Hydroxide relaxers versus thio relaxers

One distinction generates more exam items than any other in this domain, and it also generates the most real-world breakage: the two relaxer chemistries are incompatible, in both directions, permanently.

Questions and answers, explained

All 12 questions above, with the correct answer and why it is correct. Everything here is on hydroxide relaxers versus thio relaxers.

1. A client's hair was relaxed with a sodium hydroxide product eight months ago. She now wants a permanent wave. What is the correct response?

   • AProceed, because eight months is long enough for recovery
   • BProceed using an acid-balanced wave, which is gentler
   • CDecline to perm the relaxed hairCorrect
   • DApply a protein filler first, then wave normally

   Why: Hydroxide relaxing converts disulfide bonds into lanthionine bonds permanently, and those bonds cannot be broken and reformed by a thio wave. Waving that hair causes severe breakage. Time does not reverse lanthionization, a gentler acid wave still relies on the same chemistry, and no filler restores the missing bonds. Only new growth could ever be permed.

   Reference Clinical domain: permanent waving and chemical relaxing; incompatible chemistry

2. A client cannot recall whether her previous texture service was a thio perm or a hydroxide relaxer. What should be done?

   • AAssume it was a thio perm, which is the more common service
   • BProceed with the mildest product available on the whole head
   • CPerform a test on a cut strand before any serviceCorrect
   • DAsk her to return once she has contacted her previous salon

   Why: A test on a cut strand shows how the hair actually behaves and costs nothing but time, which is exactly what the missing history would have told you. Assuming the more common service is a guess with breakage as the penalty. A mild product on incompatible chemistry still breaks hair, and sending the client away discards the diagnostic that settles it today.

   Reference Clinical domain: permanent waving and chemical relaxing; unknown history

3. What permanent chemical change does a hydroxide relaxer make to the hair?

   • AIt oxidizes the disulfide bonds so they can be reformed later
   • BIt converts disulfide bonds into lanthionine bondsCorrect
   • CIt dissolves the cuticle and exposes the cortex
   • DIt breaks hydrogen bonds that reform when the hair dries

   Why: Hydroxide removes a sulfur atom from a disulfide bond and converts it into a single lanthionine bond, a process called lanthionization. It cannot be reversed, which is why the hair can never take a thio wave afterwards. Oxidation is what a perm neutralizer does, hydrogen bonds govern only temporary sets, and the cuticle is not dissolved.

   Reference Clinical domain: permanent waving and chemical relaxing; lanthionization

4. Which of these is a hydroxide relaxer commonly described as a lye relaxer?

   • AAmmonium thioglycolate, the same active used in cold waving
   • BHydrogen peroxide at 20 volume
   • CSodium hydroxideCorrect
   • DGlyceryl monothioglycolate

   Why: Sodium hydroxide is the lye relaxer; potassium, lithium and guanidine hydroxide are the no-lye alternatives. Ammonium thioglycolate and glyceryl monothioglycolate are thio compounds used in permanent waving and in thio relaxers, which work by an entirely different mechanism. Peroxide is an oxidizer and straightens nothing.

   Reference Clinical domain: permanent waving and chemical relaxing; relaxer types

5. A guanidine hydroxide relaxer is mixed on site from which two components?

   • AA calcium hydroxide cream and a guanidine carbonate activatorCorrect
   • BA sodium hydroxide base and a hydrogen peroxide developer
   • CA thio cream and an alkaline neutralizing shampoo
   • DA protein filler and an ammonium thioglycolate lotion

   Why: A guanidine relaxer is supplied as a calcium hydroxide cream and a guanidine carbonate activator, mixed immediately before use. It is marketed as gentler on the scalp but is still a hydroxide relaxer and still causes lanthionization. Peroxide, thio compounds and fillers all belong to entirely different services.

   Reference Clinical domain: permanent waving and chemical relaxing; no-lye relaxers

6. What does the neutralizing shampoo used after a hydroxide relaxer actually do?

   • AIt rebuilds the disulfide bonds that the relaxer broke apart
   • BIt re-curls any hair that was over-straightened during the service
   • CIt restores the hair to its normal acidic pHCorrect
   • DIt seals the lanthionine bonds so they cannot revert

   Why: The neutralizing shampoo is acid-balanced and its job is to stop the relaxer's action and bring the pH back down. It rebuilds nothing — lanthionization is irreversible, so there is no bond to restore and none that could revert. It also cannot restore curl that has been chemically removed.

