In 2000, I co-authored an article for C&T magazine regarding the scalp irritation potential of lye and no-lye relaxers. The article includes our findings from a study based on comfort/discomfort evaluations from salon patrons.
Compared to Caucasian hair, African-American hair is extremely curly and it's physical configuration resembles a twisted ribbon. It is highly unmanageable. very difficult to comb-both wet and dry-and hard to style. More fragile than Caucasian hair, this excessively curly hair breaks more easily when stretched or vigorously brushed and combed. Thus, African-American hair requires both special handling and hair-care products that are differently formulated than those for Caucasian hair.
Madam C. J. Walker: A Beauty Product Pioneer
Madam C. J. Walker was an early 20th century beauty product pioneer. She was born under the name Sarah Breedlove to ex-slaves in 1867. In her early life, she worked in both the cotton fields and the kitchen. In 1905, after marrying newspaper sales agent Charles Joseph Walker, she adopted his name and developed expertise in manufacturing hair goods and preparations.
Walker soon launched her own business, designing cosmetics and hair-care products for black women. From this business she became one of the nation's first female millionaires. Using her success for the good of others, she earned a reputation as a philanthropist to African-American institutions such as the NAACP, Tuskegee Institute and Bethune-Cookman College. She died in 1919.
In 1998, the US Postal Service issued a stamp commemorating her achievement as an African-American businesswoman and philanthropist. The image on the stamp is from a circa 1914 photo that was used extensively by Walker's company for publicity purposes, in advertising, and on its products.
The Development of Relaxers
In the early 1900s, an African-American domestic worker, later known as Madam C. J. Walker, invented pomade using a combination of oils (see sidebar). This pomade revolutionized the hairstyling practices of African-American women and made excessively curly hair softer, shinier and somewhat easier to comb. However, the pomade did not straighten the hair. African-American women still could not achieve styles like those worn by Caucasian women.
In 1905, Madam Walker invented a straightening comb to address this need. This comb could be heated on the stove and used in conjunction with her pomade. Such treatment left the hair shiny, silky, and temporarily straight. This method became known as the Walker Method and was later referred to as "hair pressing."
Lye relaxers: Until the 1950s, the problems of extremely curly hair were not fully addressed by the existing hair-care businesses because of a technology void. This changed in 1965. when an innovative permanent hair straightener for African-American consumers was introduced. Its active ingredient was sodium hydroxide, or lye. This chemical method for relaxing the hair eliminated the need for temporary hair straightening by the Walker Method.
The relative advantages of chemical hair straightening over the Walker Method were numerous, and the adoption of permanent hair straightening advanced rapidly. This innovation had social ramifications as well. For the first time, African-American women could wear the styles that dominated the American culture. Sales of relaxers soon became viable products in the industry.
Competitive forces began to address the weaknesses of this first-generation relaxer cream in the late 1960s. The first generation relaxers tended to overprocess hair and diminish its strength. They irritated the scalp and were difficult to rinse out of the hair. They also had a short shelf life because the oil and water phases present in the relaxer cream tended to separate with time. Upon separation of the cream, the water-soluble sodium hydroxide was present only in the water phase, resulting in inconsistent straightening of the hair.
Texturizing relaxers: In 1971, a relaxer cream called a texturizing relaxer was introduced. It addressed some of the above-mentioned concerns. This cream was more stable in hot and cold temperatures and provided slightly more scalp comfort by being less irritating. This relaxer cream straightened hair slightly less than the previous relaxer, but it was more acceptable to hair stylists and consumers because of its relatively greater comfort potential and better stability between room temperature and 45°C. Formula 1 shows a prototype of this relaxer.
Over the years, more and more hair stylists started to use texturizing cream relaxers. This product has became a benchmark in the African-American hair-care industry. A benchmark product is one that is superior in its attributes, quality, cost, and performance and has been used by consumers for a long lime.
No-Lye relaxers: Because of the high irritation potential of texturizing cream relaxers containing sodium hydroxide as an active ingredient, efforts were underway to formulate relaxers that possessed less irritation potential to the scalp. In 1978, a patented two-component cream relaxer, formulated with the active ingredient guanidine hydroxide, was introduced to the marketplace as a 'no-lye' relaxer with claims that it was less irritating to the scalp. Mixing a cream containing calcium hydroxide with a liquid activator containing guanidine carbonate produced the guanidine hydroxide. Formula 2 shows a prototype of this relaxer.
In 1997, Syed mentioned that no-lye relaxers have significantly less irritation potential than lye relaxers containing sodium hydroxide as an active ingredient. Amin et al. (1998) have also mentioned that no-lye relaxers are milder to the scalp than lye relaxers containing sodium hydroxide. However, none of these authors cites references on this subject.
De la Guardia compared guanidine relaxer of his invention to a commercially available relaxer containing sodium hydroxide. After applying the two formulations to the skin of rabbits, he concluded that guanidine hydroxide relaxer did not produce irritation. On the other hand, the sodium hydroxide based relaxer resulted in minor to severe irritation at various treatment times. However, to the best of our knowledge, there is no study in existence that compares the irritation potential of lye relaxers against that of no-Iye
relaxers on the scalp of human subjects.
