What should be done before applying any chemical treatment to hair?

Performing a strand test before applying any chemical treatment to hair is essential because it helps determine how the hair will react to the chemicals. This test involves applying the chemical treatment to a small, discreet section of hair to assess the hair's strength, elasticity, and overall condition. By doing so, a stylist can gauge the appropriate processing time and potential outcomes, thereby minimizing the risk of damage or unwanted results.

In contrast, washing with shampoo, applying conditioner, or using heat styling tools may alter the hair's condition but do not provide critical information regarding how the hair will specifically respond to the chemical treatment being applied. Each of those steps may be part of a broader hair care routine but is not specifically designed to evaluate the safety and efficacy of the chemical application. Therefore, conducting a strand test is the most responsible and informed approach to ensure the best results with minimal damage.