Hair Straightening: Techniques, Chemicals, and Evolution

March 2010 in “ Cosmetic Dermatology ”

Harold Bryant PhD Assistant Vice President, Felicia A. Dixon, Angela Ellington Assistant Vice President and, Crystal Porter

ammonium thioglycolate sulfites hydroxide thermal appliances flat irons chemical straighteners sodium hydroxide no-base relaxers no-lye relaxers hair proteins cuticle erosion conditioning lye relaxers

Studysummary Hair straightening methods have advanced to improve effectiveness and reduce damage, but still rely on heat and chemicals.

Our plain-language summary. Not medical advice or a treatment recommendation. Consult a qualified healthcare professional before changing treatment. Full disclaimer

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Research cited in this study

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research Shape Variability and Classification of Human Hair: A Worldwide Approach

95 citations , January 2007 in “Human biology”

This study proposes a new, objective method to classify human hair into eight categories based on specific shape measurements, rather than traditional ethnicity-based classifications.

research Diversity of Hair Growth Profiles

115 citations , September 2005 in “International Journal of Dermatology”

Different ethnic groups have unique hair growth patterns, with African hair growing slower and less dense, Asian hair growing fast but sparse, and Caucasian hair being densest; men are more likely to experience hair loss than women.

research Ceramide Binding to African-American Hair Fiber Correlates with Resistance to Hair Breakage

45 citations , February 2002 in “International Journal of Cosmetic Science”

This study found that a ceramide derived from sphinganine can bind to African–American hair, reducing breakage when applied in a shampoo after relaxing treatments.

research Mechanism of Hair Straightening

10 citations , January 1994

This study discusses that permanent hair straightening can be achieved at neutral or acidic pH conditions, with varying effects on cystine and lanthionine levels, by inducing supercontraction of the hair fiber.

research Action of Nucleophilic Reagents on Hair Keratin

9 citations , January 1981

This study found that the alkaline degradation process of hair keratin using nucleophilic reagents led to different proportions of reaction products compared to wool, particularly more lanthionine and lysinoalanine residues.