I was recently told that having a metal spoon in the coffee would heat the cup of coffee up, and that it would be hotter if I stirred because of the conductivity of the metal in the spoon. This seems counter intuitive because wouldn't the spoon radiate the heat out from the handle?

He provided an answer I didn't quite understand (he's an engineer), but I have to check here.

Is this true?

  • 3
    Related (top voted) question on Physics.SE: physics.stackexchange.com/questions/5265/…
    – Will
    Jul 15, 2016 at 14:44
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    Is this type of question actually more appropriate for a technical site? it's not so much about "proving/disproving a claim made somewhere [really, in the media]" as just "me and my buddy were discussing X technical issue".
    – Fattie
    Jul 15, 2016 at 14:54
  • @joe many people believe this claim. So, it is notable and on-topic here. It might get a better answer somewhere else, but it can still be asked here.
    – user30557
    Jul 15, 2016 at 15:06
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    @dawn - fair enough, if it is a "broadly believed claim", then you're quite right it's good on here. Thanks for that
    – Fattie
    Jul 15, 2016 at 15:12
  • @Will Actually, that should count as a reference to make an answer. Jul 15, 2016 at 16:20

1 Answer 1


The spoon's conductivity would only heat the coffee if you were holding the spoon with a super-hot hand. Assuming the spoon (and your hand) are both cooler than the coffee, they will both conduct heat away from the liquid, causing the coffee to cool a teensy bit more quickly.

Stirring the liquid should logically only speed the process.

Believe it or not, a fellow nerd on physics.stackexchange.com conducted an experiment on this very issue and published the results, which confirm my hypothesis:



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