History of Relaxers and How Relaxers Work - Curly Chic

History of Relaxers and How Relaxers Work

History of relaxers

Back in 1998 Dr. Ali Syed helped write a paper regarding content on the history of relaxers and how relaxers work.  I decided to post his writings for those who are interested in learning more about his writings on the relaxer system. Also, how relaxers effects the chemistry, porosity, swelling, loss of elasticity, the cuticles of African or textured hair and its damaging effects. In this paper, African or textured hair is referred to as excessively curly. This is the primary reason why we all should embrace my natural hair texture. Furthermore, with the right products and proper technique textured hair is easy to manage.

I am reposting this article in which I previously  posted on my blog in 2011.

Literature by Ali N. Syed, Hasan Ayoub and Anna Kuhajda

In literature, innovation is defined as the initiation or adoption of new products, processes or ideas by organizations. Such innovations have taken place in the care of excessively curly hair. These developments did not catch the attention of the masses in the US because a relatively small segment of the population possesses curly hair. On a worldwide scale, however, the number becomes larger when we include individuals from Africa, the Caribbean, South America, the Middle East, Asia and North America, According to some estimates, this segment with excessively curly hair has grown to equal a $1.5 billion (US) industry.

The History

Before discussing the history of the curly hair-care industry, it is necessary to understand the nature of excessively curly hair. Compared to straight hair, excessively curly hair is like a twisted ribbon in terms of its physical configuration. It is difficult to comb both in its wet and dry states, is hard to style and is highly unmanageable. More fragile than straight hair, excessively curly hair breaks more readily upon stretching, excessive combing and brushing. Thus, excessively curly hair requires special handling and specially formulated products that are different from Caucasian hair-care formulas.

Madame C.J. Walker

In the early 1900s, Sarah Breedlove, later known as Madame C.J. Walker, an African American domestic worker, invented a pomade of various oils. It revolutionized the hair-styling practices of African-American women by making excessively curly hair softer, shinier and somewhat easier to comb. The pomade, however, did not straighten hair, therefore, African~American women could not achieve styles like those worn by Caucasian women. To address this need, Madame Walker invented a straightening comb in 1905 that, when heated on a stove and used in conjunction with her pomade, made hair shiny, silky and temporarily straight. This method was first known as the Walker method, and later as “hair pressing.”

Next 40 Plus Years

For the next 40-plus years, the problems of extremely curly hair were not fully addressed by any of the existing hair-care businesses because of a technology void. In the ’50s, however, George E. Johnson founded Johnson Products Company. By 1965, the company introduced an innovative permanent hair straightener for African-American consumers that eliminated the need for temporary hair straightening by the Walker method.

Similarly, Childrey & Doty introduced a hair-relaxer cream in 1962 for Summit Labs. The relative advantages of this innovation over the Walker method were many, and the adoption of permanent hair straightening advanced rapidly. The innovation of chemical hair straightening had social ramifications, too: for the first time African-American women could wear styles that were predominant in North American culture.

Relaxer System – The 70’s

Competitive forces began to address the weaknesses of this first-generation relaxer cream in the early ’70s. This relaxer tended to overprocess and diminish the strength of hair, irritate the scalp and be difficult to rinse. It also had a short shelf life because of the separation of oil and water phases present in the relaxer cream. Upon separation of the cream, the active ingredient (sodium hydroxide, a lye), being soluble in water, transferred to the water phase, thereby resulting in inconsistent straightening of the hair.

Revlon seized the opportunity to introduce a cream called a “texturizing relaxer.” It was more stable to heat and cold temperatures and provided more scalp comfort by being less irritating. The Revlon relaxer straightened hair slightly less than the Johnson Products relaxer but was still acceptable to hairstylists and consumers. It managed to create a sizable market share and segmented the market into two: the Johnson Products relaxer was preferred by hairstylists who wanted much straighter hair and Revlon’s cream was preferred by hairstylists who wanted a texturized or less straight, look. In the mid ’70s, Revlon also introduced a conditioning/detangling shampoo which imparted tremendous ease of combing, thereby reducing combing force significantly.

