Final answer:
A cosmetologist monitors the water temperature by keeping one finger under the nozzle to sense temperature changes, which ensures a comfortable and safe experience for the client.
Step-by-step explanation:
A cosmetologist continues to monitor the water temperature during rinsing by keeping one finger under the nozzle. This allows the cosmetologist to immediately sense any fluctuations in temperature and adjust the controls accordingly to ensure client comfort and safety. Similar to the everyday experience of checking the water temperature before a shower the cosmetologist uses their own sensation to regulate the water temperature for their client.
During procedures involving water, such as hand-washing or rinsing hair, it's crucial that the temperature is appropriate. For example when you wet your hands with warm water you expect a comfortable temperature that won't scald your skin. The cosmetologist's ongoing monitoring of temperature plays a similar role in providing a comfortable and safe experience for their client.