The Irritation Potential of Relaxers
It is pertinent to discuss what we mean by irritation here. Malten in 1981 described irritation as irritant contact dermatitis that is localized, superficial, exudative, nonimmunological inflammation of the skin or scalp due to the direct influence of one or more external factors. Pieter, van der Valk and Tupker believe that, in general, symptoms arrive quickly after the exposure and heal steadily.
The relaxers are considered as cosmetics products. Generally, they may cause a stinging, itching or burning sensation during their application. If a patron experiences a severe stinging that is unbearable, it is recommended that a relaxer cream be rinsed off from the scalp using tepid tap water followed by an acidic shampoo. It is known in the trade that improperly formulated lye relaxers can cause severe scalp irritation and chemical burns. This type of irritation is called sensory irritation or subjective irritation. Although the mechanisms by which materials produce sensory or subjective irritation are not yet completely known, Maibach and Johnson have presented some possible mechanisms for this type of irritation.
It is our observation that the application of relaxers may cause sensory complaints of stinging, itching or burning to the scalp, and that these complaints go away after rinsing the relaxer. This irritation is localized and does not spread to the other parts of the
scalp and skin. Therefore, it is probably safe to say that irritation induced by lye and no-lye relaxers is nonimmunological.
Many attempts have been made to use colorimeters on African-American skin to measure erythema, a principal sign of irritation on white skin. This technique fails to produce reliable results on African-American skin due to its darker natural pigmentation. An alternative method may be the use of a laser blood flow measuring device, but so far there is no significant scientific work cited in this area.
Lacking complete knowledge about the mechanisms by which materials produce sensory irritation, and unable to use the erythema test on African-American skin, we decided to use comfort/discomfort evaluations from our salon patrons as markers of relaxer irritation potential.
Comparing Relaxers' Irritation Potential
Purpose of the study: From patrons in our salon, we obtained comfort/discomfort evaluations as indications of the irritation potential of lye and no-lye relaxer creams at two different strengths. We applied the creams to the scalps of 1103 Chicago area African-American individuals with excessively curly hair over a five-year period.
The lye relaxer (Formula 1) contained sodium hydroxide as an active ingredient. For the no-lye relaxer (Formula 2), guanidine hydroxide was the active ingredient. Each relaxer was formulated twice: at a "normal" strength and at a "resistant" strength.
The comfort-discomfort response was measured using the five-point Likert scale at each relaxer treatment. Simultaneously, trained salon technicians evaluated the scalp before and after each treatment to observe any scalp fissuring, scalp burns and scalp erythema.
The purpose of this study was to compare the irritation potential of the no-lye relaxer against that or a lye relaxer. It was also important to measure the degree of comfort or discomfort for each relaxer category for benchmarking purposes. More specifically, this study attempted to verify the following hypotheses:
1. The irritation potential of a no-lye cream relaxer containing guanidine hydroxide as an active ingredient is significantly less than that of a lye cream relaxer containing sodium hydroxide as an active ingredient at a constant degree of straightening.
2, The no-lye cream relaxer imparts significantly less 'severe', 'moderate', 'mild', and 'minor' irritation as compared to the lye relaxer.
The significance of this study is that it serves as the starting point or baseline measurement of irritation potential of present relaxer creams and thus serves as a benchmark for the future studies for formulating less irritating relaxer creams.
Experimental procedure: Two strengths of lye relaxer were prepared and labeled "normal" and "resistant" based on their concentration of sodium hydroxide. Similarly, two strengths of no-lye relaxer with guanidine hydroxide were prepared and labeled. In all comparisons, the two relaxer types were of equivalent strengths; that is, both were normal strength or both were resistant strength.
The individuals who took part in this study had excessively curly hair and ranged in age from 18 to 65 years. Each individual was given a treatment of a specific strength lye relaxer (n = 513) or no-lye relaxer (n = 590) for a specified time of 13 to 18 min depending upon the texture of the individual's hair. For an individual with medium-textured hair, the preferred treatment was a normal strength relaxer for 15 min. For an individual with coarse-textured hair, the preferred treatment was a resistant strength relaxer for 18 min.
The hair stylists were first trained in the application of these relaxers and the application technique used in this study was very similar for both relaxers. A petrolatum jelly was applied to the hairline and ears for protection, and the hair was parted into four equal parts from the middle of the forehead and then from ear to ear. The cream relaxer was applied to the virgin portion of the hair only, first to the back section using a soft small brush or a rattail comb and then worked through the next sections in a clockwise direction.
Once the application was complete, which took an average of 8 min, the cream was smoothed with the back of the rattail comb, section by section, to achieve the desired degree of straightening before rinsing the hair thoroughly with tepid tap water.
At the end of the treatment time, the relaxer was rinsed with water, and then conditioned with a standard conditioner of pH 5.0 containing cationic polymers and quaternary ammonium chlorides for 5 min. The hair was then shampooed using standard neutralizing shampoo and evaluated.