By 1978. the competition cost Johnson Products Company a significant loss of market share. Johnson fought back by introducing its own version of the texturizing relaxer cream. In 1980, the company introduced a relaxer cream that incorporated a conditioning, and softening quaternary ammonium polymer. This  innovation allowed easier combing and delivered conditioning benefits while simultaneously relaxing the hair. Although radical in this latest benefit the cream suffered an inherent disadvantage: it created even more scalp discomfort than the first generation of relaxers. This defect hindered the success or the new relaxer.

Relaxer System – Beyond

While most of the attention was being given to sodium hydroxide-based cream relaxers, Carson Products Company introduced a new patented two-component cream relaxer in 1978 which was formulated with the active ingredient guanidine hydroxide, produced by mixing a cream containing calcium hydroxide with a liquid activator containing guanidine carbonate. This innovation was significantly less irritating to the scalp compared to other relaxers and was marketed as a no-lye relaxer. Although it provided perceivably more scalp comfort, the Carson innovation did not meet market standards in terms of case of combing and conditioning.

In 1982, Johnson Products Company licensed the no-lye relaxer technology from Carson and combined it with their own quaternary ammonium polymer conditioning technology. This combination of Carson and Johnson technologies produced a significantly better conditioning cream relaxer (two-component) with maximum scalp comfort, ease of wet and dry combing and the creation of a silky-soft hair texture.

In 1984, Soft Sheen Products, a newcomer to hair relaxing, introduced a “texturizing” relaxer cream. This new product came with an after-relaxer (pre-neutralizing) conditioner which softened and conditioned hair to the same degree as Johnson’s creme relaxer while limiting the scalp discomfort associated with Johnson’s relaxer with sodium hydroxide. Although this approach represented an advancement over Johnson’s relaxer, the conditioning and softening properties of the new Soft Sheen product were open for improvement.

In 1985, Avlon Industries Inc. introduced a relaxer system based upon scalp type. For a normal scalp, its creme relaxer contained sodium hydroxide as an active ingredient. For the sensitive scalp, the company introduced a creme relaxer (two-component) containing guanidine as an active ingredient. Both relaxers had a pre-relaxer conditioner with quaternary ammonium polymers, a relaxer which straightens hair, a reconstructing conditioning agent and an acidic agent with conditioning polymers. The relaxer system provides maximum conditioning before, during and after relaxing.

Over the years, Avlon received feedback about its relaxer system from hairstylists. They said their clients’ hair was thinning and drying out after using the no-lye relaxers during a three to four year period. Avlon researchers discovered that hair fibers act as a permeable membrane whereby liquids could flow into the inside of hair, swelling it to it certain degree. This swelling created pressure inside the hair, known as “osmotic pressure.” They also found that guanidine hydroxide swelled the hair slightly more than sodium hydroxide, consequently creating a higher osmotic pressure inside the hair shaft.

In 1995, Avlon found a new conditioning polymer that not only made hair comb easily and feel soft, but also increased its elasticity and tensile strength. Ultimately, this relaxer system, compared to other relaxers. left more elasticity and tensile strength in the hair and minimized swelling. Thus, this innovation produced stronger hair with respect to stretchability and cuticle erosion.

The Chemistry

As noted above. there has been a significant degree of achievements in the area of hair straightening. Therefore, it is appropriate at this point to discuss the chemistry of straightening hair.

Hair fibers are made up of keratin. a water-insoluble protein which is comprised of polypeptide chains arranged parallel and bonded together by three types of cross linkages; cystine (or disulfide) bonds, hydrogen bonds, and salt linkages. A simplified schematic of keratin is shown in Figure 1.

Modern hair relaxers contain alkali metal hydroxides and guanidine as active straightening agents. When hair is treated or exposed to these relaxers for 15 to 20 min, primarily one third of the cystine bonds are transformed to lanthionine bonds, along with minor hydrolysis of peptide bonds, although the reaction mechanism is not fully understood. So far, one possible mechanism has been present by Tolgyesi and Fang in Figure 2.

The treatment of hair fibers with relaxer creams for a duration of 15 to 20 min leaves hair fibers considerably damaged, dry and rough in tactile feel. The damaging effects of relaxers are discussed below.

Damaging Effects

Most relaxer creams are comprised of active ingredients like sodium hydroxide, potassium hydroxide, lithium hydroxide or guanidine (two-component system). During the process of relaxing, one-third of the cystine bonds are modified permanently to lanthionine bonds, which decrease the elasticity and tensile strength along with cuticular damage done to the surface of the hair.

