# Plastic Bottle Bottoms

**URL:** <https://boards.straightdope.com/t/plastic-bottle-bottoms/102170>\
**Category:** Factual Questions\
**Created:** [April 6, 2002, 1:49pm UTC](https://boards.straightdope.com/t/plastic-bottle-bottoms/102170 "2002-04-06T13:49:12Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![festiva76](https://avatars.discourse-cdn.com/v4/letter/f/8e8cbc/32.png) [@festiva76](https://boards.straightdope.com/u/festiva76)\
**Post date:** [April 6, 2002, 1:49pm UTC](https://boards.straightdope.com/t/plastic-bottle-bottoms/102170/1 "2002-04-06T13:49:12Z")

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Quick everyone… Look at the bottom of nearly any plastic bottle (sans soft drink bottles), and you may find at least one indention on the bottom. They appear to be sloping, similiar to a swimming pool. Anyone have a clue as to what these are called and why they exist peacefully amongst both us and smoother-bottomed plastic bottles? Please forgive if this has already been asked in a previous post.

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**Author:** ![cagiva650](https://avatars.discourse-cdn.com/v4/letter/c/da6949/32.png) [@cagiva650](https://boards.straightdope.com/u/cagiva650)\
**Post date:** [April 6, 2002, 2:21pm UTC](https://boards.straightdope.com/t/plastic-bottle-bottoms/102170/2 "2002-04-06T14:21:01Z")

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Maybe it matches up with an outie at the bottling plant. Something the bottle stands on whilst it’s filled up with the sweet colorful concoction of SODAPOP

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**Author:** ![Weeks](https://avatars.discourse-cdn.com/v4/letter/w/bbce88/32.png) [@Weeks](https://boards.straightdope.com/u/Weeks)\
**Post date:** [April 6, 2002, 2:55pm UTC](https://boards.straightdope.com/t/plastic-bottle-bottoms/102170/3 "2002-04-06T14:55:43Z")

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a protruberance (sp.?) fits into it to keep the bottle from turning against the cap being screwed on.