# Bleach and Flour Chemical Reaction

**URL:** <https://boards.straightdope.com/t/bleach-and-flour-chemical-reaction/294231>\
**Category:** Factual Questions\
**Created:** [March 12, 2005, 8:13pm UTC](https://boards.straightdope.com/t/bleach-and-flour-chemical-reaction/294231 "2005-03-12T20:13:12Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![rayray5884](https://avatars.discourse-cdn.com/v4/letter/r/57b2e6/32.png) [@rayray5884](https://boards.straightdope.com/u/rayray5884)\
**Post date:** [March 12, 2005, 8:13pm UTC](https://boards.straightdope.com/t/bleach-and-flour-chemical-reaction/294231/1 "2005-03-12T20:13:12Z")

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My dad was trying to come up with his own bleach paste mix and decided that mixing flour with bleach would be safe and get the job done. Only problem was that the mixture quickly started to heat up and he could no longer hold the container that it was in. Can anyone explain why this reaction between bleach and flour? Thanks in advance!

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**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\
**Post date:** [March 12, 2005, 10:19pm UTC](https://boards.straightdope.com/t/bleach-and-flour-chemical-reaction/294231/2 "2005-03-12T22:19:32Z")

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You didn’t say whether you are using a peroxide bleach or chlorine bleach. However both are oxidizing agents and there are plenty of sites on starch to be oxidised, releasing heat

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**Author:** ![Busy\_Scissors](https://avatars.discourse-cdn.com/v4/letter/b/d78d45/32.png) [@Busy\_Scissors](https://boards.straightdope.com/u/Busy_Scissors)\
**Post date:** [March 12, 2005, 10:22pm UTC](https://boards.straightdope.com/t/bleach-and-flour-chemical-reaction/294231/3 "2005-03-12T22:22:39Z")

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> [@rayray5884](#):
>
> My dad was trying to come up with his own bleach paste mix and decided that mixing flour with bleach would be safe and get the job done. Only problem was that the mixture quickly started to heat up and he could no longer hold the container that it was in. Can anyone explain why this reaction between bleach and flour? Thanks in advance!

I can’t say for sure whats going on, but you’re basically mixing an aqueous solution of an oxidising agent (the bleach) with an organic substance that is easily oxidised (the flour). The result will be an exothermic reaction, and its possible that you’re generating toxic gases as by-products. The reason its hard to be precise is that the flour is a mixture of all sorts of complex carbohydrates, so it would be difficult to point to one particular molecule and say that you’re oxidising it.

I guess it doesn’t need saying that it is a generally poor idea to mix househould bleach with just about anything. As far as laboratory chemicals go, it is a mild, easily controlled reagent. As far as the bottles under your sink go, it is one of the most toxic and reactive substances in your house.

What do you need a bleach paste for?

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**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\
**Post date:** [March 12, 2005, 10:38pm UTC](https://boards.straightdope.com/t/bleach-and-flour-chemical-reaction/294231/4 "2005-03-12T22:38:45Z")

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Lord-‘a’-mercy, you make bleach paste with bleach and _baking soda_, not _flour_. I don’t know why the reaction would build up so much heat – flour is bleached routinely – but that’s definitely not something you want to clean with.