# Freezin water in a bottle -- hitting it to form ice

**URL:** <https://boards.straightdope.com/t/freezin-water-in-a-bottle-hitting-it-to-form-ice/180023>\
**Category:** Factual Questions\
**Created:** [June 6, 2003, 6:10am UTC](https://boards.straightdope.com/t/freezin-water-in-a-bottle-hitting-it-to-form-ice/180023 "2003-06-06T06:10:16Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Major\_Kong](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@Major\_Kong](https://boards.straightdope.com/u/Major_Kong)\
**Post date:** [June 6, 2003, 6:10am UTC](https://boards.straightdope.com/t/freezin-water-in-a-bottle-hitting-it-to-form-ice/180023/1 "2003-06-06T06:10:16Z")

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If I put a bottle of water in the freezer it will not appear to be frozen until I hit it then the ice appears. Why is this?

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**Author:** ![tastycorn](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@tastycorn](https://boards.straightdope.com/u/tastycorn)\
**Post date:** [June 6, 2003, 6:37am UTC](https://boards.straightdope.com/t/freezin-water-in-a-bottle-hitting-it-to-form-ice/180023/2 "2003-06-06T06:37:27Z")

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Super cooling. If you keep the water very pure and perfectly still, you can keep ice crystals from forming a few degrees below freezing. If you introduce a foreign particle into the liquid, or create an agitation (whacking the bugger) ice crystals will form at this point the the chain reaction will freeze the rest of the container.