The Chemistry of Hair Relaxing

FavoriteLoadingAdd to favorites
  • Lesson Identification and TEKS Addressed

    Cluster : Human Services

    Course : Cosmetology II

  • TEKS Student Expectations

    • (1) The student consolidates the employability characteristics of a successful worker in the workplace. The student is expected to:
      • (C) review the technical knowledge and skills required to be successful in careers in the personal care service area
      • (D) assess time-management principles and techniques to achieve objectives and efficiently serve clients
      • (E) create and maintain records, including electronic records, of client services using safeguarding procedures to store and retrieve personal care client information
    • (2) The student consolidates academic skills to satisfy the requirements of cosmetology. The student is expected to:
      • (A) apply and defend principles of biology, identifying living tissues, cells and organisms to provide and select safe and effective personal care products and services
      • (B) merge principles of chemistry, explaining the composition, structure and properties of substances and of chemical processes to provide a broad range of personal care services
    • (3)The student implements rules and regulations established by the Texas Department of Licensing and Regulation. The student is expected to:
      • (A) apply and defend emergency policies and procedures regarding health and safety
      • (B) evaluate risks, including potentially hazardous situations, to maintain a clean record of safety when providing personal care services
      • (C) perform and complete all practical requirements as required by the Texas Department of Licensing and Regulation or the governing body
    • (4) The student categorizes and judges both the function and application of the tools, equipment, technologies and materials used in cosmetology. The student is expected to:
      • (A) examine and rank vendor resources to provide maximum benefit for clients, service providers, businesses or organizations
      • (C) use technology resources to analyze data and information in order to make appropriate recommendations and conclusions for personal care services
      • (D) evaluate techniques, principles, tools and instruments used to develop efficient and safe delivery of client services to enhance client satisfaction
    • (5) The student merges the concepts and skills of cosmetology to simulated and actual work situations. The student is expected to:
      • (A) design personal care services for individuals by recognizing and making informed decisions according to client needs and concerns
      • (B) create an individualized plan that reflects client preferences, needs and interests in order to create a course of treatment or action
  • Basic Direct Teach Lesson

    Instructional Objectives

    Student will:

    • analyze the chemicals of hair
    • explain the impact of acids, alkalis and pH on the hair and scalp
    • analyze material safety data sheets for chemical information
    • determine the relevance of posity, density, texture and elasticity of the hair for chemical services
    • describe structural changes that take place in hair as a result of chemical relaxers
    • demonstrate safety and sanitation precautions related to chemical relaxers
  • Rationale


    Cosmetologists who are skilled in the art of chemical hair relaxing are in great demand today. Chemical hair relaxing is used for clients of many nationalities who have extra curly hair. In salons, curl permanents and hair relaxers are priced higher than many other salon services. Therefore, it is of great benefit to you as a cosmetology students to become proficient in all of these services.

  • Duration of Lesson

    Five 45 minute class periods

  • Word Wall

    Chemistry: The science that deals with the composition, structures and properties of matter and how matter changes under different conditions

    Disulfide bond: Strong chemical side bond that joins the sulfur atoms of two neighboring cysteine amino acids to create one cysteine, which joins together two polypeptide strands like rungs on a ladder

    Hydrogen bonds: Relatively weak phyiscal side bonds that are the results of an attraction between opposite electrical charges easily broken by water as in wet setting, or heat as in thermal styling and reformed as the hair dries or cords

    Hydroxide relaxers: Relaxers with a very high pH, sometimes over 13

    No base relaxers: Relaxers that do not require application of a protective base

    Normalizing solutions: Conditioners with an acidic pH that condition the hair and restore the hair’s natural pH prior to shampooing

    pH (potential hydrogen): Represents the quantity of hydrogen ions

    pH scale: A measure of the acidity and alkalinity of a substance

    Salt bonds: Relatively weak physical side that are the result of an attraction between opposite electrical charges are easily broken by changes in pH as in permanent waving and reform when the pH returns to normal

