Why 70% ethanol & not 95% as disinfectant? - (Jun/12/2006 )

because you need also water to denature the proteins, enough water but not too much, not to dilute ethanol. That's why 70% is the best concentration to use, and it is better than 90%.

also 95% ethanol evaporates very quickly at room temp, thus 70% is more effective

It also saves your ethanol

ha ha ha........

It depends on what you are using it for...

If you are using it for cleaning benched etc, then the 70% is so that there is a dehydration effect on the bacteria, thus killing the bacteria.

70% in DNA preps, for example, is used to keep the DNA as a precipitate, but still allow most of the proteins and salts to go into solution, so that the DNA is clean at the end.