Barber Practice State Board Practice Exam

Which concentration of isopropyl alcohol is effective for disinfecting shears or razors?

1. 70%

2. 80%

3. 90%

4. 99%

The correct answer is: 99%

The effectiveness of isopropyl alcohol as a disinfectant for tools like shears and razors hinges on its concentration. A 70% concentration of isopropyl alcohol is generally considered optimal for disinfection. This concentration allows for the alcohol to penetrate the cell walls of bacteria and viruses effectively, leading to cell lysis and death. Higher concentrations like 80%, 90%, or 99% may evaporate quickly and might not have sufficient time to effectively penetrate and disinfect surfaces. In particular, while 90% and 99% can kill pathogens, they tend to evaporate too rapidly to be as effective as 70% in practical applications because they do not have enough contact time with the organisms to ensure complete disinfection. Therefore, focusing on the 70% solution aligns with established disinfection guidelines.