How to Spot a Psychopath

A reader writes:

I observed something I consider strange. I had a bottle of white wine which I didn't drink all of, and I decided to freeze the remnants for cooking purposes.

I put a shallow rectangular container in my deep freeze. Into this I put a plastic bag to line the container. Into the bag I poured the wine, which I then left to freeze.

I expected the wine to freeze into a rectangular prism approx 5 by 10 by 1 cm overnight - BUT THIS DIDN'T HAPPEN.

When I opened the freezer the next day, the wine was still liquid! As I watched (over about 20 seconds or so), crystals began to form inside the wine until it began to form an icy slurry.

The wine eventually froze solid after 2-3 days.

My freezer temperature is unknown, but it will freeze meat and water in about six hours.

Why didn't the wine freeze over 12 hours?

Why did it crystallise when it came in contact with the warmer air?

Sorry, it's probably more a Dr Karl question.

Mark

The wine stayed liquid because there were no nucleation points on the plastic with which you lined the tray.

It's possible to superchill water below zero Celsius and have it stay liquid, if there's nothing in contact with the water that provides a seed point from which crystallisation can proceed. This is also how those spiffy sodium acetate heating doodads work.

YouTube is positively packed with people's videos of this phenomenon.

The classic version of the experiment is to super-cool, then tap or shake, a sealed bottle of water:

(This is one of those experiments that's easier to do if you live somewhere where it gets decently cold in winter.)

More advanced experimenters can pour the water out, to make "ropelike peaks":

And, just like the acetate heaters, freezing supercooled water warms up when it freezes:

You can do the trick with beer, too...

...which adds a nifty multiple-starting-point effect, I presume because the nucleation points are little CO2 bubbles popping in and out of existence when you tap the bottle.

It wasn't the warmer air that started the crystallisation going; a speck of dust probably fell into the wine. An ice crystal from one of the shelves of the freezer would have done it, too. Or just agitation of the liquid.

The reason why it took so very long to freeze completely was probably just because there's some alcohol in it. Mixtures of water with any significant amount of alcohol will never freeze in a very satisfying way unless you chill them quite a lot more than the average freezer can manage. Most beer has little enough alcohol in it that its freezing point is only a few degrees below zero, but non-fortified wine already needs about -10 degrees Celsius to freeze, and stronger beverages are lower again.

This is why "frozen vodka" stays liquid, but starts to look sort of oily, as the water in it tries to solidify but the alcohol stays liquid. 40%-alcohol spirits will freeze at about -27 degrees C. Domestic freezers usually only give you about -18 degrees C.