Patch tests and strand tests

Candidates mix these two up constantly, and the exam knows it. They answer different questions: one asks whether the service may happen at all, the other asks what it will look like. Neither substitutes for the other.

Predisposition (patch) test	24 to 48 hours before an aniline derivative tint
Where it goes	Behind the ear or on the inner elbow
A positive site	Redness, swelling, itching — do not perform the service; refer to a physician
Strand test	Predicts the processing time and the result the formula will give
Test curl	Tells you whether a perm has processed enough
Checking a relaxer	Periodic strand tests — press the hair smooth and release it
Chemical depilatory cream	Patch test before first use
Unknown chemical history	Test on a cut strand before any service at all

Where the point is lost: The cut-strand test is the one worth remembering for the scenario items. A client who cannot recall whether her last service was a thio perm or a hydroxide relaxer has handed you a question with breakage as the penalty for guessing — and a strand cut from her head answers it today, for free. Choosing the more common service, or choosing a milder product, are both guesses wearing different clothes.