Assessing the effect of cleansing products on artificially polluted human hairs and skin through in vivo and in vitro models.

OBJECTIVE: Based on in vivo data, in vitro models and new methods are created to mimic the impact of aerial pollution onto the hair surface and assess the efficacy of different formulae prototypes. MATERIAL AND METHODS: Two protocols are developed to mimic the pollution effect, in vitro, on purchased swatches, and in vivo, on scalps and forearms. First, with an artificial sebum mixed with Carbon Black particles, named "sebollution," we evaluated, through an instrumental color measurement, the cleansing efficacy of some shampoo on scalp and hair. The second protocol allowed to assess the interaction between hair care product deposit (shampoo, conditioner, mask, and leave-on) on hair and carbon black particles spread on fiber. The quantification of particle coverage allowed to evaluate the efficiency of a formula to limit the aerial pollution deposit on hair fiber. RESULTS: To simplify and accelerate the evaluation of 42 shampoo formulae, an extrapolation of the scalp cleaning process was validated on forearm. The respective cleanabilities were calculated and covered a large range of efficacy, from 5%, for a basic bland shampoo generally used to reset swatches, to a strong deep cleansing efficacy of 100%. On hair swatches, cleanability efficiencies of five shampoo were also evaluated to eliminate the deposited of sebollution, in a range of 40%-80%. To quantify the efficacy of preventing the deposition of carbon particle on hair surface, the percentage of coverage of 45 different products was measured, from 2% to 16%. The performance depended of the product category (shampoo, conditioner, mask, and leave-on), driven by the performance of the product deposit, and the capacity of this deposit to interact with aerial pollution. CONCLUSION: Three new protocols and evaluation methods are proposed to evaluate and quantify the performance of hair care product, to remove/clean, limit, and protect the hair fibers against the aerial pollution that could interact with hair, scalp and sebum. The validation of these approaches was done through the testing of a large panel of hair care product leading to a complete and sincere evaluation of cleansing and anti-deposit efficacy. Combining the knowledge acquired on pollution impact on hair and the development of specific way of evaluation, this work reinforced the rationale of using and developing new cosmetic products that reduced the impact of pollution upon some hair properties.

Hair transparency decoding in Asia: From stylists' perception to in vitro measurement.

BACKGROUND: The concept of hair transparency has been claimed widely in the Japan (and now it is spreading to Asian) hair color market. Despite the general use of this concept, to date, there is no clear and objective description to accurately explain what it is. In this work, we have decoded and gave clarity to the concept of hair transparency via a technical model (validated for both Japan and China markets) composed of measurable parameters of hair property using a single device. METHODOLOGY AND RESULTS: A comprehensive study composed of various tests was used, starting with a qualitative identification of key parameters via in-depth workshop discussions with over 40 Japanese stylists and a panel of 12 consumers. These identified parameters (luminosity, color visibility, and Shine) were then translated into technically measurable parameters of the hair fiber (Diffused light intensity, ratio of RGB channel intensities of Diffused light, and luster) via a single instrument-Hair SAMBA (a dual-polarized imaging system). Afterward, 10 carefully selected anchor shades were used as visual stimuli in an online pairwise comparison (PC) study with 100 Japanese stylists to generate quantitative transparency perception data of the swatches. Technical parameters of these swatches were measured by SAMBA and consolidated with the PC output, for the creation and validation of the mathematical model. After, with another PC study (N = 100) in China, with seven shades from Japan study and 6 additional Chinese market shades, the applicability of the model in China market was validated. CONCLUSION: We have clarified and quantified the concept of hair transparency through a consumer centric approach and with objective data. Our findings will enable the development of optimum transparent shades which better suits consumer needs. Lastly, we would like to highlight the beauty of digitalization in the study: The digital evaluation pathways chosen allowed us to collect quantitative consumer data from two countries for the creation of a robust model under the impact of COVID-19 and would definitely be the way to go for our future consumer evaluation studies.

Virtual approach of the aesthetical fit between hair colours and skin tones in women of different ethnical origin backgrounds.