    Thio relaxers: Relaxers that usually have a pH above 10 and higher concentration of ammonium thioglycolate than is used in permanent waving

  • Materials/Specialized Equipment Needed


    • computer with Internet for slide presentation
    • computers with Internet access (be sure to follow school district guidelines)


    • cardstock


    • acid-balanced shampoo
    • bowl and applicator brush
    • conditioner
    • disposable gloves
    • hard rubber comb
    • hydroxide relaxer
    • hydoxide neutralizer
    • manikins
    • plastic clips
    • plastic rattail comb
    • pre-neutralizing conditioner
    • protective base cream
    • shampoo cape
    • spray bottle
    • stand
    • styling comb
    • thio neutralizer
    • timer
    • towels

    • copies of handouts (see All Lesson Attachments tab)

  • Anticipatory Set

    Before class begins:

    Print the Chemical Hair Relaxing Flashcards (see All Lesson Attachments tab) on cardstock and separate. Laminate the cards, if possible. Place the cards in a basket. Some will be printed red (answers) and some will be printed black (statements).

    Display as many of the supplies from the Materials and Specialized Equipment Needed section as you have available on a table in the front of the classroom.

    These supplies will serve as a basic guide to the process of using chemicals to permanently straighten the hair.

    As students enter the classroom, have each one select one red (answers) and one black (questions) card from the basket. Each student will have two cards.

    When the class is settled, begin by asking the following questions:

    • Do you wish you had straight hair?
    • Why would someone with curly hair want straight hair?
    • Do you like studying chemistry?
    • Why do we need to know chemistry to straighten hair?


    Allow each student to read the black card (question) as the other studens try to decide if they have the correct answer by reading the red card. Place the question and corresponding answer cards on the wall with tape so that students may review for the quiz.

  • Direct Instruction with Special Education Modifications/Accommodations

    Introduce lesson objectives, terms and definitions.

    Distribute graphic organizer The Chemistry of Hair Relaxing Notes (see All Lesson Attachments tab) so that students may take notes during slide presentation.

    Introduce PowerPoint™ The Chemistry of Hair Relaxing (see All Lesson Attachments tab) and discuss how important an understanding of chemistry is in straightening hair.

    View YouTube™ video:

    Individual Education Plan (IEP) for all special education students must be followed. Example of accommodations may include, but are not limited to:

    • checking for understanding
    • providing assistance with note-taking

  • Guided Practice with Special Education Modifications/Accommodations

    Distribute handout Chemical Relaxers Product Data (see All Lesson Attachments tab) and explain to students that similar products produce different results depending on the client’s hair.

    Assign students to locate material safety data sheets (MSDS) on the Internet for various products and complete the worksheet.

    Remind students of the following tips:

    • any relaxer can burn the scalp if used the wrong way
    • lye is found in hair relaxers allowing the product to work but can burn the skin
    • do not leave the relaxer on longer than the directions say you should
    • use a neutralizing shampoo to wash out the relaxer
    • use a conditioner after the hair relaxer
    • ask for help for another cosmetologist

    Review the Cosmetology Administrative Rules (see All Lesson Attachments tab) for the general requirements of the Health and Safety Standards.

    These standards include:

    • clean and disinfect equipment, tools, implements and supplies before use on each client
    • use clean towels for each client
    • use clean cutting and shampoo capes for each client
    • use a sanitary neck strip or towel
    • employ good personl hygiene habits while providing cosmetology service

    Distribute the Client Consultation Card (see All Lesson Attachments tab) from the Client Consultation lesson and review the Hair and Scalp Analysis section.

    Explain the procedure for chemical hair relaxing:

    • determine the impact of the acids, alkalis and pH on the hair scalp
    • explain the relevance of porosity, density, texture, elasticity and disorders of the hair for chemical services
    • differentiate between a soft curl and a chemical relaxer
    • identify factors critical to hair and scalp analysis
    • compare chemical texture services and structure changes that occur in the hair

    Demonstrate how to apply the chemical relaxer on a volunteer or a manikin.