The stress-strain curves show the degree of loss of elasticity and tensile strength in Figure 3 due to the treatment of relaxer creams.

The damaging effects of hair relaxer creams are not limited to a significant loss in elasticity and tensile strength; they include other damages such as osmotic swelling. During this relaxing process, hair undergoes swelling by 50% or more and, upon rinsing with water, abruptly swells another 20 to 30% within the first 15 to 20 sec. Generally, this swelling is out of control. The hair ruptures and develops cracks both longitudinally and radially as shown in the electron micrograph in Figure 4. Over a period of time, these cracks are further prone to insult by the bristles of the styling brush or teeth of the styling comb.

The removal of cuticles is not only seen by SEM micrographs but can also be quantified by using a modified technique of Sandhu et aI, where loss of cuticles is measured as hydrolyzed protein via the Lowry Spectrophotometric Assay. Other damaging effects of relaxing creams are an increase in hair porosity, a decrease in the moisture content of hair and a rough, tactile feel of hair after the relaxing process.

The elimination or alleviation of all the various damaging effects have been the objective of this study. The following techniques are employed to reduce these damaging effects.

Loss of elasticity/tensile strength:

Here, a relaxer formula containing cationic polyamines of high molecular weight (600,000 to 1,000,000) was compared to a control formula without the cationic polyamines. The formulas are shown in Table 1.

Twelve-inch long hair fibers of similar diameter (71-80 microns) were obtained from DeMeo Brothers, New York. These dark brown Caucasian fibers were cleansed with a 10% solution of sodhum lauryl sulfate, rinsed thoroughly for 30 min and allowed to dry overnight. Each fiber was then cut in half and crimped into 30mm sections using a crimp press.

The hair section closest to the root was designated as the control,and the section downstream was used for the experimental relaxer. The tensile strength of the treated fibers with control relaxer (without cationic polyamine) was determined under wet conditions using a tensile tester.

The strength was determined by the amount of work required to extend the fihers to 20% of their original length at a rate of 10 mm/min. The experimental group was treated with relaxer containing cationic polyamine. The tensile strength of these fibers was determined in exactly the same manner as in the control group. The data for both groups of fibers is shown in Tables 2a and 2b.

These results indicate that the experimental group treated with relaxer containing polyamine exhibits a lower loss of tensile strength (M = – 0.528, SD = 0.085) as compared to the control group (M = -0.6:35, SD = 0.094). This difference is significant at t(40) = -3.903, P < 0.000, two-tailed.


The swelling studies were done using a laser micrometer that measures the major and minor axis of the fiber simultaneously. Again, Caucasian hair from DeMeo Brothers was used because of its relative uniformity compared to excessively curly hair, which tends to be highly irregular in its diameter as shown in previous studies by Syed et al. In this study, Caucasian hair with a diameter range of 71-80 microns was selected and equilibriated at 65% relative humidity at 21 °C for 24 hr. These fibers were then immersed in relaxer for 18 min. After 18 min, excess relaxer was gently removed, and the diameter measured again. The diameter measurements were continued through the rinsing phase. Figure 5 shows a graph comparing hair fiber swelling in hair relaxer without any de-swelling ingredients vs. hair relaxer containing de-swelling ingredients, These de-swelling ingredients are starch hydrolysates, sugars, sorbitol, glycerin and other salts.

Hair fibers treated with the control relaxer without any deswelling ingredients exhibited a swelling of 45.2% at 18 min in relaxer and peaked at 80.8% when rinsed with water. Hair fibers using cream relaxer with starch hydrolysates swelled to 19.8 % before rinsing and 38.5% upon rinsing.

Therefore, hair fibers treated with relaxer containing starch hydrolysates and other de-swelling ingredients exhibited significantly less swelling compared to relaxer without de-swelling ingredients.

An example of relaxers with and without de-swelling ingredients is shown in Table 3.

When cationic polyamines and starch hydrolysates are used together in hair relaxers, they leave hair visibly and measurably healthier. The tensile-strength results of hair treated with relaxer containing these ingredients vs a control without these ingredients are shown in Tables 4a and 4b.

