Black women and others with curly or kinky hair encounter a vast and confusing array of hair care options. Advice on the best products to use for a specific hair type is often conflicting, and results can vary. Now, scientists are bringing order to this chaos by identifying properties such as the number of curls or coils in a given length of hair that will ultimately help users choose the perfect product and achieve consistent results.
The researchers will present their findings today at the spring meeting of the American Chemical Society (ACS). ACS Spring 2023 is a hybrid meeting held virtually and in person March 26–30.
“As an African American, I was born with very curly, seemingly unmanageable hair, and other ethnicities may have similar hair properties,” said Michelle Gaines, Ph.D., the project’s principal investigator. . Gaines used to rely on chemical relaxers to straighten her hair but stopped when she became pregnant. She then tackles a wide variety of products that can be used to style and care for natural hair. Limited guidance on the best options for her particular hair type, and conflicting advice from friends, YouTube videos and other resources, didn’t help the situation.
Clearly, Gaines says, there is a huge knowledge gap that needs to be closed, so he sets out to fill it. “As a polymer chemist and materials scientist, I thought it would be good to start a project where I could study the nuances of my hair, because I felt it was not well understood,” he said.
Most of the early research on the properties was done on wavy or straight strands from white or Asian people, according to Gaines, who is at Spelman College, a historically Black college for women. Not much is known about what is traditionally called “African” hair, he said, although researchers at Groote Schuur Hospital and the University of Cape Town in South Africa have published some findings.
L’Oréal, as well as celebrity hair stylist Andre Walker and others, have developed systems to classify different types of hair. Walker’s system ranges from straight to kinky, a category that includes tight coils and zig-zag strands with angular bends. Although some people believe that all of these classification methods give rise to a preference for a neater and straighter look—a bias that has historical links to the preferential treatment of enslaved people with straighter hair and lighter skin—they are intended to help users choose the most suitable. hair care products. Gaines feels these systems work well for straight and curly hair but lack the nuance to distinguish many types of curly and curly hair.
Gaines wanted to see if he could identify differences in properties other than curl shape and tightness, and then use those differences to create a more accurate and quantitative classification system. Spelman undergraduates eagerly lined up to help. Gaines and his student, Imani Page, collaborated with Alfred Crosby, Ph.D., and Gregory Grason, Ph.D., at the University of Massachusetts Amherst; their expertise includes characterizing material properties and modeling complex materials and soft objects.
The team measured the mechanical properties of wavy, curly and curly hair using a texture analyzer and a dynamic mechanical analyzer. These instruments measure force, stress and other parameters as a strand is first broken and then stretched until it breaks.
Among other findings, the team recently reported results for the “stretch ratio,” a new parameter they developed to quantify and compare the force required to uncurl the a strand until it is straightened. That ratio was found to be less for straight hair (because it doesn’t break), about 0.8 for wavy, 1.1 for kinky and 1.4 for curly. This measurement can be used as an indicator of the initial curl of a sample, providing a quantitative way to distinguish between these types.
The team also measured the geometric properties, such as the diameter, cross section and 3D shape of the strands, using optical microscopy, scanning electron microscopy (SEM) and a camera. In addition, the researchers developed new parameters, including the number of complete waves, curls or coils—known as contours—that they measured in a 3-cm length of hair. They found that curly hair has less than one full contour at that length, curly has about two, and kinky/coily has approximately three or more. The results suggest that people are able to classify their own hair by counting the contours, Gaines said.
In the latest work, Gaines began examining the layer that protects the surface of each hair fiber. Known as the cuticle, it consists of flat cells that overlap each other, like roof shingles. Cuticles have a natural tendency to open and close which is reversed when exposed to water, shampoo and conditioner. However, excessive retention of acid and moisture can cause permanent damage to the cuticles, causing them to remain unchanged, thus exposing the inner cortex of the hair fiber. Unretractable cuticles, and cuticles that open and close easily, make the strand more porous, which causes more moisture absorption. Gaines’ preliminary findings show that the cuticle layers are larger and spaced further apart in wavy hair than in curly and coily hair. In addition, the edges of the cuticle are smoother on curly hair. These findings help researchers explain why curly and coily locks dry out faster than curly and straight hair. Ultimately, Gaines hopes, the team’s findings will identify the best parameters for developers to design and for consumers to choose the most appropriate products for each of the amazing variety hair categories.
ACS Spring 2023: Reimagining hair science: A new approach to classify curly hair phenotypes through new quantitative geometrical & structural mechanical parameters, www.acs.org/meetings/acs-meetings/spring-2023.html
Provided by the American Chemical Society
Citation: New ways to measure curls and kinks make natural hair care easier (2023, March 26) retrieved on July 6, 2023 from https://phys.org/news/ 2023-03-ways-kinks-easier-natural-hair.html
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