    Students will work independently practicing safety and sanitation techniques.

    Re-teach as needed.

    Individual Education Plan (IEP) for all special education students must be followed. Example of accommodations may include, but are not limited to:

    • peer tutor
    • shortened assignment

  • Independent Practice/Laboratory Experience with Special Education Modifications/Accommodations

    Students will:

    • work independently practicing applying a chemical relaxer
    • work independently and perform strand tests following manufacturer’s processsing directions
    • rinse and shampoo thoroughly with warm water to remove traces of relaxer

    Important: Students should follow the manufacturer’s processing directions in order to achieve the desired affect.

    Distribute Rubric for Chemical Hair Relaxing (see All Lesson Attachments tab) so that students may know what is expected.

    Individual Education Plan (IEP) for all special education students must be followed. Example of accommodations may include, but are not limited to:

    • provide more time for practice
    • frequent feedback

  • Lesson Closure

    Review lesson objectives, terms and definitions.


    Review the flashcards from the Anticipatory Set and allow students to match the answers with the correct statements.

    Remind them to study for quiz.

  • Summative/End of Lesson Assessment with Special Education Modifications/Accommodations

    Students will present finished manikin or client with straight hair.

    Students will be assessed with appropriate rubric.

    Distribute Chemical Hair Relaxing Quiz (see All Lesson Attachments tab) to assess students’ knowledge.

    Individual Education Plan (IEP) for all special education students must be followed. Example of accommodations may include, but are not limited to:

    • oral quiz if needed
    • use notes for quiz
    • reduce number of quiz statements

  • References/Resources


    • Halal, J. (2009). Hair structure and chemistry simplified: Exam review/John Halal. Clifton Park, NY: Milady/Cengage Learning.
    • Milady standard cosmetology: Situational problems. (2012). Clifton Park, NY: Cengage Learning.



  • Additional Required Components

    English Language Proficiency Standards (ELPS) Strategies

  • College and Career Readiness Connection

    AchieveTexas Career Cluster Crosswalks

    The Career Cluster Crosswalks housed on the AchieveTexas website provide Texas teachers with a direct connection between their CTE course TEKS and the College and Career Readiness Standards (CCRS). Language Arts, Mathematics, Science, Social Studies, and Cross-Disciplinary integration are the focus of the CCRS. These college and career readiness standards are essential in the planning and delivery of CTE lessons. The extent to which the integration occurs is determined by the methods and strategies utilized by each teacher.

    Career Cluster Crosswalks for Education and Training, Hospitality and Tourism, and Human Services Career Clusters can be found at:

  • Recommended Strategies

    Reading Strategies

    Other articles pertaining to this lesson that students may read include:

    Reading Strategy:

    • Ask and Answer Questions
      Having students form their own questions helps them recognize confusion and encourages active learning. Instruct students:
      • Before reading, think about the subject based on the title, chapter heads, and visual information. Make note of anything you are curious about.
      • While reading, pause and write down any questions. Be sure to ask questions if there is confusion.
      • Look for the answers while reading. Pause and write down the answers.
      • Were all the questions answered? Could the answers come from other sources?

