[Maria T-M (OP)]

I always tear up a lot when I'm dicing onions or garlic, and wearing glasses doesn't really help that much. I know some people wear kitchen goggles for this, but I heard somewhere that taking a gulp of water and holding it in your mouth while you chop the onions prevents the tearing up. I've tried it multiple times, and it's always worked. One time, I accidentally forgot and swallowed the water midway through the chopping, and my eyes got irritated and teary right away.

Any ideas why this works? It seems to me that if some chemical in the onion is irritating my eyes, it should still do so even when I have a mouthful of water, so does that mean my eyes are getting irritated without being able to produce tears as a coping mechanism? But shouldn't my eyes still sting then? So many questions!

[evan_au]

I can't see how holding water in your mouth should help.
But one I can understand is cutting onions in a pot of water. The water dissolves the irritating chemicals so they aren't aerosolized*, and get in your eyes.

*aerosolized: A COVIDism.

[Petrochemicals]

Maybe it encourages moisture release in the eyes before irritation and not after.

Perhaps it's the angle you hold your head. Chop onions at arms length .

Not having tried it myself I cannot say.

[Bored chemist]

*aerosolized: A COVIDism.

What?

For what it's worth, my best guess is the effect is psychosomatic.

[Maria T-M (OP)]

Maybe it encourages moisture release in the eyes before irritation and not after.

Perhaps it's the angle you hold your head. Chop onions at arms length .

Thanks for offering up these potential explanations, but unfortunately, they don't fit my experience. My eyes don't start watering preemptively when I hold the water in my mouth. As far as chopping at arms' length, I tried that before the water "life hack" and it was too awkward, plus my counter is a bit narrow. So I chop normally now.

[Maria T-M (OP)]

For what it's worth, my best guess is the effect is psychosomatic.

Hmm, could be, I suppose. Hard to test, unless I find an unsuspecting subject and ask them to do this random thing (chop onions while holding a mouthful of water) without explaining why. 

[Petrochemicals]

Maybe it encourages moisture release in the eyes before irritation and not after.

Perhaps it's the angle you hold your head. Chop onions at arms length .

Thanks for offering up these potential explanations, but unfortunately, they don't fit my experience. My eyes don't start watering preemptively when I hold the water in my mouth. As far as chopping at arms' length, I tried that before the water "life hack" and it was too awkward, plus my counter is a bit narrow. So I chop normally now.

How about the head angle ?   It could just be different strength onions, how diligently did you Cary out the experiment ?

[Maria T-M (OP)]

How about the head angle ?   It could just be different strength onions, how diligently did you Cary out the experiment ?

Not that diligently, but now I'm tempted to go at it with a fully randomized, double-blind experimental design 

I suppose the head angle might be a bit different just from having a mouth full of water... I guess I could test this by having e.g. a mouthful of food. The life hack was specifically about water for some reason.

I will have to report back the next time I chop onions.

[Zer0]

Hello Maria & Welcome to TNS!
🙏

Donno how or why water works.

I had heard of a similar but different method.

Hence i placed a green chilli on my head, n chopped away without tears.

Ps - Perhaps bloated chubby cheeks   divert the enzyme vapour flow away from the eyes.