JSB & CY-
I've frozen a few things in glass over the years in the freezer and outside.....jsut a curious kid with an understanding dad.
My comment is...if the glass has any importance, dont do it.
Sometimes they break but most of the time they don't. I think it has to do with the shape of the containter AND with how (from where) it starts to freeze. My theory is, if the top froze first, it created a "cap" and didnt allow the ice to grow in height.
CY- When water freezes it expansion in all directions. Just like when a homogeneous material (like a block of metal) is subject to unifrom heating, it grows in all three axes.
But lets not get started on a discussion of what happens when a metal washer is heated.... :)
cheers Bob
+++I don't intentionaly do it, but as I remember, if you freeze water in a glass (open or closed), it can break. Probably determined by the strength of the glass.
Jim