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.

Questions and answers, explained

All 7 questions above, with the correct answer and why it is correct. Everything here is on patch tests and strand tests.

1. How far in advance of an aniline derivative tint must a predisposition test be performed?

   • A24 to 48 hoursCorrect
   • BImmediately before the service
   • CSeven days
   • DTwo hours

   Why: The predisposition or patch test is applied 24 to 48 hours ahead so a delayed hypersensitivity reaction has time to appear. A test read immediately or after two hours would miss exactly the reaction it exists to catch. Seven days is longer than any manufacturer requires and would not reflect current sensitivity.

   Reference Clinical domain: hair coloring and lightening; predisposition test

2. Which hair removal product requires a patch test before first use?

   • AA chemical depilatory creamCorrect
   • BA pair of stainless steel tweezers
   • CCotton thread used for threading
   • DA disposable razor used for shaving

   Why: A depilatory is a strong chemical applied to skin and can provoke a reaction, so a small test area is checked before general use. Tweezing, threading and shaving are mechanical rather than chemical methods, and there is no formulation to react to — the risks there are irritation and technique, not allergy.

   Reference Theory domain: facials, makeup and hair removal; patch testing

3. What does a test curl during processing tell the cosmetologist?

   • AWhether the client is allergic to the waving lotion
   • BHow many strands of hair occupy each square inch
   • CWhether the wave has processed enoughCorrect
   • DWhich developer volume the neutralizer will require

   Why: Unwinding a rod partway and checking whether a firm S-shape has formed is the only reliable way to judge processing, because timing charts cannot account for an individual head's porosity. Allergy is checked before the service, density is measured during analysis, and a neutralizer does not use developer volumes at all.

   Reference Clinical domain: permanent waving and chemical relaxing; test curls

4. Where is a predisposition test applied?

   • AOn a strand of hair taken from the nape
   • BOn the palm of the hand
   • CBehind the ear or on the inner elbowCorrect
   • DAlong the front hairline

   Why: The test goes on thin, sensitive skin behind the ear or in the bend of the elbow, where a reaction is visible and away from the face. A strand of hair tests color result, not allergy — that is a strand test and answers a different question. The palm's thick skin and the hairline's visible position both make them wrong choices.

   Reference Clinical domain: hair coloring and lightening; predisposition test

5. How is a relaxer's progress checked during processing?

   • ABy timing strictly to the chart on the container and never checking
   • BBy asking the client whether her scalp has started to tingle
   • CBy rinsing a section and examining it under the dryer
   • DBy periodic strand tests, pressing the hair smooth and releasing itCorrect

   Why: Periodic strand testing — smoothing a small section and watching whether it stays straight or beats back to curl — is the only way to judge an individual head, because porosity and texture vary far more than a timing chart can allow for. Relying on the clock alone risks over-processing, scalp sensation is a warning sign rather than a measure of progress, and rinsing ends the service.

   Reference Clinical domain: permanent waving and chemical relaxing; strand testing

6. A patch test site shows redness, swelling and itching after 24 hours. What is the correct action?

   • ADo not perform the service; refer her to a physicianCorrect
   • BProceed using half the normal developer strength
   • CProceed but shorten the processing time
   • DRepeat the test on the other side of the neck to confirm

   Why: A positive patch test is an absolute contraindication. The service is not performed at any strength or duration, because the reaction is to the aniline derivative itself and not to the amount of it. Repeating the test on the opposite side exposes the client to the same allergen a second time for no useful information.

   Reference Clinical domain: hair coloring and lightening; contraindications

7. What does a strand test determine?

   • AWhether the client is allergic to the product
   • BHow much the hair can stretch before breaking
   • CThe number of strands per square inch
   • DThe processing time and the result the formula will giveCorrect

   Why: A strand test applies the actual formula to a small section to preview the color result and establish timing. Allergy is checked by the predisposition test, stretching is the elasticity test, and strands per square inch is density. The four tests answer four different questions and the exam relies on candidates confusing them.

   Reference Clinical domain: hair coloring and lightening; strand test

Drill the whole domain

• Hair Coloring and Lightening (19.5%)
• Permanent Waving and Chemical Relaxing (17%)
• Facials, Makeup and Hair Removal (8%)

Other topics

• Florida cosmetology license requirements
• Florida salon licenses and inspections
• What a Florida cosmetology license covers
• Salon disinfection rules, step by step
• Corrective color and the law of color
• Developer volumes and how much they lift
• Perm rods, wrapping and processing
• Hydroxide relaxers versus thio relaxers
• Nail disorders: when to refuse the service
• Gray coverage and resistant hair
• Waxing contraindications and safety
• Elevation and guidelines in haircutting
• Blood exposure in the salon
• Hair and scalp analysis before a service
• Thermal styling and heat safety

See all topics · Study Guides · Full practice exam