# Anti-Condensation Cups?

**URL:** <https://boards.straightdope.com/t/anti-condensation-cups/23984>\
**Category:** Factual Questions\
**Created:** [June 29, 2000, 7:00am UTC](https://boards.straightdope.com/t/anti-condensation-cups/23984 "2000-06-29T07:00:07Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![chief](https://avatars.discourse-cdn.com/v4/letter/c/df788c/32.png) [@chief](https://boards.straightdope.com/u/chief)\
**Post date:** [June 29, 2000, 7:00am UTC](https://boards.straightdope.com/t/anti-condensation-cups/23984/1 "2000-06-29T07:00:07Z")

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My friend told me about these cups at Jamba Juice that he saw that did not condense water on the outside when there was a very cold beverage inside.

Does anyone know how it works?

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**Author:** ![tcburnett](https://avatars.discourse-cdn.com/v4/letter/t/c5a1d2/32.png) [@tcburnett](https://boards.straightdope.com/u/tcburnett)\
**Post date:** [June 29, 2000, 7:07am UTC](https://boards.straightdope.com/t/anti-condensation-cups/23984/2 "2000-06-29T07:07:33Z")

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The cups have an inner and an outer surface separated by an air gap.

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**Author:** ![TNTruth](https://avatars.discourse-cdn.com/v4/letter/t/d9b06d/32.png) [@TNTruth](https://boards.straightdope.com/u/TNTruth)\
**Post date:** [June 29, 2000, 2:37pm UTC](https://boards.straightdope.com/t/anti-condensation-cups/23984/3 "2000-06-29T14:37:53Z")

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Or a vacuum gap, a la a thermos bottle.

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**Author:** ![charizard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/charizard/32/4166_2.png) [@charizard](https://boards.straightdope.com/u/charizard)\
**Post date:** [June 29, 2000, 2:49pm UTC](https://boards.straightdope.com/t/anti-condensation-cups/23984/4 "2000-06-29T14:49:51Z")

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Condensation forms on any cool surface. The water vapor in the (warmer) air turns back into a liquid just because it’s now below the dew point for the atmospheric condition.

So the basic answer is that any sort of “anti-condensation” cup is highly insulated, so that the coolness of the beverage isn’t transmitted to the surface of the cup. The insualtor could be air, or a vacuum, or some other insulating material.