# Microwave makes my tea/coffee foam - why?

**URL:** <https://boards.straightdope.com/t/microwave-makes-my-tea-coffee-foam-why/402742>\
**Category:** Factual Questions\
**Created:** [May 4, 2007, 2:39pm UTC](https://boards.straightdope.com/t/microwave-makes-my-tea-coffee-foam-why/402742 "2007-05-04T14:39:30Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Swallowed\_My\_Cellphone](https://avatars.discourse-cdn.com/v4/letter/s/9d8465/32.png) [@Swallowed\_My\_Cellphone](https://boards.straightdope.com/u/Swallowed_My_Cellphone)\
**Post date:** [May 4, 2007, 2:39pm UTC](https://boards.straightdope.com/t/microwave-makes-my-tea-coffee-foam-why/402742/1 "2007-05-04T14:39:30Z")

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So, Idiot Co-worker comes into the kitchen, finds a full kettle of boiling water. Dumps the freshly boiled water down the drain because “He doesn’t know how long it’s been sitting there and doesn’t want lead poisoning.” :smack: This is par for the course in this office.

Since my department has the heaviest workload in the office and I really just can’t stand over and guard the kettle for the “only 8 minutes to boil!” (I really can’t), I’ve given up and I stick a mug of water in the microwave.

I’ve noticed, when I take my hot mug of microwaved water back to my desk and thrown in either a tea bag or instant coffee, it’s foamy. This doesn’t happen on the rarest occasions when I actually get the water I boiled in the kettle. What is happening?

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**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\
**Post date:** [May 4, 2007, 3:08pm UTC](https://boards.straightdope.com/t/microwave-makes-my-tea-coffee-foam-why/402742/2 "2007-05-04T15:08:53Z")

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> **[Why does Sweet ‘n Low make microwaved water fizz so strangely?](https://www.straightdope.com/21341860/why-does-sweet-n-low-make-microwaved-water-fizz-so-strangely)**

This is asked often in these forums, but nothing appears in a board search for me today. I got this link using google search.

The key word is nucleation.

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**Author:** ![Swallowed\_My\_Cellphone](https://avatars.discourse-cdn.com/v4/letter/s/9d8465/32.png) [@Swallowed\_My\_Cellphone](https://boards.straightdope.com/u/Swallowed_My_Cellphone)\
**Post date:** [May 4, 2007, 3:52pm UTC](https://boards.straightdope.com/t/microwave-makes-my-tea-coffee-foam-why/402742/3 "2007-05-04T15:52:42Z")

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Ah, thanks.