Why is 70% alcohol solution a much better disinfectant than a 90% alcohol concentration? Wouldn’t a higher concentration mean better?
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As I once posted:
70% alcohol has 30% water, and that water is necessary for the alcohol to interact at all with the cells it’s killing.
It’s like cooking pancakes. You know how when your pan is really hot and you put in pancake batter, it cooks the outside really fast? And then you can flip it, but it does the same thing to the other side and the middle doesn’t cook very well? 90% alcohol is like that. It doesn’t penetrate well into cells or clumps of microbes because it just fries everything it touches on the outside. The 70% alcohol is like cooking on medium heat with a moderately hot pan. It contacts the outside, too, but the water helps it penetrate to cook the inside (denature proteins deeper) as well.
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