process, whereas if I rinse out the tray and let it warm to room temperature, then refill it and freeze it, the resulting cubes come out cleanly and easily.
Anyone know why this is? Is there some kind of bonding effect between water and cold plastic?
Not something I'd ever heard of before. Interesting. I'll take a TOTAL shot in the dark here:
I suspect the biggest difference would be in terms of how warmer plastic has expanded more than cold plastic. My guess at what's happening: warmer plastic contracts as it cools in the freezer while water actually expands as it freezes - this causes ice cubes that started in a warmer tray to 'settle' a couple times while they're freezing, which in turn loosens them from the sides and bottom of the tray. Ice cubes started in a colder, already contracted plastic tray would do less 'settling' and thus could bond tightly to the plastic in spots, which of course makes them harder to remove.
Really though - I don't know why this happens. Mateo's hypothesis makes decent sense as well.
Conjecture: (chemists please speak up) if you pour a little gin in each compartment before adding water, the water (with a small amount of gin) will then freeze out of the mix first, leaving the remaining gin behind in liquid form which will allow the cube to slide easily out!
Shot in the dark here... but might it have something to do with the insulating properties of plastic?
If your plastic tray is ice-cold when the water is loaded, it might allow the temperature to move faster through the actual tray, versus warm tray which would take a little while to cool down before allowing the cold to move through the tray as effectively. What you might get is that when your ice is freezing from "top down" with a warm tray, the surface freezes first, producing more expansive force on the tray once frozen... whereas when you start with a cold tray, you're getting more even freezing from the size and the top, allowing less pressure to force the expansion of the cube out, and thus the crystals form up.
I wonder how we could test this...