For product treatments that are designed to thicken the hair fibre, the Dia-Stron FDAS770, a high-resolution laser micrometer, can be used to capture the maximum and minimum fibre dimensions at multiple points along a sample length. Comparing to before treatment or to a control group enables a change in fibre dimensions to be calculated to support ‘increase in thickness related claims.
Hair fibres swell when immersed in water. Damaged hair swells to a greater extent and at a different rate than undamaged hair. Using the Dia-Stron DSM770 dynamic swelling module, the in-situ diameter of single hair fibres can be measured.
Wet swelling measurements can be used to quantify hair damage, the effect of treatment in preventing/ ‘repairing’ damage, as well as a parameter for hair porosity evaluation.1
1 Gasparin RM, Lourenço CB, Leonardi GR. Porosity and resistance of textured hair: Assessing chemical and physical damage under consumer relevant conditions. Cosmetics, 2025; 12(3): 93