title: Relaxing/straightening of Afro-ethnic hair: historical overview.
abstract: Afro-ethnic hair, when compared with naturally straight hair, presents some important variations such as differences in diameter in many points of the thread, ellipsoidal threads, and low trend of hydrating the scalp thus turning the hair drier, because the natural sebum distribution is irregular along the thread. This kind of hair may be straightened through both chemical and thermal methods. Straightening is a chemical process by which excessively curly hair is straightened in an irreversible way. Generally, the products used are formulated in a cosmetic emulsion with high pH. In this review, we present the historical development of hair straightening or relaxing through the evolution of the product categories.
authors.affiliation: Department of Pharmacy, School of Pharmaceutical Sciences, University of São Paulo, Conjunto das Químicas, Cidade Universitária, São Paulo, SP, Brazil.
authors.forename: Tania Cristina
authors.initials: TC
authors.lastname: de Sá Dias
authors.forename: André Rolim
authors.initials: AR
authors.lastname: Baby
authors.forename: Telma Mary
authors.initials: TM
authors.lastname: Kaneko
authors.forename: Maria Valéria
authors.initials: MV
authors.lastname: Robles Velasco
mesh_terms: D001505:Beauty Culture / Q000266:history / Q000295:instrumentation / Q000379:methods*; D044383:Black People; D004954:Esthetics; D005260:Female; D006197:Hair / Q000737:chemistry* / Q000648:ultrastructure; D006203:Hair Preparations / Q000737:chemistry*; D049673:History, 20th Century; D006801:Humans; D008297:Male
chemical_list: D006203:Hair Preparations