OBJECTIVE: To determine the aesthetical accordance between a given skin tone and the 11 possible colours of head hairs, covered by a marketed hair colouration product. MATERIAL AND METHODS: The photographs of professional top models, representing several ancestries (non-Hispanic European and Euro-American, East Asian, Hispanic Euro-American, and African-American ancestries), were used to virtually modify skin tones (from light, medium to dark) and hair colour by an artificial intelligence (AI)-based algorithm. Hence, 117 modified photographs were then assessed by five local panels of about 60 women each (one in China, one in France and three in US). The same questionnaire was given to the panels, written in their own language, asking which and how both skin tones and hair colours fit preferentially (or not appreciated), asking in addition the reasons of their choices, using fixed wordings. RESULTS: Answers from the five panels differed according to origin or cultural aspects, although some agreements were found among both non-Hispanic European and Euro-American groups. The Hispanic American panel in US globally much appreciated darker hair tones (HTs). Two panels (East Asian in China and African American in US) and part of non-Hispanic European panel in France declared appreciating all HTs, almost irrespective with the skin tone (light, medium and dark). This surprising result is very likely caused by gradings (in %) that differ by too low values, making the establishment of a decisive or significant assessment. By nature highly subjective (culturally and/or fashion driven), the assessments should be more viewed as trends, an unavoidable limit of the present virtual approach. The latter offers nevertheless a full respect of ethical rules as such objective could hardly be conducted in vivo: applying 10 or 11 hair colourations on the same individual is an unthinkable option. CONCLUSION: The virtual approach developed in the present study that mixes two major facial coloured phenotypes seems at the crossroad of both genetic backgrounds and the secular desire of a modified appearance. Nonetheless, this methodology could afford, at the individual level in total confidentiality, a great help to subjects exposed to some facial skin disorders or afflictions.

Tribology of an assembly of hairs: Influence of multiscale surface chemistry and structure on sensorial tactile properties.

BACKGROUND: Hair fibers may be either oriented in a common direction or randomly arranged. Fiber arrangement as well as cosmetic treatment control the sensorial perception. The present study explores the respective influence of these two aspects by predicting the product performance in terms of tactile perception. MATERIALS AND METHODS: Friction forces between hair swatches of different curl patterns using a finger-like probe have been measured to better mimic real-life hair/finger contact. Measurements of fiber alignment, hair diameter (thickness), and compression tests were performed on natural and treated swatches to assess the respective weight of these parameters. RESULTS: Conditioned hair exhibit an adhesive behavior measured at the start of the frictional movement. Conversely, natural hair is influenced by fiber reorientation. After a few seconds, friction-related signals stabilize. Thus, the averaged friction forces do not only depend on hair thickness, but increase with a decreased alignment of the fibers. CONCLUSIONS: Intrinsic (diameter/curliness) and external (orientation/ friction/compression) characteristics allow to define a model of "macroscopic" roughness linked to the sensorial characterization. As friction of hair swatches depends upon fiber alignment and coating, this combined approach is potentially a very useful in vitro test, as an alternative or complementary method to sensory tests.

Skin moisture assessment using Hydration Sensor Patches coupled with smartphones via Near Field Communication (NFC). A pilot study with the first generation of patches that allow self-recordings of skin hydration.

OBJECTIVES: To evaluate the potency of a new skin hydration sensor patch in the fast self-recording of skin hydration. MATERIAL AND METHODS: The Skin Hydration Sensor Patch (SHSP) turns the user's smartphone into a wireless skin moisture measuring device. The SHSP combines a capacitive measurement unit and Near Field Communication technology (NFC) for transmitting data and energy. The probe is fixed onto the back of the smartphone and pressed to the skin for a few seconds where the application immediately calculates the capacitance value. Once recorded, the probe is then immediately taken off from the skin. In a first study, this system was compared to the Corneometer® technique, in vivo, on various skin sites of 23 healthy French women. In a second study, 20 women with moderate dry skin on face and forearm self-recorded, through the SHSP the changes in skin hydration induced by a Xanthan gel containing 3% (w/w) of Glycerol, along 24 hours. A questionnaire based on 5 types of questions was established to be filled by subjects about their perception of the use of this new system. RESULTS: In the first study, the values recorded by the SHSP were found highly correlated with those provided by the Corneometer® . The second study allowed to observe significant differences in skin hydration of both sites at all times, as compared to values obtained before the application of the gel. Differences between both sites were observed, the face being less hydrated than forearm. From a practical aspect, the self-recordings on the face show a higher variability (approx. 10% than those of the forearm). The questionnaire led to positive answers on almost all points. CONCLUSION: This SHSP appears as a promising approach in the field of connected skin-related devices. As such, it opens or enlarges a new paradigm in the relationships between a consumer and a cosmetic product.

Quantifying the impact of braiding and combing on the integrity of natural African hair.

