Ice cubes

[hokie66]

A pair of stackable plastic ice cube trays. Identical plastic ones. The cubes in the top one always come out perfectly, while the cubes in the bottom ones stick, and they fracture when being removed. Why is it so?

 

[Artisi]

Gunnar: sorry cannot bring myself to apologise to heathens who drink blended whisky unless of course it is drunk neat under duress.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Skogsgurra]

You understood why. That is OK. But now you also need to understand that.
I have a problem with fundamentalists. Some flexibility makes life much easier.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[Artisi]

Gunnar:
I have been called many things in my days, and they number many, but never a fundamentalists which compared to some of the things I have been labelled with is like water off a ducks back.

Now it seems there is a long list of "fundamentalists" covering all sorts of causes and beliefs, so maybe it is time to start-up a whisky fundamentalist group dedicated to the believes in single malt, so - if you would like to mend your ways, become a born-again single malt user and return back to the true path you can join in as a founding member. The offer is only open for 24 hours and you get a box of steak-knives at no extra cost for joining.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[hokie66]

Progress report on my ice cubes. Thanks for all the feedback. A few comments deserve mention:

1. VE1BLL suggested raising the freezer. I don't understand that one, so haven't tried it.
2. The quality of the ice wasn't in question, so I haven't tried distilled water.
3. Not getting involved in the whisky/whiskey fundamentalism...that's been done a lot.
4. We did have an icemaker fridge at one time, but after it almost burnt the house down, I don't want another.

I think the answer is related to the other suggestions, but will just tell you what I found in my simple tests, in which I froze cubes with the trays in four different orientations. Trays sitting on glass shelves in freezer compartment of side-by-side fridge.

1. Both trays filled, bottom tray cubes stick and crack, top tray cubes pop out perfectly.
2. Bottom tray filled, top tray empty, cubes in bottom tray stick and crack.
3. Bottom tray empty, top tray filled, cubes in top tray pop out perfectly.
4. Both trays (or one tray) filled, but not stacked, cubes pop out almost perfectly.

So it looks to me like the bottom tray cubes stick and crack due to being covered, while the uncovered trays produce good cubes. So it looks like unimpeded access by air to the top is the key. I will leave the technical reasons to you smart guys. It would be interesting to see whether someone else can repeat my observations.

 

[BigInch]

It's not air, it's the freezing air. Freezing air temperatures do not come in contact with the liquid surfaces in the bottom tray.

Independent events are seldomly independent.

 

[hokie66]

But these trays don't seal against each other. All around the edges, the cold air can circulate through the bottom tray.

 

[Skogsgurra]

Artisi
That's an offer I probably can't refuse.

Actually, I have a friend with a full wall book-shelf filled with single malt bottles. I consider him an authority in the noble art of drinking distilled spirits. I visited him a couple of nights ago and we tried out a Japanese whisky. No smoke at all, it was like a mild cognac. Oak sherry vat. Single malt. Vanilla and honey character.

After that we got soaked with an old Grouse. Horror? Or just a pleasant way to spend an evening? I think the latter. We also ran a few of his steam engines. A man of many qualities.

And what about the Nippon whisky? Can that be drunk - in your opinion?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[KENAT]

I believe to the Fundamentalists Skogs if it don't come from Scotland it aint Whisky it's Whiskey.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[Skogsgurra]

It don't mean a thing if it ain't got that swing? Is that the gist of it, Kenat?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[btrueblood]

Doo wop doo wop doo wop. Thanks Gunnar, now I've got that song stuck in my head. Could be worse, I suppose.

 

[zdas04]

Back to the question (guys, we've done the Scotch theological discussion, if you want to do it again please start a new thread so I can never open it).

Hokie,
Your experimental data seems to indicate that the problem is related to the bottom of the freezer. I'd put down a silicone hot pad and do the stacked experiment again and see what the bottom looks like when it is not in direct contact with the bottom of the freezer.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[hokie66]

David, the glass shelf is in the top half of the freezer, but maybe it is the contact with the shelf, although when there is nothing on top of the tray, the cubes are fine. Will try the pad and report back.

 

[zdas04]

I'm wondering if the weight of the second tray is enough to improve the contact with the shelf enough to change something. That's why you do experiments.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[BigInch]

hokie, you can't "seal" temperature. Slow it down (decrease the thermal gradient), yes, temporarily. You still have the same (unstable) thermal gradient, cool temperature on top, warmer on bottom. The stable gradient exists within the bottom tray.

Got some baby food jars and food coloring?

http://www.youtube.com/watch?v=uSFSNTI67wc

http://education.nationalgeographic.com/education/media/lake-turnover/?ar_a=1

Independent events are seldomly independent.

 

[btrueblood]

I'd say y'all are guilty of what we yell at the newbies for - 3 days in and still no pictures of the trays, and what they look like stacked/unstacked. Not that with that information, I'd be able to say why the bottom tray gives sticky cubes.

 

[Compositepro]

Perhaps the answer lies in why ice does not does not stick to the upper tray, since ice tends to stick tenaciously to most surfaces, including the bottom tray. My hypothesis is that in the upper tray ice clearly forms on the upper surface of the water first and progressively freezes downward. As water freezes it expands and this creates a pressure which lifts and releases the cube from the tray. Thus most of the cube is already released when freezing is complete. You might think that most bodies of water freeze this way, which is true. But, water sprayed or rained onto a cold surface stick tenaciously because it freezes at the contact surface first.

The bottom tray cannot freeze on top first, because its top surface is in contact with the bottom of the top tray. The bottom of the top tray is the last point to freeze. Convection currents are trapped within each tray. So the bottom tray freezes from the walls inward and the expansion of the ice does not create any pressure to release the ice.

 

[BigInch]

Hummmm. Yes. I think I can agree with that.



Independent events are seldomly independent.