What is necessary when using any manual or mechanical device?

When using any manual or mechanical device in a cosmetology setting, adhering to the manufacturer's intended use is vital. This principle is key in ensuring the safety and efficacy of the device, as it is designed for specific functions and must be operated in a way that aligns with those specifications. Using a device outside of its intended purpose can lead to ineffective results or, more seriously, potential harm to clients and practitioners alike. By following the manufacturer's guidelines, cosmetologists can protect themselves and ensure they are providing safe and effective services.

Considering other aspects such as training, client consultations, and maintenance, while important in their own right, they do not directly address the immediate requirement of using the device correctly according to the manufacturer's instructions. For example, training is crucial for understanding how to use the device, but it is ultimately the adherence to the intended use that governs how safely and effectively the device can be applied in practice.