MSGID: 1:317/3 64226d6e   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    New ways to measure curls and kinks could make it easier to care for   
   natural hair    
      
     Date:   
         March 27, 2023   
     Source:   
         American Chemical Society   
     Summary:   
         Black women and others with curly or kinky hair encounter a   
         confusing array of haircare options. Advice on the best products   
         to use for a certain type of hair is often contradictory, and the   
         results can be highly variable. Now, scientists are bringing order   
         to this chaos by identifying hair properties that could help users   
         pick the perfect product and achieve consistent results.   
      
      
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   FULL STORY   
   ==========================================================================   
   Black women and others with curly or kinky hair encounter a vast and   
   confusing array of haircare options. Advice on the best products to use   
   for a certain type of hair is often contradictory, and the results can   
   be highly variable.   
      
   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 could   
   eventually help users pick the perfect product and achieve consistent   
   results.   
      
      
   ==========================================================================   
   The researchers will present their findings today at the spring meeting   
   of the American Chemical Society (ACS).   
      
   "As an African American, I was born with very curly, seemingly   
   unmanageable hair, and other ethnicities can possess similar hair   
   properties," says Michelle Gaines, Ph.D., the project's principal   
   investigator. Gaines used to rely on chemical relaxers to straighten her   
   tresses but stopped when she became pregnant. She was then confronted   
   with an overwhelming variety of products available to style and care for   
   natural hair. Limited guidance about 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 major knowledge gap that needs to be   
   closed, so she has set out to fill it. "As a polymer chemist and materials   
   scientist, I thought it would be great to start a project where I could   
   study the nuances of my hair, because I felt like it wasn't very well   
   understood," she says.   
      
   Most prior research on 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. Less is known about   
   what has traditionally been called "African" hair, she says, though   
   researchers at Groote Schuur Hospital and the University of Cape Town   
   in South Africa have published some findings.   
      
   L'Ore'al, 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 including tight coils   
   and zig-zag strands with angular bends. Although some people believe all   
   of these classification methods convey a preference for a smoother and   
   straighter appearance -- a bias with historic links to the preferential   
   treatment of enslaved people who had straighter hair and lighter skin   
   -- they're intended to help users choose the most suitable haircare   
   products. Gaines felt these systems worked well for straight and wavy   
   hair but lacked the nuance to distinguish the many varieties of curly   
   and kinky hair.   
      
   Gaines wanted to see if she could identify differences in properties other   
   than curl shape and tightness, and then use those differences to develop   
   a more precise and quantitative classification system. Undergraduates   
   at Spelman eagerly lined up to help. Gaines and her student, Imani Page,   
   are collaborating with Alfred Crosby, Ph.D., and Gregory Grason, Ph.D.,   
   at the University of Massachusetts Amherst; their expertise includes   
   material property characterization and modeling of complex materials   
   and soft matter.   
      
   The team measured the mechanical properties of wavy, curly and kinky   
   hairs with a texture analyzer and a dynamic mechanical analyzer. These   
   instruments measure force, stress and other parameters as a strand is   
   first uncurled 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 a strand until it's straight. That ratio was found   
   to be negligible for straight hair (since it can't be uncurled), about   
   0.8 for wavy, 1.1 for kinky and 1.4 for curly. This measurement could   
   therefore be used as an indicator of the initial curliness of a sample,   
   providing a quantifiable way to distinguish between these types.   
      
   The team also measured geometric properties, such as the diameter, cross   
   section and 3D shape of 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 on 3-cm lengths of   
   hair. They found that wavy hair has less than one full contour in that   
   length, curly has about two, and kinky/coily has approximately three   
   or more. The results suggest that people will be able to classify their   
   own hair by counting contours, Gaines says.   
      
   In the latest work, Gaines has begun 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 reversibly when exposed to water,   
   shampoo and conditioner.   
      
   However, excessive acid and moisture retention can cause permanent damage   
   to the cuticles, causing them to remain irreversibly lifted, thus exposing   
   the inner cortex of the hair fiber. Irreversibly lifted cuticles, and   
   cuticles that easily open and close, make the strand more porous, which   
   causes more moisture absorption. Gaines' preliminary findings show the   
   cuticle layers are larger and spaced further apart in wavy hair than   
   in curly and coily hair. Also, the cuticle edges are smoother in wavy   
   hair. These findings could help the researchers explain why curly and   
   coily locks dry out faster than wavy and straight tresses. Ultimately,   
   Gaines hopes, the team's findings will identify the best parameters   
   for developers to design and for consumers to select the most suitable   
   products for each of the wondrously varied categories of hair.   
      
   The researchers acknowledge support from the University of Massachusetts   
   Amherst.   
      
       * RELATED_TOPICS   
             o Matter_&_Energy   
                   # Nanotechnology # Materials_Science   
                   # Textiles_and_Clothing # Spintronics #   
                   Engineering_and_Construction # Inorganic_Chemistry #   
                   Chemistry # Thermodynamics   
       * RELATED_TERMS   
             o Carbon_nanotube o Mica o Scientific_method o Atom o   
             Polyethylene o Black_body o Trans_fat o Engineering   
      
   ==========================================================================   
   Story Source: Materials provided by American_Chemical_Society. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
      
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230327114914.htm   
      
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