What is the purpose of a strand test and a patch test before a chemical service?

• A. Patch test screens for allergies; strand test predicts lift, tone, and processing time on the client's hair
• B. Patch test measures porosity; strand test checks scalp sensitivity
• C. Strand test checks color saturation; patch test calibrates developer
• D. Patch test determines final shade; strand test times processing

Answer: (C)

This is about safety and planning the service. A patch test checks for allergic reactions to the hair color ingredients, which helps protect you from potential skin irritation or a reaction before any chemical product is applied to the scalp. The strand test uses a small section of hair to preview what will happen during the service: how much the hair will lift, what the resulting tone will look like, and roughly how long the processing will take. This combination lets the stylist tailor timing and shade expectations for the client’s hair.

So the best choice reflects that the patch test screens for allergies and the strand test predicts lift, tone, and processing time on the client’s hair. Other options mix up what these tests assess—for example, porosity, scalp sensitivity, developer calibration, or final shade determination—none of which capture the primary purposes of patch and strand testing.