California Cosmetology Written ExamClient Consultation and AnalysisMedium
Before applying an aniline-derivative permanent hair color for the first time, how long must a predisposition (patch) test typically remain on the client's skin before checking for a reaction?
- A1 week
- BImmediately, no waiting time is needed
- C24 to 48 hours
- D5 minutes
Show answer & explanationAnswer & explanation
Correct answer: C. 24 to 48 hours
A predisposition patch test for aniline-derivative dyes must be applied to the skin (typically behind the ear or inner elbow) and left for 24 to 48 hours to check for allergic reaction before proceeding with the color service.
Why the other options are wrong
- A. A week is excessive and not the standard waiting period.
- B. Skipping the wait defeats the purpose of the patch test.
- D. Five minutes is far too short to detect a delayed allergic reaction.
Predisposition (Patch) Test
A test applying a small amount of aniline-derivative dye to skin, left for 24-48 hours, to check for allergic reaction before a permanent color service.
- Required before first-time use of aniline-derivative tints
- Applied behind ear or inner elbow
- Redness, itching, or swelling = positive/contraindicated
- Must be repeated for each new formula used
Memory trick: Patch test = wait two sunsets before coloring.