How can I tell whether an egg has been hard-boiled, through the shell?

Question

At my workplace, there's a mysterious carton of eggs in the common refrigerator. Nobody I've asked knows whether they're raw or cooked.

Is there a way to tell, without cracking one of the eggs open?

score 23 · Accepted Answer · answered Jul 10 '10 at 17:01

23

Take an egg from the carton and 'spin' it on the work counter. If it spins, it's cooked, if it does anything else, it's not.

answered Jul 10 '10 at 17:01

Pulse

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Seriously? Why does that work? – Andres Jaan Tack Jul 10 '10 at 17:06
The fluid contents of a raw egg move around and prevent the rotational velocity needed to spin. – Rebecca Chernoff Jul 10 '10 at 17:16
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Uncooked eggs will still spin. I find it's better to spin the egg, stop it with your finger, and let go. If it's uncooked, the momentum of the egg sloshing around inside will cause it to start spinning again. If the egg is cooked, it will just wobble around a little. – Michael Mior Jul 10 '10 at 17:20
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To clarify since the post doesn't mention it, this is spinning it on its end, not on its side. – Rebecca Chernoff Jul 10 '10 at 17:28
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@rchern, I can tell when I spin it on its side. Cooked and raw behaves differently. Raw will start spinning slowly with a lag and then faster. Cooked will just spin. – huynhjl Jul 11 '10 at 00:49
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I have experimented with this at home. It's totally right. Both will spin, but the raw egg will spin slowly and awkwardly. Nobody likes awkward food. – Andres Jaan Tack Jul 11 '10 at 12:04
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If you only have a raw or cooked egg, it can be hard to tell if you haven't done it before. If you have one of each, its easy to tell them apart. – Sam Hoice Aug 10 '10 at 05:11

score 3 · Answer 2 · answered Jul 18 '10 at 04:24

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Shake the egg like you would a rattle. If the insides move, raw. If the egg feels solid, cooked.

answered Jul 18 '10 at 04:24

Tim Gilbert

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That's a little hard to feel, don't you think? – Andres Jaan Tack Jul 18 '10 at 23:08

score 0 · Answer 3 · answered Apr 02 '14 at 09:40

The spinning trick is good, but instead of just spinning and then stopping, if you spin it in one direction, stop and try the other direction, a raw egg will spin badly in the opposite direction. The reason is of course the liquid is still going the other way.

How can I tell whether an egg has been hard-boiled, through the shell?

3 Answers3