Why do ice cubes stick together?

  1. I've noticed that when I pour myself a glass of ice water the ice cubes will stick together. I put them in my glass as individual cubes, and they seem to melt together where they touch each other. Can anyone explain why this happens? Thanks.
  2. jcsd
  3. Defennder

    Defennder 2,613
    Homework Helper

    I'm guessing it's because applying pressure (due to the weight of the cubes) causes it to melt, but that it refreezes when water is poured into the glass. When it refreezes, it does so in contact with the other cubes so it sticks together.
  4. Andy Resnick

    Andy Resnick 6,142
    Science Advisor
    Education Advisor

    It could also be that a thin layer of water condenses on the cubes from the air and this freezes, sticking the ice cubes together.
  5. Shooting Star

    Shooting Star 1,979
    Homework Helper

    Hi zacsee2000,

    You have to describe in a slightly greater detail as to how you pour the glass of ice water. Once you are saying that the cubes stick together, but then you say that they melt when they touch each other. Do they also stick together side by side? Do you put the water afterwards?

    Defennder has interestingly explained it through regelation, but I doubt if a single ice cube will exert too much of a pressure on a lower one to cause sufficient melting and re-freezing .

    Andy's explanation seems better because the temperature of the ice cubes when you take them out of the icebox (-20 C) is much lower than the room temperature. Water will definitely condense on the boundary, but are the ice cubes cold enough to "freeze" that water again?

    So, a detailed description of what happens when you put them together without water would be helpful. (In the meantime, I can see myself taking too much of iced beer -- well, anything for a good cause...)
  6. It is possible that they just keep close because of surface tension. You would require some force to drag them apart because of water between them, so cubes stick together in their local energy minimum.
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