REGULATIONS & TESTING
Inside hair fibre testing
High curl type hair presents the wearer with unique styling and grooming challenges. Dia-Stron explains how hair fibre metrology can provide key insights into the effects of treatments, grooming regimes and products on the properties of the hair.
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here are a variety of testing methods to choose from in the hair care industry, including salon studies, sensory panels and scientific instruments. The data from measuring physical hair fibre properties can be used to develop new hair care ingredients and technologies, as well as evaluate technical performance of new formulations and even advance hair fibre science. Scientific tests using specialised instruments provide repeatable, unbiased results. The measurement process can be automated and the environment controlled, to expand the testing capabilities. Crucially, it also produces objective data for evidence-based claims support packages, substantiating claims referring to the efficacy, benefits or improvements in hair attributes as a result of using particular hair care products or appliances.
"Scientific tests using specialised instruments provide repeatable, unbiased results“ FDAS770 loaded with a 30mm hair fibre sample
Typical stress/strain tensile curves of African hair fibres
DIFFERENCES IN HAIR TYPE Human hair can be categorised by curl type into 8 categories, with type 1 being straight or very loose waves, and type 8 being tightly coiled/crimped fibres. Hair breakage is a major concern for all consumers, but particularly for those with high curl types or who use aggressive grooming regimes/styling practices. These individual fibres are highly curled and kinked, with an elliptical cross section and significant variation along the length of the fibre. Premature breakage of high curl type fibres, occurring exclusively in the dry state at extensions often less than 20%, is attributed to the inherent structure in the twist of the fibre or flaws produced by grooming procedures. For this reason, some testing techniques are more suited to high curl type hair fibres.
TENSILE TESTING Tensile studies are perfect for investigating and assessing the performance of ingredients, treatments and products that penetrate into the hair cortex or regulate/ control the moisture of the hair. Tensile data can be used to substantiate claims such
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AUGUST 2020 // WWW.PHARMACOS.CO.ZA
Four CYC802 fatigue modules on an automation platform
Fatigue survival plots of African hair fibres
as ‘strength’, ‘damage protection’ and ‘damage repair’. The Dia-Stron Laboratory team conducted a study on hair of African origin with a curl type of 6/7. Fibre dimensional measurements were recorded on the Dia-Stron fibre dimensional analysis system (FDAS770). Specific
morphological attributes of African hair fibres can be quantified using this direct, noncontact and non-destructive technique: e.g. ellipticity ratio or cross-sectional changes along the fibre. Fibre tensile data was acquired on a miniature tensile tester (MTT690), an automated system designed to measure tensile properties of single hair fibres by stretching them to a specific percentage or to failure, in the dry or wet states. Normalising tensile data with fibre cross-sectional area reduces data variability by up to 80%. Comparing untreated (virgin) hair fibres and fibres relaxed twice using a commercially available no-lye relaxer treatment, the data indicated that hair became less stiff and more flexible as a result of applying the relaxer treatment, particularly in the wet state.
