Eli5 why do people say to wash dishes or your hands in warm water when cold slows down bacteria growth?
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It’s a physics assist as opposed to a germicidal assist; friction does the cleaning, and water that loosens stuff up (warm) is better.
Neither cold not warm are great at killing bacteria. Greases though, are at the temperature border between solid and liquid (the difference between grease and oil is basically melting point above or below room temp) so warmer will lead to release of a lot more greases, and many soaps also work better at warmer temperatures for much the same reason (soaps are fatty molecules). Oil and grease trap particles (and bacteria) and serve as a food source for bacteria, so eliminating superficial grease is the objective of cleaning and the reason to use warmer water as a general thing.
Many modern soap formulations are designed to work well at lower temperatures so they function well in cold water. It took a bit of work finding detergents that do work well at lower temps though (like cold water detergents for clothes).
Neither cold not warm are great at killing bacteria. Greases though, are at the temperature border between solid and liquid (the difference between grease and oil is basically melting point above or below room temp) so warmer will lead to release of a lot more greases, and many soaps also work better at warmer temperatures for much the same reason (soaps are fatty molecules). Oil and grease trap particles (and bacteria) and serve as a food source for bacteria, so eliminating superficial grease is the objective of cleaning and the reason to use warmer water as a general thing.
Many modern soap formulations are designed to work well at lower temperatures so they function well in cold water. It took a bit of work finding detergents that do work well at lower temps though (like cold water detergents for clothes).
Neither cold not warm are great at killing bacteria. Greases though, are at the temperature border between solid and liquid (the difference between grease and oil is basically melting point above or below room temp) so warmer will lead to release of a lot more greases, and many soaps also work better at warmer temperatures for much the same reason (soaps are fatty molecules). Oil and grease trap particles (and bacteria) and serve as a food source for bacteria, so eliminating superficial grease is the objective of cleaning and the reason to use warmer water as a general thing.
Many modern soap formulations are designed to work well at lower temperatures so they function well in cold water. It took a bit of work finding detergents that do work well at lower temps though (like cold water detergents for clothes).
If I had to make an educated guess, it’s because soap is a special type of substance called an “emulsifier,” which means it sticks to both oil and water (which normally won’t attach to each other). This is how it cleans oily dirty goo off you using the running water. And probably that particular chemical reaction happens more easily in the warm than in cold.
Or perhaps it’s just that warm water is more comfortable on the hands.
If I had to make an educated guess, it’s because soap is a special type of substance called an “emulsifier,” which means it sticks to both oil and water (which normally won’t attach to each other). This is how it cleans oily dirty goo off you using the running water. And probably that particular chemical reaction happens more easily in the warm than in cold.
Or perhaps it’s just that warm water is more comfortable on the hands.
It’s because bacteria are tiny creatures that are cold-blooded, so they thrive in warm environments!
If I had to make an educated guess, it’s because soap is a special type of substance called an “emulsifier,” which means it sticks to both oil and water (which normally won’t attach to each other). This is how it cleans oily dirty goo off you using the running water. And probably that particular chemical reaction happens more easily in the warm than in cold.
Or perhaps it’s just that warm water is more comfortable on the hands.
It’s because bacteria are tiny creatures that are cold-blooded, so they thrive in warm environments!
If you’re trying to get bacteria to grow, then you should definitely use cold water! Bacteria love a chilly environment.
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