Evaluation: The hair was evaluated for various attributes such as degree of straightening and the patron's perception of comfort or discomfort level. Figure 1 shows the questionnaire used in evaluating irritation potential and straightening of hair. This questionnaire records the patron's impression of the comfort or discomfort (irritation) imparted by the relaxer during its application. The following five-point likert scale was used by each patron to rate the comfort level of the relaxer:
1 = Severe irritation
2 = Moderate irritation
3 = Mild irritation
4 = Minor irritation
5 = Very comfortable
The discomfort was associated with the irritation potential of the relaxer. The highest form of discomfort was severe irritation and the lowest form of discomfort was considered to be the minor irritation. A patron response indicating that there was no irritation during the relaxer process was recorded as very comfortable.
Results and Discussion
Comparing average comfort scores: When the relaxers were compared at normal strength as shown in Table 1, the average comfort scores were 4.90 for no-lye relaxer and 4.55 for lye relaxer. The difference in the groups is statistically significant at a p value of less than 0.00. Therefore, it is evident that at normal strength, the no-lye relaxer is significantly more comfortable to the scalp during relaxer treatment than the lye relaxer.
When the relaxers were compared at resistant strength as shown in Table 2, the average comfort scores were 4.94 for no-lye relaxer and 4.57 for lye relaxers. The difference in the groups is statistically significant at a p value of less than 0.00. Therefore, it is evident that at resistant strength the no-lye relaxer is significantly more comfortable to the scalp during relaxer treatment than the lye relaxer.
Comparing the average straightening ability scores:
As shown in Table 3, at normal strength, the relaxers showed average straightening ability scores of 4.31 for the no-lye relaxer and 4.10 for the lye relaxer. Therefore, a no-lye relaxer is significantly better in its straightening ability at a p value of less than 0.00. Even then, the no-lye relaxer is less irritating than a lye relaxer.
As shown in Table 4, at resistant strength, the relaxers showed average straightening ability scores of 4.17 for the no-lye relaxer and 4.26 for the lye relaxer. With a p value of less than 0.56, there is no significant difference in the straightening ability of these two formulas. Although, they are equal in their straightening qualities at resistant strength, the no-lye relaxer is less irritating to the human scalp than the lye relaxer.
Irritation Index: For each relaxer and its irritation evaluation scores, we calculated an irritation index based on the following equation:
Irritation Index = (MPSC - ASC) / MPSC x 100
where MPSC = maximum possible scalp comfort score
ASC = average scalp comfort score
The maximum possible scalp comfort score is always 5.0. The average scalp comfort score is the response of the patron about a relaxer's comfort or irritation level. From the irritation potential scores in Tables 1 and 2, we obtained the irritation indices shown in Table 5. For example, the average scalp comfort score for normal strength lye relaxer is 4.55 from Table 1 column 1; therefore, the irritation index will be calculated as (5.00 - 4.55) / 5.00 x 100 = 9.00.
It is obvious from these indices that no-lye normal and resistant formulas have the smallest irritation indices. They are therefore, least irritating to the scalp and the salon patrons are more comfortable during the treatment with these two relaxers. On the other hand, lye relaxers show a very high irritation index and are significantly more prone to irritate the scalp of salon patrons. Ideally, formulating chemists should try to lower the irritation index of a given formula to as close to zero as possible. Therefore, this technique may prove to be of some help to the formulating chemists when testing the irritation index of a relaxer in the R&D testing salon.
Irritation levels for each relaxer type: At normal strength, the lye relaxer tends to impart irritation in 20.30% of the patrons while a no-lye relaxer imparts irritation to 5.40% of the patrons (Table 6). Similarly, at resistant strength the lye relaxer tends to impart irritation in 13.60% of patrons while the no-lye relaxer imparts irritation to 2.90% of the patrons (Table 7).
Severity of irritation in lye relaxers is significantly higher than in no-lye relaxers, as shown in Tables 6 and 7 and in Figures 2 and 3. The lye relaxer (normal) imparts severe, moderate, mild, and minor irritation in 1.33%, 6.67%, 7.2%, and 5.1% of patrons respectively. Similarly, the no-lye relaxer (normal) imparts severe, moderate, mild, and minor irritation to 0.83%, 0%, 2.1%, and 2.5% of the population. It is clear from Figures 2 and 3 that no-lye relaxers are considerably gentler the scalp compared to lye relaxers.
Conclusion
No·lye relaxers show significantly less scalp irritation than lye relaxers, regardless of whether the irritation is rated as severe, moderate, mild or minor. Therefore, the no-lye relaxer is most suitable for individuals of African descent or for individuals with excessively curly hair and sensitive scalp.
No·lye relaxers keep the scalp comfortable 95-97% of the time while lye relaxers are able to keep the scalp comfortable only 80-83% of the lime. We suggest that these ranges become a guide in testing the relaxers in the laboratory or in the marketplace to gauge a relaxer's acceptance in terms of its irritation potential to the scalp.
We believe that this study is the first salon study that compares the irritation potential of lye relaxers against no-lye relaxers. It could become a benchmark for the industry to develop newer, low irritation or non-irritation relaxers.
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