# Bleaching whites and sunlight

**URL:** <https://boards.straightdope.com/t/bleaching-whites-and-sunlight/107511>\
**Category:** Factual Questions\
**Created:** [May 6, 2002, 8:15am UTC](https://boards.straightdope.com/t/bleaching-whites-and-sunlight/107511 "2002-05-06T08:15:24Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![kambuckta](https://avatars.discourse-cdn.com/v4/letter/k/53a042/32.png) [@kambuckta](https://boards.straightdope.com/u/kambuckta)\
**Post date:** [May 6, 2002, 8:15am UTC](https://boards.straightdope.com/t/bleaching-whites-and-sunlight/107511/1 "2002-05-06T08:15:24Z")

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So why is it that when I’ve soaked my white knickers/tops/boxers in a bleach (sodium hypochlorite) solution, and despite repeated rinsings, when I hang them on the line they invariably turn a brilliant shade of purple.

This is only a temporary phenomenon (thank goodness) and they rapidly return to their original whiteness, but I still wonder why they turn purple in sunlight.

Any musings on the matter here?  
(And don’t give me complicated chemical formulae orright!!)