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I always thought the purpose of hot water was to improve the reaction between the soap and the oils on your hands. Use cold water, and the oil thickens, which
by ianferrel 13y ago
I always thought the purpose of hot water was to improve the reaction between the soap and the oils on your hands.
Use cold water, and the oil thickens, which makes it harder to emulsify, and less likely to get washed away in the water. Use hot water, and the oils are easier to wash away. Oils can trap dirt and bacteria, so washing them away makes your hands cleaner.
There's a telling quote from the article that makes me think they're not really studying what they should: " Even water as cold as 40°F (4.4°C) appeared to reduce bacteria as well as hotter water, if hands were scrubbed, rinsed, and dried properly."
But how do they fare when hands aren't scrubbed rinsed and dried properly, and does the average person scrub, rinse, and dry their hands properly? More importantly, are they more likely to do so if the water is pleasantly warm? If hot water helps in the actual common case, then it's still important.
- stefantalpalaru 13y agoYou're right. They also think that the purpose of washing one's hands is killing germs instead of removing them from the skin.
- steven2012 13y agoI'm in my 40s, but I only learned in the last ~10 years that soap didn't kill bacteria, but only helped remove bacteria that was stuck in the oil in your hands. My sister, who is in the medical field, told me this and at first I refused to believe her because the idea had been with me basically my entire life.
- bluekitten 13y agoDo hand sanitizers work differently then? You don't need to use water with those, just applying them is supposed to do the trick. I think some have alcohol that kills the germs.