BACKGROUND: Afro hair breakage is most commonly attributed to grooming practices such as braiding, hair extensions and weaves, both for chemically treated hair and natural Afro hair. These grooming practices are also frequently associated with traction alopecia in clinical studies. However, there is little to no quantitative scientific data on the surface and internal hair fibre damage caused by grooming, including combing, on Afro hair. METHODS: Qualitative and quantitative techniques such as scanning electron microscopy, cuticle cohesion and tensile testing were used to determine the effects of frequent braiding on the integrity of female Afro hair in 15 frequent braiders and 15 occasional braiders (control group) in Johannesburg, South Africa. Frequent braiders were women who braided more than 8 times per year, while occasional braiders typically limit braiding to only twice 2 per year. The severity of traction alopecia was quantified in both groups using the standard Marginal Traction Alopecia Scoring system. Surface damage on naturally curly Afro hair, that was combed but not braided, was assessed as another hairstyle option. RESULTS: All measurements showed a relationship between surface and internal hair fibre damage and braiding frequency. Frequent braiders had thinner hair, with more cuticle damage as shown by SEM and cuticle cohesion assessments. Their hair fibres were also significantly weaker (p < 0.05), as shown by the tensile testing. In addition, they also had higher traction alopecia severity scores. In the combing impact assessment, a linear trend was observed between surface hair fibre damage and the number of combing strokes. Cuticle damage from 480 combing strokes was more severe than that from frequent braiding. CONCLUSION: Frequent braiding and combing damage natural Afro hair. Quantification of damage caused by different grooming practices identifies a need to develop products that could help mitigate specific hair damage associated with grooming practices. The degree of damage and subsequent hair loss could also be minimized by education on best braiding practices to protect the hair fibre and avoid hair follicle miniaturization caused by high traction hairstyles.

CONTEXTE: La casse des cheveux d'origine Africaine est le plus souvent associées à des pratiques cosmétiques telles que le tressage et les extensions de cheveux, à la fois pour les cheveux traités chimiquement et les cheveux naturels. Ces pratiques cosmétiques sont également fréquemment associées à une alopécie de traction, comme le relatent les études cliniques. Cependant, il existe peu ou pas de données scientifiques quantitatives sur l'impact de ce type de pratiques, y compris le peignage, sur les dommages internes et de surface des cheveux d'origine africaine. MÉTHODES: Des techniques qualitatives et quantitatives, comme la microscopie électronique à balayage (MEB), la cohésion cuticulaire et des tests de traction, ont été utilisés pour déterminer les effets du tressage sur l'intégrité des cheveux de deux groupes de 15 femmes Africaines (à Johannesburg, Afrique du Sud) : un premier groupe de femmes pratiquant un tressage fréquent et un autre groupe un tressage occasionnel. Le groupe des tresseurs fréquents correspond à des femmes qui pratiquent le tressage plus de 8 fois par an, tandis que les tresseurs occasionnels limitent généralement le tressage à seulement deux fois par an. La gravité de l'alopécie de traction a été également quantifiée dans les deux groupes à l'aide du système standard de notation de l'alopécie tractionnelle. Parallèlement, à titre de comparaison, les dommages de surface ont été également évalués sur des cheveux d'origine Africaine naturellement bouclés, non tressés, mais qui ont subi un peignage répété. RÉSULTATS: Toutes les mesures ont montré une relation entre les dommages de surface et internes de la fibre et la fréquence de tressage. Les tresseurs fréquents ont des cheveux plus fins, avec un endommagement plus important de la cuticule, comme le montrent les évaluations MEB et la cohésion cuticulaire. Les cheveux sont également significativement plus fragiles (p <0,05), comme le montrent les tests de traction. De plus, ces femmes ont également des scores d'alopécie de traction plus élevés. Dans le cas spécifique du peignage répété, une tendance linéaire a été observée entre les dommages en surface de la fibre capillaire et le nombre de coups de peigne. On peut également noter que l'endommagement de la cuticule causé par 480 coups de peigne est plus important que celui causé par des tressages fréquents. CONCLUSION: Les tressages et peignages fréquents endommagent les cheveux naturels d'origine Africaine. La quantification des dommages causés par différentes pratiques cosmétiques met en évidence le besoin de développer des produits qui pourraient aider à atténuer les dommages liés à des pratiques spécifiques. Le niveau de dommage et la perte de cheveux pourraient également être minimisés par un apprentissage de meilleures pratiques de tressage pour protéger la fibre et éviter la diminution des follicules pileux causée par des coiffures qui entrainent un forte traction sur la fibre.