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lemlurker t1_j934hqv wrote

ice doesnt traditionally remove temperature from your body well as its a solid and needs a phase change to do so so the temperature of the surface is usually around 0c where it contacts the skin.

salt lowers the freexzing temperature so that the ice melts at a lower temp and so when it touches skin it melts at -5 or -10 or colder, now that surface is so far below freezing it can quickly freeze cells in your skin causing ruptures just like burning as your cells arent filled with salt to stop them freezing

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Recipe-Jaded t1_j93fb67 wrote

thank you. In highschool, I asked my physics teacher this question and she said, "because the salt lowers the freezing temperature of the ice". She left it at that, but you filled in the remainder.

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Interesting-Month-56 t1_j93ro1k wrote

Just to add to this, not only is there less no convection with a solid (ice), it has a lower thermal conductivity (though not by much), and the surface area of water in contact with your skin is much higher.

Conductive heat transfer efficiency at an interface will be a function of the total area of contact between the two surfaces. Add in convection, where the heat is rapidly moved away from the skin by mixing of the water and water is a much better coolant than solid ice.

If you further add things like evaporative cooling into the mix, wet skin can be really dangerous.

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EsUnTiro t1_j954zww wrote

> wet skin can be really dangerous

This is such an interesting point, I’m going to go down all kinds of Wikipedia rabbit holes now.

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AnnoyedPanther t1_j96qxqb wrote

As a Sufferer of Secondary Non Focalized Hyperhidrosis I can attest to that. I sweat excessively because of medications I'm on. Unlike most people who will sweat out of focalized point in the body first ie; armpits, forehead, etc. I sweat all over my body at once with minimal effort. My body and the clothes I'm in become soaked. Just the wet skin alone whether it is +30 or -10 degrees triggers cold shock. Your muscles clench, you gasp for air, your heart rate skyrockets, your skin STINGS all over your body and it HURTS. You sweat more because your anxious and it hurts. You just want to curl in a ball and sleep you become so exhausted and quickly. I'ts extremely debilitating.

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