# Pop question

**URL:** <https://boards.straightdope.com/t/pop-question/20092>\
**Category:** Factual Questions\
**Created:** [May 21, 2000, 5:03am UTC](https://boards.straightdope.com/t/pop-question/20092 "2000-05-21T05:03:19Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![SpecialK](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@SpecialK](https://boards.straightdope.com/u/SpecialK)\
**Post date:** [May 21, 2000, 5:03am UTC](https://boards.straightdope.com/t/pop-question/20092/1 "2000-05-21T05:03:19Z")

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Why is it that pepsi and other forms of soda foam up when you pour them, and drinks like 7up do not?

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**Author:** ![Homer](https://avatars.discourse-cdn.com/v4/letter/h/df788c/32.png) [@Homer](https://boards.straightdope.com/u/Homer)\
**Post date:** [May 21, 2000, 5:50am UTC](https://boards.straightdope.com/t/pop-question/20092/2 "2000-05-21T05:50:54Z")

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WAG, but I think it has to do with the nature of the flavoring. IMO, pepsi, coke, dr pepper, root beer, all forms of darker sodas are heavier than the clear and yellow varieties. The heavier syrups form thicker bubbles that stay around longer, whereas the lighter sodas form thinner, weaker bubbles that pop pretty quickly.

–Tim