Which action is prohibited in a cosmetology establishment?

Using unlicensed equipment or tools is prohibited in a cosmetology establishment because it poses significant health and safety risks to clients and practitioners. Licensed equipment and tools are regulated to ensure they meet specific safety and hygiene standards, which are crucial in a field that interacts closely with the skin and other sensitive areas of the body. Utilizing unlicensed tools can lead to infections, allergic reactions, or ineffective treatments, undermining the professionalism and safety that industry standards are designed to uphold.

On the other hand, providing skin care treatments, offering hair color services, and performing manicures are all standard practices within a licensed cosmetology establishment, provided that they are conducted by licensed professionals using approved techniques and products. These services are essential components of cosmetology and are permissible as long as they comply with the established regulations and requirements.