Why do my ice cubes grow arms?

February 1, 2007 9:12 AM

Why do my ice cubes grow arms?

So, whenever I make ice cubes, at least one or two grow what I call an "arm". See the picture here, where its happened to three! Why would this happen? This only seems to happen when I make them (not my roommate), but I think that's because I tend to fill the tray up to the top with water, and she doesn't.

Does it have something to do with the way ths cold air is blowing over the surface of the water? See here - the air comes out of that vent and blows across the top of the ice. Usually, the arms get broken off when I put another tray on top of it (they're not stackable, so the ones that aren't frozen yet can't have anything on top of it).

Science peeps, please help me solve this mystery! Are my ice cubes trying to escape? (ha) Its been bugging me since I moved in to this apartment 1.5 years ago.

posted by AlisonM to science & nature (15 comments total)

Does this help?

"Why do ice cubes grow spikes?

The short explanation is this: as the ice freezes fast under supercooled conditions, the surface can get covered except for a small hole. Water expands when it freezes. As freezing continues, the expanding ice under the surface forces the remaining water up through the hole and it freezes around the edge forming a hollow spike. Eventually, the whole thing freezes and the spike is left."
posted by routergirl at 9:15 AM on February 1, 2007

Are you using distilled (or perhaps filtered) water?
posted by raf at 9:15 AM on February 1, 2007

I have no idea, but that picture is totally cool.
posted by jacquilynne at 9:15 AM on February 1, 2007

Are you using distilled (or perhaps filtered) water?

Nope, NYC tap water.

routergirl, I can't get to that link right now (no clue why, its timing out), but I don't think the spikes are hollow. The centers do have that cloudy appearance, which I'm assuming means that they have air bubbles, but its not like a tube of air.
posted by AlisonM at 9:21 AM on February 1, 2007

It is kind of a cool photo. I like these, too.
posted by routergirl at 9:21 AM on February 1, 2007

Here's a nifty diagram. Found off of this site. From what I can see, they won't look hollow. See if you can reach that site.
posted by routergirl at 9:24 AM on February 1, 2007

Awesome, routergirl, you rule. Obviously, my google skillz aren't as awesome as I thought they were!
posted by AlisonM at 9:30 AM on February 1, 2007

There's an almost identical diagram on the link I posted above. Check that site out: lots of info.
posted by raf at 10:12 AM on February 1, 2007

Because they're too short to icebox with God?
posted by rob511 at 10:44 AM on February 1, 2007 [4 favorites]

I've got to get mine to do this and stick a camera in the fridge (and a light).
posted by substrate at 11:33 AM on February 1, 2007

I've been meaning to post this same question for a while, as I often get ice-cube stalagmites.

from the article:
That's how it happens and, as the reader's image shows, you can build big spikes of a few centimetres in your own freezer or backyard. However, it is essential to use distilled water or snow melt with no impurities to allow for uniform freezing.

Does this mean I have tap-water with less impurities then usual?
posted by imaswinger at 1:23 PM on February 1, 2007

There's an almost identical diagram on the link I posted above. Check that site out: lots of info.

Sorry, raf, didn't even look at that link, since you mentioned distilled/filtered water. Thanks though - it even looks like they have (almost) the same ice cube trays that I do. Ha! :)
posted by AlisonM at 2:03 PM on February 1, 2007

from the article:
That's how it happens and, as the reader's image shows, you can build big spikes of a few centimetres in your own freezer or backyard. However, it is essential to use distilled water or snow melt with no impurities to allow for uniform freezing.

Does this mean I have tap-water with less impurities then usual?

imaswinger, are you in the NYC area? I've often heard that we have really good/clean tap water (although it could just be a local pride kinda thing). I drink it all the time, and I can't tell the difference from bottled. Also, when out-of-town friends were visiting, I gave them tap water and they said, "oh, this is good water, what brand is it?" Ha! (I live in Astoria, Queens.)

I get at least 1-2 spikes per ice cube tray, and they're always at least 2-3 cm in height.
posted by AlisonM at 2:07 PM on February 1, 2007

Vancouver, but I too use similar blue dollar store trays. Hmmm...
posted by imaswinger at 3:08 PM on February 1, 2007

I also use the blue trays like in the picture, but I've also got some that are a different design/color. The spikes tend to pop up a lot more often in the blue trays.
posted by Clay201 at 2:17 AM on February 2, 2007