One position in our freezer seems to make cubes that are very brittle and don’t come out of the iece tray easily or in one piece. Different types of trays make no difference. Is brittle ice water that froze faster? Or is it likely to be colder in that spot of the freezer? I can’t figure out why one spot in the freezer would seem to be colder. What’s the SD on ice?
Ice is a crystalline solid and its physical properties are affected by the rate that it forms, and the composition of the water that makes it (eg, dissolved gasses, other solutes).
If you freeze it quickly, it tends to be less sturdy than slowly frozen ice, that has a chance to form larger crystals with fewer defects and joins. These large crystal ice cubes will be much stronger than ice cubes that formed very rapidly.
From this can I assume that the tray that keeps forming brittle ice cubes is colder than where the other trays sit? Maybe the coils are just outside the freezer wall where the brittle cubes form. That would freeze the water faster but all the cubes would eventually be at pretty much the same temp. Ok, thank you.
You could do an experiment - put a fresh water filled ice tray in the brittle cube spot, and another in a different spot. Then look in on them every 5-10 mins to see which freezes faster. I would be interested in your findings.
And that’s exactly the experiment I did. Using the same type of tray, and using the same amount of water, at the same temperature, I tried it twice. One tray went in the lower left slot, the one that creates the brittle ice. The other went in the upper right slot, one that typically forms good ice, no matter what type of tray I put there. Good ice = ice that comes out easily and doesn’t shatter. In accordance to some information offered above, I anticipated that the lower left ice would freeze faster. And twice, the tray that usually produces the brittle ice was barely frozen after an hour, while the upper right was just about done. So, it appears that feezing slowly works against the formation of “good” ice, contrary to **JoeH2O’**s hypopthesis, while freezing quickly enhances the formation of “good” ice.
slow crystal growth usually makes better crystals. faster can trap gases and cause defects. floating ice can also trap gases. ice made on submerged cold fingers will let the gases release and give a better crystal.
I don’t know about your freezer, but our refrigerator tends to vibrate and shake a lot (relatively subtly, it’s not walking around the kitchen or anything) – that might also drive gasses into our out of water if one of the trays shakes more than the other one.
I’m not sure how you’d test for that: maybe place a single drop of food coloring in each tray (after you’ve placed them in the freezer and let them settle). More vibration might spread the color cloud further, or it might be that brownian motion will completely mix them both before freezing anyway, negating the experiment.
Wait, duh. Is the location that makes the brittle crystals closer to the walls of the freezer? It’s probably the defroster: the ones closes to the wall are being melted and refrozen repeatedly by the defrost cycle.
Oooh, this has possibilities. How often does that mechanism cycle? Several times in an hour? Is that really what happens in a frost free freezer? (Then how does food stay safely frozen?)
Sorry I’m late, the hamsters have taken to randomly unsubscribing me from threads lately. According to this HowStuffWorks article, it cycles about every six hours, and stops when the internal temperature starts getting above 32 degrees. But that seems to be an average: from experience in my old freezer, if you put your hand right over the coil during the defrost cycle, it’s actually hot. My newer refrigerator doesn’t have easy access to the back of the freezer, so I can’t check it.
I think the food safety thing is handled by designing the freezer so that food won’t normally rest right against the heating part (in my new one, this is done by tray design), but this is hardly an area I’m an expert in.