What should be done before applying any chemical product to the hair?

Before applying any chemical product to the hair, it is essential to perform a strand test. This practice helps to determine how the hair will react to the chemical treatment and is critical for assessing the hair's condition and porosity.

Conducting a strand test allows the stylist to evaluate the processing time required for the desired outcome, ensuring they do not over-process the hair and potentially cause damage. It offers insight into how the hair's texture may change with the chemical and helps to predict the final color or texture result. This precautionary step is vital for safeguarding the integrity of the hair and achieving the best results.

The other options, while they may have their own benefits in certain contexts, do not serve the same fundamental purpose as a strand test. A scalp massage could improve relaxation but does not assess the hair's reaction to chemicals. Washing the hair with shampoo may be necessary for cleanliness, but simply cleansing does not provide information on how the hair will chemically respond. Lastly, applying a heat protector is useful when using heat styling tools, but it does not replace the need for understanding how each chemical will affect the hair.