   Reference Clinical domain: permanent waving and chemical relaxing; neutralizing shampoo

7. What is the purpose of applying a protective base cream before a base relaxer?

   • ATo shield the scalp and hairline from the relaxerCorrect
   • BTo slow the chemical action so the relaxer processes evenly
   • CTo add moisture to the hair before the chemical is applied
   • DTo help the relaxer adhere to the most resistant sections

   Why: Base cream is an oil-based barrier applied to the scalp, hairline and ears so a strongly alkaline product cannot reach skin. It is not meant to touch the hair itself, so it neither moisturizes nor helps the product adhere, and it does not alter the speed of the chemical reaction on the strand.

   Reference Clinical domain: permanent waving and chemical relaxing; base creams

8. What distinguishes a no-base relaxer from a base relaxer?

   • AA no-base relaxer is safe to apply directly onto broken skin
   • BA no-base relaxer contains its own protective ingredientCorrect
   • CA no-base relaxer needs no neutralizing shampoo afterwards
   • DA no-base relaxer works without changing the hair's bonds

   Why: A no-base relaxer has the protective agent built into the formula, so a separate base cream is not applied over the whole scalp — though the hairline and ears are usually still protected. It is still a caustic chemical, still requires neutralizing, and still changes the bonds. Nothing makes any relaxer safe on broken skin.

   Reference Clinical domain: permanent waving and chemical relaxing; base and no-base

9. On a virgin relaxer application, where is the product applied first?

   • AAt the scalp, since new growth is the most resistant area
   • BOn the ends, working upward toward the scalp last
   • CA short distance away from the scalpCorrect
   • DEverywhere at once so all sections process together

   Why: Application begins roughly a quarter to half an inch off the scalp and the scalp area is done last, because body heat makes that zone process fastest. Starting at the scalp over-processes the new growth and risks a chemical burn. Beginning at the ends leaves the mid-shaft untreated, and applying everywhere at once removes all control over timing.

   Reference Clinical domain: permanent waving and chemical relaxing; virgin relaxer application

10. A client had a thio relaxer six months ago and now asks for a sodium hydroxide relaxer. What is correct?

    • AProceed, because both products are relaxers and work the same way
    • BProceed after applying a protein filler to the previously relaxed hair
    • CDo not apply hydroxide over thio-relaxed hairCorrect
    • DProceed if a strand test shows no immediate breakage

    Why: Thio and hydroxide are incompatible chemistries and must never be layered in either direction; the combination causes severe breakage. Only new growth could be treated, and switching systems mid-head is not a judgment call. No filler bridges the incompatibility, and a strand test that survives the first minutes does not predict what happens over the full processing time.

    Reference Clinical domain: permanent waving and chemical relaxing; incompatible chemistry

11. Relaxer strengths are labeled mild, regular and super. What determines the choice?

    • AThe hair's texture, porosity and how resistant it isCorrect
    • BHow straight the client would like the finished result to be
    • CThe length of the hair from the scalp to the ends
    • DHow long it has been since the client's last relaxer service

    Why: Strength is matched to the hair itself: coarse, resistant hair takes super, medium hair takes regular, and fine, porous or previously damaged hair takes mild. Choosing a stronger product because the client wants a straighter result is how hair is destroyed — degree of straightening is controlled by processing and smoothing, not by escalating strength. Length and interval affect timing rather than product selection.

    Reference Clinical domain: permanent waving and chemical relaxing; relaxer strength

12. A client's hair was lightened two levels last week. She now wants a hydroxide relaxer. What is correct?

    • ADecline the relaxer on lightened hairCorrect
    • BProceed with a mild-strength relaxer and a shorter processing time
    • CProceed after a deep conditioning treatment the same day
    • DProceed only if the client signs a release form accepting the risk

    Why: Lightening has already broken disulfide bonds and raised porosity, and a hydroxide relaxer on that hair commonly results in breakage. Reducing strength or timing does not change the underlying weakness, a conditioning treatment coats but does not rebuild, and a release form documents consent without making an unsafe service safe.

    Reference Clinical domain: permanent waving and chemical relaxing; lightened hair

Drill the whole domain

• Permanent Waving and Chemical Relaxing (17%)

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