Results tagged “caucasian”

Static Charge of Hair

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One thing to remember when dealing with different hair types is the susceptibility to carry electrostatic charges. Generally speaking, untreated African descent hair develops a highly negative electrostatic charge (-25.4 KV/m), but in contrast, Caucasian hair develops a very low positive electrostatic charge (+6.6 KV/m).

The relatively high negative charge acquired by dry African descent hair during combing may be due to the extraordinarily high degree of pulling force required to pass the comb through the mass of entangled hair fibers. This relatively high electrostatic charge produces a "balloon effect" and contributes to a higher degree of hair unmanageability.


Sources: 

Syed, A.N., Kuhajda, A., Ayoub, H., Ahmad, K., and Frank, E. (1995). African American Hair: Its physical properties and differences relative to Caucasian hair. Cosmetics & Toiletries Magazine. 110:46

Robbins, C.R. (1994). The physical properties and cosmetic behavior of hair. In Chemical and Physical Behavior of Human Hair. New York: Springer-Verlag, p.348

Moisture in Hair

moisture.gif A common topic that I hear about in my conversations with hair stylists and salon patrons is about moisture. What I usually tell people is that the moisture in African descent hair is significantly less than in Caucasian and Oriental (i.e. Mongol descent) hair.

One reason for such deficiency of moisture could be the twisted ribbon-like structure of the African descent hair. The other reason for the deficiency of the moisture in African descent could be that the sebaceous glands within the African scalp are often less active and secrete inadequate amounts of sebum--the body's own natural brand of conditioner and hair-dress.

Therefore, the hair and scalp are relatively dry because there is less natural oil to be distributed down the hair shaft. Also, whatever oil that is secreted may find it harder to travel down the hair shaft because of the strands' excessive curliness, thus further contributing to dryness. The lower moisture contents of African descent hair may be a significant contributor to its relative fragility and will require future research.

Contrarily, Caucasians tend to have hyperactive sebaceous glands, hence the widespread practice of daily shampooing and the usage of stronger shampoos that contain less conditioning agents.
African American Hair
View SlideShare document or Upload your own. (tags: african american)


Here's a study that I helped author in 1995 regarding the physical properties of African American hair and how it differs from Caucasian hair. Enjoy.

Scientific innovations in chemical treatments that alter the texture of African-American hair, as well as a plethora of style trends, have spurred phenomenal growth in this
segment of the hair-care market throughout the past three decades. The level of research & development by manufacturers in the area of product formulation has steadily elevated; yet, a great deal remains to be learned about the unique physical properties of African American hair. Compared to the vast body of research regarding Caucasian hair, the study of African-American hair is at best limited.


A Review of Research

In published studies, J. Menkart et al, Epps et al and Kamath et al reveal that some important research has indeed been conducted on the physical properties of highly curly hair. The efforts of these researchers and the results of their studies serve as a starting point for the further study of African-American hair. Other general observations about hair, such as those pertaining to static charge (Jachowicz and C.R. Robbins) and theories about moisture content, serve as a springboard for advancing the study of African American hair.

Shape: Menkart and Wolfram report that African-American hair has a physical shape resembling a twisted oval rod, whereas Caucasian hair is more cylindrical. They found evidence of this when they made elliptic comparisons or hair cross-sections. Using a formula in which the minor axis is divided by the major axis, Menkart and Wolfram
determined that African-American hair has a ellipticity index of 0.56 and Caucasian hair has an index or 0.7.1. The tensile-strength data gathered during this research shows that the breaking stress of African·American hair (1.24 g/denier, a unit of fineness equal to the fineness of a yarn weighing 0.05g for each 450m of length or 19 for each 9000m.) is less than that of Caucasian hair (1.41 g/denier). The yield stress for African-American hair, however, is slightly higher (0.46 g/denier VS 0.42 g/denier).

Kamath and Hornby studied the fractographic behavior of African-American hair to view both major and minor rods at low levels of extension. They examined the ellipticity of
hair fibers and reported ellipticity indices of 1.89±0.083 and 1.0 to 1.4 for African-American and Caucasian hair, respectively. In this study, the ellipticity index was calculated by dividing the major axis by the minor axis, which is the reverse of the formula used by Menkart and Wolfram.

Combability: Epps and Wolfram conducted combing comparisons between African-American and Caucasian hair using combability techniques used by Garcia and Diaz. Garcia and Diaz report that African-American hair, due to its curliness, is much more difficult to comb than Caucasian hair. It was also determined that African-American hair is easier to comb wet than dry.

Using a scanning electron microscope at a magnification of about 300X, Kamath and Hornby also observed that African American hair display frequent twists with random reversals in direction and pronounced flattening. During fractographic study, the break stress of African-American hair was reported to be (0.123 ± 0.016) 10^9 N/m^2 when dry (65% relative humidity [RH]) and (0.119 ± 0.010) 10^9 N/m^2 when wet. The breaking elongation for wet and dry (65% RH) fibers was found to be 44% ±3% and 27% ± 5%, respectively.

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