To effectively disinfect tools, ethyl alcohol must be at least what percentage?

To effectively disinfect tools, ethyl alcohol must be at least 70% concentration. This percentage is crucial because it allows the alcohol to penetrate the cell membranes of microorganisms efficiently. At this concentration, ethyl alcohol is able to denature proteins and disrupt cellular functions, thereby effectively killing bacteria, viruses, and fungi.

Lower concentrations, such as 50% or even 60%, do not provide the same level of efficacy, as they may evaporate too quickly and lack the required contact time to effectively eliminate pathogens. Higher concentrations, like 80%, may also be less effective for disinfection purposes because they can evaporate too rapidly, preventing sufficient contact time with surfaces or tools. Therefore, using 70% ethyl alcohol is the standard recommendation for proper disinfection in a cosmetology setting.