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Author: Subject: Adhesion of distilled water ice to plastic
Sulaiman
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[*] posted on 5-10-2018 at 02:48
Adhesion of distilled water ice to plastic


My refrigerator has inbuilt plastic (I suspect PP) ice trays that distort when twisted to release the ice cubes to a drawer below.
Yesterday I filled the centre of three ice cube trays with distilled water and the other two with tap water.
The two tap water trays deposited their ice cubes when twisted, as normal.
The ice cube tray that was filled with distilled water will not twist or release its ice cubes.
I assume that the distilled water ice is 'stuck' to the plastic whereas tap water ice does not.

WHY ?

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After some minutes at RT the ice became loose and I used it to check the 0oC calibration of my thermometers.
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Foeskes
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[*] posted on 5-10-2018 at 03:22


Maybe the stuff dissolved in water gets pushed to the edge causing there to be water that doesn't freeze and that lubricates the ice.
Distilled water doesn't have much dissolved in it maybe some gasses, so it completely freeze s

[Edited on 5-10-2018 by Foeskes]
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Sulaiman
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[*] posted on 5-10-2018 at 05:44


The freezer is at -18oC,
the tap water has dissolved gasses judging by the bubbles in the ice,
the distilled water ice had few bubbles.

Solids dissolved in water usually get concentrated at the centre of ice as the water freezes from the outside inwards.

The ice cube trays have been used many times without problem,
yet EVERY distilled water ice cube stuck to the tray/mold.
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Tsjerk
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[*] posted on 5-10-2018 at 05:57


I notice the same difference between cooked and uncooked tap water. The cooked water has no gas dissolved and forms a much clearer ice. Maybe because the crystals are more perfect and form a tight fit with the plastic. The uncooked water expels oxygen as gas during freezing which cracks the crystals leaving a white ice. I can imaging the cracking loosens the ice from the plastic.
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Morgan
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[*] posted on 5-10-2018 at 08:03


Here's some other mysteries of tap vs distilled water, maybe some clues/properties/factors would tie in as a food for thought or fuller understanding, once it's all sorted out why distilled water sticks more aggressively to ice trays.
https://www.its.caltech.edu/~atomic/snowcrystals/icespikes/i...

Perhaps distilled water merely forms a finer grain or smoother surface area which locks the cubes creating a better vacuum and allows a more intimate contact/bonding between surfaces.
As an aside, refrigerators are funny how if you decide to get one more thing out of them after just closing the door. The warm introduced air contracts and reopening the door can be significantly harder.
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[*] posted on 5-10-2018 at 08:19


I've noticed PP containers with water adhering to them in an unusual manner when they come out of the dishwasher.

This water is condensation from the drying process which collects in places in the dishwasher, and on the Polyprolylene containers.

It really does 'stick' somewhat more than tap water does when you wash one of these things at the tap.

This may be related.




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Morgan
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[*] posted on 5-10-2018 at 08:40


If you scroll down and read the comments as well, there are more variables to contend with when dealing with ice trays.
https://physics.stackexchange.com/questions/21942/why-do-ice...
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Sulaiman
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[*] posted on 5-10-2018 at 16:31


Morgan, thanks for the links,
... the physics and chemistry of water is just mind-boggling !
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[*] posted on 5-10-2018 at 18:07


Some mention of calcium deposits and other asides ...
"To get clear ice -- with as few air pockets as possible, which can also cause sticking -- use hot or boiling filtered water to make your ice. Replace your ice regularly to reduce the chances of shrinkage, which can lead to increased mineral deposits."
How to Stop Ice in Ice Trays From Sticking
https://www.leaf.tv/articles/how-to-stop-ice-in-ice-trays-fr...

Another who suggests not to stack the trays unless frozen
https://www.chowhound.com/post/ice-cubes-sticking-tray-91749...

"Ice cubes break into pieces because the plastic trays become coated with hard-water mineral deposits (calcium carbonate) that settle into nicks and scratches in the cube compartments and build up over time. Water clings to these deposits as it freezes. To prevent this, buy good-quality plastic trays and don't scrub them with anything abrasive. Clean them occasionally with distilled white vinegar to break down the mineral deposits, then soak them in soapy water to eliminate any odors absorbed from the freezer. Rinse the trays well before refilling."
https://www.goodhousekeeping.com/home/cleaning/tips/a20963/p...

Also I read trays eventually get fissures or micro cracks where at that point it's best just to throw them out.
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