  • Quotes

    Forget not that the earth delights to feel your bare feet and the winds long to play with your hair.
    -Khalil Gibran

    I used to be very insecure about my curly hair, because I lived in a country where everybody had blonde straight hair.
    -Diane von Furstenberg

    I have very curly hair and I straighten it every day – it takes maybe two minutes. I can’t imagine anyone having a bigger challenge than I do in the kinkiness that is my crazy ‘fro.’
    -Ginnifer Goodwin

    I love wearing my hair curly, but turning the curling iron all the way up creates curls that look really made up and artificial.
    -Camila Alves

    I was 23, and that was my first professional job. Anybody who has curly hair knows you don’t want it to be brushed out because it becomes a never-ending tangle.
    -Judy Davis

  • Multimedia/Visual Strategies


    • The Chemistry of Hair Relaxing
    • Presentation Notes – The Chemistry of Hair Relaxing


    Files for downloading:

  • Graphic Organizers/Handout

    Graphic Organizers:

    • The Chemistry in Hair Relaxing Notes
    • The Chemistry in Hair Relaxing Notes (Key)
    • Client Consultation Card


    • Chemical Hair Relaxing Flashcards
    • Chemical Hair Relaxing Quiz
    • Chemical Hair Relaxing Quiz (Key)
    • Chemical Relaxers Product Data
    • Cosmetologists Administrative Rules
    • Rubric for Chemical Hair Relaxing

    Files for downloading:

  • Writing Strategies

    Journal Entries:

    • People want to have straight hair because ….
    • Curly hair is difficult to keep neat because …
    • Long, straight hair is …..
    • Long, curly hair is ….
    • My preferance in chemical relaxers is ….

    Writing Strategy:

    • RAFT
      • Role – cosmetologist
      • Audience – chemical relaxer manufacturer
      • Format – business letter
      • Topic – requesting directions on product be written more clearly

    Flash Cards
    Cosmetologists must memorize terminology associated with their specialty field. Like most other industries, cosmetologists should be well-versed in industry terminology to provide the best type of care for their clients. To engage students in this activity, make a list of terms and their definitions. Write the definitions on one side of a flash card and on the other write the term. Make sure the backside of the card cannot be seen during the activity. To help students learn the names of supplies and tools used during their work, take pictures of the items and glue the pictures onto a flash card with the answer written on the back of the card.

  • Communication 90 Second Speech Topics

    • Name three products that are used in hair relaxers
    • The purpose of the neutralizer in chemical relaxing treatments is ….
    • The common ingredients in the Thio relaxer and permanent waving solution are ….
  • Other Essential Lesson Components

    Enrichment activity

    Skill Activity
    Cosmetologists are responsible for ensuring makeup application, hairstyles or nails are exactly what the client desires.

    A fun activity to sharpen the beauty skills of a cosmetologist, is to write several different styles onto an index card and allow students to choose a card.

    With a manikin, have the cosmetologist create the look stated on the index card.


    • 1950s pinup
    • prom night
    • southern belle
    • Gothic Lolita

    Make sure to only place styles on the index cards the student have recently studied so the student is able to put theoretical study into practical use.

    To make the activity more interesting, give the students a time limit and allow the other students to critique their work.

  • Family/Community Connection

    The fix-it activity can be a fun way to end a hard week in school.

    Ask for a few volunteers from the class to be made-under. Take these students into another room and mess up their makeup, hair or nails.

    Pair up the fix-it student with a peer who is responsible for correcting the mistakes on the student’s face, hair or nails.

    Allow the students only 30 minutes to work. Encourage using techniques and skills learned during class to fix the mistakes on the other student.

    Have students interview a professional operator/shop owner in the community.

  • CTSO connection


    • Cosmetology
      Students will demonstrate their skills in haircutting, hair styling and long hair design in four separate tests. All work is performed on manikins so everyone begins with the same model and the same type of hair. Contestants will create one 90 degree women’s haircut, one woman’s and one man’s cut from a finished photo. A display of creativity is seen in the long hair segment of the competition where these future salon professionals demonstrate their own design skills. A parade finale closes the contest with each contestant walking down the stage with their completed manikins to present to the audience.
  • Service Learning Projects

    Successful service learning project ideas originate from student concerns and needs. Allow students to brainstorm about service projects pertaining to lesson. For ideas, visit:

    Possible idea:
    Provide services to residents in a local nursing home and for the special populations at your high school to practice the techniques learned.

  • All Attachments