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Watch Water Freeze

Watch Water Freeze
Freezing water forms a spiky kaleidoscope of colorful crystals.

Ordinarily, water freezes too slowly to be appreciated. Here, polarized light and an ultra cold slab let you watch water crystalize rapidly in real time. The colorful mosaic of ice that forms is different every time.

Close up of hands touching the Watch Water Freeze exhibit at the Exploratorium.
Museum visitors looking at the Watch Water Freeze exhibit at the Exploratorium.
What’s going on?
You can see colors in this ice thanks to special light filters called polarizers. The various colors appear for two reasons: slightly different thicknesses in the ice, and tiny stresses that develop within the ice as the crystals form and collide. Chilled by coolant from below, the glass is so cold that when you squirt water on it, the water freezes into crystals.
Going further

On some lucky occasions, you may witness a sudden, abrupt freezing of all the water on the slab. Ice crystals needs a surface or seed crystal on which to form. If none are present, the water becomes supercooled—cooled to well below the freezing point—until a seed crystal forms and ice suddenly spreads.

Charles Sowers and his Watch Water Freeze Exhibit