These results indicate that the experimental group treated with relaxer containing polyamine and de-swelling ingredients exhibits a lower loss in tensile strength (M = -0.45. SD = 0.09) as compared to the control group (M = -0.57. SD = 0.10). This difference is significant at t(26) = -3.008. P < 0.006.

Figure 6 shows a scanning electron micrograph of a hair fiber treated with relaxer containing polyamine and hydrogenated starch hydrolysate. The cuticles lay flat and there are no visible cracks in the upper surface of the hair due to de-swelling.

Combing force: An exact amount (6 g) of hair relaxer without cationic polyamine was applied to 2 g of hair for 18 min. The tress was next rinsed with water and tested for ease of wet combing using a combing device set at parameters described in Table 5.

This tress was then shampooed using 1 ml of non-detangling, neutralizing shampoo and tested again for ease of wet combing using the combing device. The area under the combing curve was calculated for determining the work done in Joules to comb hair in each ease. The above experiment was repeated for the experimental hair relaxer, which contained 1.2% active cationic polyamine. The results of this experiment are shown in Table 6.

The hair relaxer containing cationic polyamine makes hair combing easy, as evident from the percent decrease in comb work shown in the last column of the Table 6.


The porosity of hair is the hair’s ability to absorb a specific amount of water. If it is chemically damaged, it absorbs more water as compared to healthy, undamaged hair. Many specialists of hair care equate the degree of damage with the magnitude of porosity of hair. One widely used method for determining porosity is described by E. I. Valko. For this study, the Valko & Barnett method, with some modifications, was used to determine porosity of hair treated with hair relaxer containing cationic polyamine and hydrogenated starch hydrolysates vs. conventionally relaxed hair and virgin hair.

For each treatment, three tresses of blended, pre-cleaned Caucasian hair were equilibrated at 21° C and 65% relative humidity for two weeks. Three tresses were treated with hair relaxer containing cationic polyamine and hydrogenated starch hydrolysate for 18 min each. These tresses were rinsed with tap water for 3 min, shampooed with acidic shampoo for 3 min and rinsed with water for 1 min. Each tress was immersed in water for 30 min and then transferred to 28 ml plastic tubes containing stainless steel mesh about 15mm above the bottom of the tube in order to keep the hair away from the drained water. They were immediately placed in a centrifuge. The parameters used for the centrifuge were RPM = 0.7 x 10.

After 20 min of centrifuging, tresses were removed from the test tubes and weighed immediately. Using the Valko & Barnett method, the percent porosity at 100% relative humidity was determined. The above experiment was repeated using control hair relaxer without cationic polyamine and starch hydrolysate. The experiment was also repeated for virgin untreated hair fibers. The results of all three types are shown in Table 7.

These results indicate that virgin hair had less porosity (M = 31.245, SD = 0.22) than hair treated with the control hair relaxer (M = 32.810, SD = 0.40). This difference is significant; t(2)= -3.28, P<0.077, two-tailed. However. hair treated with the experimental hair relaxer had the same porosity (M = 31.402, SD = 0.06) as the virgin untreated hair (M = 31.245, SD = 0.22). There is no significant difference; t(2)= -1.163, P<0.365.

Cuticle erosion:

Untreated African hair was utilized to prepare three tresses weighing 1.5 g each. The tresses were cleansed using 12.5% sodium lauryl sulfate solution and rinsed for 30 min. Tress no. 1 was designated as the untreated control; tress no. 2 was the recipient of the conventional hair relaxer without cationic polyamine and hydrogenated starch hydrolysate. It was treated with control hair relaxer for 18 min, then shampooed twice with a neutralizing shampoo and rinsed thoroughly with water. The third tress was treated with hair relaxer containing cationic polyamine and hydrogenated starch hydrolysate (experimental relaxer) for 18 min. The tress was then rinsed, shampooed twice with a neutralizing shampoo and rinsed again thoroughly with water in a manner identical to tress no. 2. All of the tresses were allowed to equilibriate at 21°C and 65% relative humidity.

