# Why does epoxy cure slower if spread thin?

**URL:** <https://boards.straightdope.com/t/why-does-epoxy-cure-slower-if-spread-thin/621803>\
**Category:** Factual Questions\
**Created:** [May 13, 2012, 9:20pm UTC](https://boards.straightdope.com/t/why-does-epoxy-cure-slower-if-spread-thin/621803 "2012-05-13T21:20:32Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![nitromethane](https://avatars.discourse-cdn.com/v4/letter/n/ee59a6/32.png) [@nitromethane](https://boards.straightdope.com/u/nitromethane)\
**Post date:** [May 13, 2012, 9:20pm UTC](https://boards.straightdope.com/t/why-does-epoxy-cure-slower-if-spread-thin/621803/1 "2012-05-13T21:20:32Z")

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Why does epoxy, if spread thin, take longer to set? I noticed when I mixed a batch today, the stuff I had in the mixing container got hot and set quicker than the thin spread in a fillet I had on my model rocket’s fins.

Thanks in advance…

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**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\
**Post date:** [May 13, 2012, 9:52pm UTC](https://boards.straightdope.com/t/why-does-epoxy-cure-slower-if-spread-thin/621803/2 "2012-05-13T21:52:54Z")

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many chemical reactions occur faster with a rise in temperature. chemical reactions can also give off heat as they occur.

the heat in the fillet is lost faster than the heat in mixing container.