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.
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http://dx.doi.org/10.1111/j.1473-2165.2007.00294.x | DOI Listing |
J Eur Acad Dermatol Venereol
November 2019
Instituto de Assistência Médica ao Servidor Público Estadual, São Paulo, SP, Brasil.
Background: Sensory and structural characteristics of hair can be modified by chemical and physical treatments, as dyeing, brushing, but also by external factors, as sunlight radiation. However, quantitative data relating damage to the degree of hair curliness and treatments are missing.
Objective: To evaluate the effect of chemical and physical treatments on different types of hair.
An Bras Dermatol
March 2016
Instituto de Dermatologia Prof. Rubem David Azulay, Santa Casa da Misericórdia do Rio de Janeiro, Rio de Janeiro, RJ, BR.
Afro-ethnic hair is different from Caucasian and Asian hair and has unique features. Ethnic hair is more prone to certain conditions or diseases. Such diseases are not only related to the fragile inner structure of the hair, but also to the cultural habits of hairstyles that often exert traction forces upon the pilosebaceous follicle.
View Article and Find Full Text PDFSkin Res Technol
November 2009
Laboratory of Cosmetology, Department of Pharmacy, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
Background/purpose: The continuous advancement in cosmetic science has led to an increasing demand for the development of non-invasive, reliable scientific techniques directed toward claim substantiation, which is of utmost relevance, to obtain data regarding the efficacy and safety of cosmetic products.
Methods: In this work, we used the optical coherence tomography (OCT) technique to produce in vitro transversal section-images of human hair. We also compared the OCT signal before and after chemical treatment with an 18% w/w ammonium thioglycolate solution.
J Cosmet Dermatol
June 2008
Department of Pharmacy, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, SP, Brazil.
Straightening is a chemical process by which excessively curly hair is straightened in an irreversible way. Generally, products are formulated as emulsions with high pH value (9.0-12.
View Article and Find Full Text PDFJ Cosmet Dermatol
March 2007
Department of Pharmacy, School of Pharmaceutical Sciences, University of São Paulo, Conjunto das Químicas, Cidade Universitária, São Paulo, SP, Brazil.
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.
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