Hair Ethnicity and Ellipticity: A Preliminary Study

Apr 1, 2013 | Contact Author | By: Ali N. Syed, PhD; Tomas N. Ventura Jr.; and Maliha N. Syed, Avlon Industries Inc.
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Title: Hair Ethnicity and Ellipticity: A Preliminary Study
ellipticityx major and minor axisx ethnic hairx elasticityx stress/strainx
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Keywords: ellipticity | major and minor axis | ethnic hair | elasticity | stress/strain

Abstract: Ethnic hair care addresses diverse fiber compositions that require unique products. This comprehensive review in hair fiber dimensions among straight, wavy and curly/coily hair serves as a basis from which product developers can design products to cater to unique hair type needs. The current study examines the ellipticity of Caucasian, Brazilian, Hispanic and African-American hair.

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AN Syed, TN Ventura and MN Syed, Hair Ethnicity and Ellipticity: A Preliminary Study, Cosmet & Toil 128(4) 250 (2013)

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Recently, the hair care industry has taken interest in targeting products according to ethnic demographics, to respond to unique needs. In the U.S., ethnic hair products are sold in designated areas of retail stores to make the process of finding appropriate niche products more convenient. Moreover, this has initiated a discussion regarding which hair types fall under the umbrella of “es typically quite wavy or curly as well.1

Beneath the ethnic hair umbrella are various ethnicities that present diverse hair fiber compositions, which require unique products. For example, straightening pthnic.” For example, again in the U.S., ethnic hair refers to hair of African or Hispanic descent that is very curly. Central American and South American hair types, e.g., Brazilian, Colombian, Venezuelan, etc., also could be included, as hair from these descents iroducts based upon guanidine hydroxide, sodium hydroxide and ammonium thioglycolate are frequently used to straighten African-American, Brazilian, Colombian, Venezuelan and Hispanic hair having wavy or very curly textures. Similarly, shampoos with 1% to 1.50% levels of cationic polymers are used to cleanse and detangle wavy/very curly hair. Such detangling shampoos, if used daily on straight Caucasian hair, will leave a polymeric residue buildup. Thus, a comprehensive review of the differences in hair fiber dimensions among straight, wavy and curly/coily hair is necessary to guide formulators as they develop products that cater to unique hair type needs.

Fiber Diameter vs. Shape

In the literature, hair fiber diameter has been identified as the distinguishing factor to classify fibers as fine, medium or coarse. Assuming the hair fiber is cylindrical in shape, this system remains appropriate across a variety of populations. Asian or Oriental and straight Caucasian hair, for example, tend to be more cylindrical.

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This content is adapted from an article in GCI Magazine. The original version can be found here.

 

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Table 1. Kruskal-Wallis Test

Table 1. Kruskal-Wallis Test

The CV of various ethnic groups was ranked as shown in Table 1 using the Kruskal–Wallis test.

Table 2. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity of multiple fibers of a Caucasian individual (hair batch 1)

Table 2. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity  of multiple fibers of a Caucasian individual (hair batch 1)

For example, the ellipticities of five Caucasian fibers from a single batch fall into two significant sub-groups, at p < 0.05 (see Table 2).

Table 3. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity of multiple fibers of a Brazilian individual (EV)

Table 3. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity of multiple fibers  of a Brazilian individual (EV)

The ellipticities of five fibers of a Brazilian individual fall into four subgroups, at p < 0.05, as shown in Table 3.

Table 5. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity of multiple fibers of an African-American individual (DD)

Table 5. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity of multiple fibers  of an African-American individual (DD)

Similar to the fibers of a Brazilian individual, the ellipticities of five fibers of an African-American individual fall into four subgroups, at p < 0.05, as shown in Table 5.

Table 4. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity of multiple fibers of a Hispanic individual (OR)

Table 4. Analysis of Variance (ANOVA—Tukey HSD) of ellipticity of multiple fibers  of a Hispanic individual (OR)

Further, the ellipticity of five fibers of a Hispanic individual fall into three distinct subsets, at p < 0.05, as shown in Table 4.

Table 6. ANOVA—Tukey B test fibers of various ethnicities

Table 6. ANOVA—Tukey B test fibers of various ethnicities

The Brazilian fibers had the highest average ellipticity as shown in Table 6, Tukey HSD, Subset 4, followed by African-American fibers in Subset 3.

Figure 1. Ellipticity of hair

Figure 1. Ellipticity of hair

The ellipticity of a hair fiber is defined as the ratio of the diameter of the major axis to the minor axis3 (see Figure 1), and this been found to correlate to other fiber properties such as elasticity and ease of combing.

Figure 3. Images of the Caucasian hair tresses tested

Figure 3. Images of the Caucasian hair tresses tested

The Caucasian fibers were straight, whereas Brazilian and Hispanic fibers were wavy, and African-American fibers were very curly and coily in shape (see Figures 3–6).

Figure 4. Images of the Brazilian hair tresses tested

Figure 4. Images of the Brazilian hair tresses tested

The Caucasian fibers were straight, whereas Brazilian and Hispanic fibers were wavy, and African-American fibers were very curly and coily in shape (see Figures 3-6).

Figure 2. Schematic of the laser micrometer for measuring X and Y axis of hair fiber

Figure 2. Schematic of the laser micrometer for measuring X and Y axis of hair fiber

A schematic diagram of the laser micrometer and load cell assembly is shown in Figure 2.

Figure 5. Images of the Hispanic hair tresses tested

Figure 5. Images of the Hispanic hair tresses tested

The Caucasian fibers were straight, whereas Brazilian and Hispanic fibers were wavy, and African-American fibers were very curly and coily in shape (see Figures 3–6).

Figure 6. Images of the African-American hair tresses tested

Figure 6. Images of the African-American hair tresses tested

The Caucasian fibers were straight, whereas Brazilian and Hispanic fibers were wavy, and African-American fibers were very curly and coily in shape (see Figures 3–6).

Figure 7. African-American (CM1) hair fiber diameter per data point (100 pts), displaying major and minor axis variations

Figure 7. African-American (CM1) hair fiber diameter per data point (100 pts), displaying major and minor axis variations

An abbreviated table showing just 100 data points from one African-American hair fiber donor (CM) is shown in Figure 7.

Figure 8. The CV of fibers of various ethnic groups

Figure 8. The CV of fibers of various ethnic groups

Upon further analysis of ellipticity variation within a fiber, the CV was calculated for each ethnic group (see Figure 8).

Figure 9. Ellipticity variation for a single hair fiber for Caucasian, Brazilian, Hispanic and African-American hair

Figure 9. Ellipticity variation for a single hair fiber for Caucasian, Brazilian, Hispanic and African-American hair

The scan of actual ellipticities of fibers for each ethnic group across fiber length are shown in Figure 9.

Footnotes (Syed)

a The Tracer IT 5000 S/N 135 is a device from Zimmer KG Rossdorf.
b Samples were obtained from IMHair, Italy, and c DeMeo Brothers, NJ, USA.
d CM refers to the initials of the sample donor, and 1 indicates fiber 1.

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