What is a common method to assess a client's hair condition before a treatment?

Conducting a strand test is a vital method to assess a client's hair condition before any treatment. This process involves taking a small section of the client's hair to analyze its response to a product or treatment in a controlled manner. By applying the treatment to the strand, a stylist can observe how the hair reacts in terms of texture, color, and health indicators. This allows the stylist to gauge the appropriate strength and type of treatment needed for the client’s specific hair type and condition, ensuring a tailored approach that minimizes the risk of damage.

Other methods, such as measuring scalp pH or listening to styling preferences, while important in their own right, do not provide direct insight into the hair's structural integrity and response to chemical treatments. Documenting hair length may be helpful for maintenance purposes or to track growth, but it does not indicate the health or condition of the hair. Therefore, the strand test stands out as the most reliable and informative method for assessing a client's hair condition prior to treatment.