Methods adapted to evaluate products for textured hair: Shine, curl shrinkage, flexibility and consumer‐perceived hair porosity

Objective This work presents adapted methods for quantifying hair shine, shrinkage, flexibility and consumer‐perceived porosity in textured hair. Methods The shine evaluation method utilizes image analysis of standardized hair tresses under controlled lighting conditions. A custom‐built imaging chamber minimizes extraneous light, while a macro written for ImageJ isolates and quantifies shine points based on grayscale thresholding. Additionally, hair greying caused by sebum or product application is evaluated by analysing the darkest and brightest pixels. Curl shrinkage profiles are assessed using imaging and image analysis techniques, allowing hair length changes to be evaluated as a function of humidity, product application and time. A three‐point bending technique was adapted to assess curl stiffness or flexibility in type 4 hair products. Contact angle measurement was refined to measure consumer‐perceived hair porosity. This included designing an adapter to securely fix textured hair during testing and recording video frames for improved measurement precision. Results Shine evaluation method: The region of interest ROI and shine evaluation parameters less sensitive to curl pattern were proposed. Hair greying was found to depend largely on the loss of bright colour during light reflection. Effective shine treatments not only improved shine but also restored hair colour vibrancy by enhancing the darkest and brightest shades. Curl shrinkage test method: Testing was standardized at 30% and 60% relative humidity. For type 3 hair, an appropriate test duration at 60% humidity was 6 h, while for type 4 hair, it was 8 h. Reduced hair tress mass (e.g. 0.25 g) minimized length evaluation challenges in type 4 hair and type 3 tresses. Three‐point bending technique: Despite excellent curl shrinkage management properties, certain fixative products (e.g. gels) significantly increased hair stiffness, while others of similar efficacy maintained flexibility comparable with virgin hair. Contact angle method adaptation: Consumer‐perceived surface porosity was evaluated in differently treated type 4 hair. Repeated heat damage did not alter this parameter. Oxidized hair exhibited similarly low surface hydrophobicity, which was lower than that of relaxer‐treated hair. Conclusions The methods discussed demonstrate their suitability for evaluating the ability of products to influence textured hair shine, shrinkage management, flexibility and consumer‐perceived porosity.