Each tress was cut into small pieces and 0.3 g were weighed in 50 ml plastic disposable centrifuge tubes which were graduated. Exactly 15 ml of water were added to each tube, and samples were shaken in a shaker  at 350 rpm for 4 hr. The tubes were set parallel to the shaking platform to maximize shaking. After 4 hr, 0.5 ml of supernatant was extracted and mixed with 0.5 ml of 1.325 molar sodium hydroxide solution to dissolve the cuticles. These samples were incubated at room temperature (21° C) for 30 min.

A solution of bovin serum albumin was prepared with a concentration of 1.38 mg/ml using a spectrophotometer at 280 nm of wavelength. This standardized solution was utilized in preparing the standard curve for determination of the unknown concentrations in the supernatant.

After 30 min of incubation, 1 ml of copper carbonate solution was added and mixed into each sample. These samples were further incubated for another 15 min and 3 ml of O.2N folin-phenol reagent was added to each sample and mixed immediately. All samples were incubated for 40 min, and absorbance was read at 750 nm. From the absorbance for each
sample, the concentration of cuticle loss in each sample was determined (Table 8).

It is clear from these results that the experimental hair relaxer corrodes cuticles significantly less than the control hair relaxer.

The Conclusion

In the last 20 years, many innovations have taken place in the area of
hair relaxing and permanent waving. However, the last five years have
proven to be even more fruitful, as new innovations in this time period
have revolutionized the hair relaxing technology.

In this study, a series of cationic polyamines and starch hydrolysates have been used at various levels, separately and in combinations, to control the swelling of hair during relaxing and to enhance the strength of relaxed hair. It is now clear that during the relaxing process, hair swells to a maximum degree and the cuticle layers open widely. The cationic polyamines are able to penetrate into the cortex, and even upon rinsing hair with water, the cationic polyamines remain trapped in the cortex of the hair as the hair de-swells. They are also ionically bonded to the negative sites on the hair surface while imparting a tremendous degree of combing ease. Because cationic polyamines are elastic, the trapped cationic polyamines improve the elasticity and tensile strength of the relaxed hair fibers.

While cationic polyamines are busy penetrating the hair, the hydrogenated starch hydrolysates present in high concentration around and outside the hair fibers are able to reduce the everbuilding osmotic pressure inside the hair during the relaxing (lanthionizing) process, thereby reducing the swelling of hair fibers significantly. The major benefit of this reduction is the prevention of longitudinal and radial cracks in the hair fibers. along with a decrease in the loss of elasticity and tensile strength. Therefore, this combination of starch hydrolysates and cationic polyamines results in healthier relaxed hair.

Other benefits of simultaneous deswelling and strengthening are accrued in the form of tremendous wet and dry combing ease, reduced porosity of relaxed hair and minimal erosion of relaxed hair fiber cuticles. These new innovations have, indeed, revolutionized the relaxing of excessively curly hair by significantly decreasing the extent of damage during the relaxing process.

For more information visit  Dr. Ali Syed: In the Lab

  • […] and prone to breakage. For reasons I won’t go into here (but that others have fleshed out here and here if you’re interested), relaxed hair is prone to dryness and breakage. It’s also very […]

  • Natural Hair Diva says:

    The relaxer was not invented by Johnson in 1965. It was invented in 1913 by Garrett Augustus Morgan, the inventor of the stop light and gas mask. Please get the facts straight..

  • rozacoleman says:

    In the book:
    Hair Relaxers Science, Design, and Application
    Chapter 3
    “The Madam Walker name became synonymous with hair straightening
    and Black wealth, and she is still often credited with inventing
    the straightening comb. However, this is merely a myth according to
    Walker’s great-great-granddaughter, A’Lelia Perry Bundles, who writes in her book, On Her Own Ground: The Life and Times of Madam
    C. J. Walker, that Walker had in life denied the allegation vehemently,
    once telling a reporter, “Right here let me correct the erroneous impression
    held by some that I claim to straighten hair … I have always held
    myself out as a hair culturist. I grow hair.”

  • Roscoe says:

    Thanks for finally writing about >History of Relaxers and How Relaxers Work
    – Curly Chic <Loved it!

  • sophie says:

    “excessively curly hair “: “excessive ” in relation to what??….

    • Ellisha says:

      excessively curly hair in meaning hair with texture such as African hair type. Because tightly curly hair is international (including Asians, Indian, and South Americans) the doctor use excessively curly hair in his writings.

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