Substantiating product claims: COSSMA

Evaluation | The demands on hair care are high. Increasingly critical customers also want the promised benefits to be verifiable. Anne Charpentier presents the various methods of testing products for their effectiveness in terms of protection and care.

Hair is a big part of male or female identity worldwide and, culturally, some importance is being given to the look and style of their hair. Moreover, consumers are seeking new ideas for bettering their hair grooming rituals, in the form of products that are at once inclusive, natural, ethical, and sustainable but maintain their cleansing and caring benefits.

The health treatment of the scalp and the hair forms an integral part of many people’s daily beauty routine. The three main objectives of this regimen are mainly to:

Maintain the good condition of the unique scalp-hair ecosystem considering the internal triggers (stress, diet…): Exfoliation, moisture, sebum, sweat, microbiota (Malassezia), acidic pH, etc.
Cure and protect it from external aggressions such as UV, heat, and various pollution.
Make the hair more attractive and change its style and appearance.

Long list of performances

Consumers expect a multitude of benefits for use regardless of the type and ethnicity of their hair: care, volume, anti-frizz, smoothing, flat hair, repair, gloss, shine, colour, fine hair, curly hair, straightening effect, restore, anti-sebum, anti-dandruff, UV protection, anti-breakage, moisturising etc.

Clinical tests, use tests and biometrological studies in vivo or on hair strands play a key role in research and development for hair and scalp grooming to evaluate their efficacy and safety and improve hair care beauty products or scalp treatments to market. Finding the relevant method and the experienced testing partner, and designing the reliable protocol is the ordinary challenge of main evaluation managers and cosmetic chemists.

Biometrological measurements

The various biometrological protocols dedicated to fibres, strands and hair testing are focusing different targets: the scalp, the cuticle, the cortex, the hair structure and mechanisms or the growth and can be implemented under controlled conditions of temperature, hygrometry, and humidity¹.

The good practices for haircare product assessments are based on a panel adapted to the product claims, using clinical scoring, self-evaluation, instrumental measurements, samples for analysis (scanning electron microscopy, micro-biota, etc.), and illustrative pictures. It represents a complete approach of hair care performance.

As a complementary point of view, other protocols including the scorage by dermatologists or hairdressers, the insight of consumers via questionnaire of lifestyles, the sensory analysis and emotions studies are highly recommended.

Various devices help to measure the effects of the product on the hair and scalp.

Physical and mechanical properties:

Fibre aspects and swelling analysis: hair cross-section by dimensional analysis.

Mechanical properties analysis (Young’s modulus, extension to breakage, Stress to break)². This technique evaluates the impact of hair treatments on the mechanical characteristics of the treated fibres.

Combing and abrasion of the hair³.

Volume, straightness, and anti-frizz effect: 3D reconstruction⁴, that allows to take pictures of a strand of hair that rotates on itself in front of a light background, then to convert them into grayscale. It analyses them by thresholding to differentiate the body of the strands and frizz. Hair orientation is also made⁵.

Testing laboratories implement hair locks testing in a controlled temperature and hygrometry environment on standardised hair tresses adapting to different types of hair (Caucasian, Asian, Brazilian, African hair, straight hair, wavy or curly, etc.).

Treatments can be performed before the product application to weaken hair to evaluate its efficacy on sensitised fibre. Moreover, evaluation involving real life sun exposure, real-life sea exposure, swimming-pool exposure, or even real-life sports activities to better support pioneering cosmetic claims.

Chemical properties:

Colour and brightness and permeation, colour fade, bleaching test using various devices⁶.
Hair permeability: infra-red microscopy, confocal microscopy, scanning electron microscopy, optical multiphoton tomography, atomic force microscopy etc.

To study the scalp, most of the instrumentation used are coming from the skin analysis field with some adaptations considering the surface topology and the size of the studied area. Most of these tests are implemented in vivo on men or women scalp with the quantification and visualisation of the searched effects⁷.

These tests are carried out with appropriate devices:

Moisturising⁸
Barrier Function⁹
Soothing¹⁰
Anti-sebum¹¹
Anti-Dandruff by gravimetry and imaging¹²
Scalp surface¹³
Hair loss and hair growth and density¹⁴.
Microbiome of the scalp: Propionibacterium acnes, Staphylococcus epidermidis, Malassezia. Metagenomic analysis such as 16s ribosomal gene sequencing¹⁵.
Hair protection: against temperature, radiation, chemicals, odour, or anti-pollution assessment. With anti-pollution end points such as Malondialdehyde (MDA), free fatty acids, the melanin and protein content, and Tryptophan degradation. Or pH-meter measures, or the measurement of transepidermal water loss¹⁶.

Finally, among the different test of biodegradability and ecotoxicology that are more and more asked by the consumers, a new trend following the necessity of eco responsibility is the test of water quantity reduction during the product rinsing developed for both solid and liquid products.

What is the future?

The new digital era undoubtedly influences the beauty lifestyle and the personalisation of the hair care experience. It is propelling hair salons into the digital age using hair diagnostics and augmented  reality solutions. It gives the opportunity, to analyse the fibre and scalp, make a diagnosis and personalise hair care treatment on-site based on a client’s hair data.

References:

¹ Bossa Nova Humidity Chamber

² Micro-Tensile Tester MTT675 extensometer coupled to the Fiber Dimensional Analysis Unit (FDAS) of Dia-Stron

³ Friba.one, Sirtaki (Bossa Nova), Fibrestress. Micro-Tensile Tester MTT175 (Dia-Ston) extensometer

⁴ with of a Bolero (Bossa Nova)

⁵ with the Rumba (Bossa Nova)

⁶ Goniolux1 (Orion), GlossyMeter (Courage + Khazaka), SkinColorCatch & SkinGlossMeter, Samba Hair, Mambo, Salsa and Brightness index using the Samba Hair (Bossa Nova), SkinCam & SpectraCam (Newtone), C-Cube CR (Pixience)

⁷ These information are bundled on the clinical testing platform:

⁸MoistureMap & Corneometer(Courage + Khazaka, Dermalab Hydration, Aquaflux & Epsilon (Biox), MoistureMeter SC, MoistureMeterEpi, MoistureMeterD, C-Cube (Pixience)

⁹ Vapomerter, Aquaflux (Biox), etc.

¹⁰ Tivi 700 and Tivi 8000 (Wheesbridge), Thermographie infrarred, Neurometer, C-Cube (Pixience) etc.

¹¹ QuantiSeb, DermaLab Sebum, Sebumeter (Courage + Khazaka), SebumScale including sebum analysis: Shotgun mass spectrometry, Metabolimic MS/MS-16srDNA-PCR (Phylogene), Raman microscopy, ATR-FTIR spectroscopy (Newtone) etc.

¹² DandruffMeter (Courage + Khazaka), C-Cube (Pixience) etc.

¹³ VisioScan (Courage +Khazaka), Antera 3D (Miravex), C-Cube (Pixience), Skin Damage Vizualizer and all dermoscopes etc.

¹⁴ phototrichogram, C-Cube (Pixience), Trichoscan, SkinCam (Newtone)

¹⁵ Phylogene

¹⁶ Tewameter Nano (Courage + Khazaka)