‘Smooth hair’ or ‘silky hair’ are key claims for many hair products, including shampoos and conditioners.  Furthermore, restoration of hair smoothness is an important signal to consumers that hair damage has been repaired.  As a result, hair friction experiments are widely used for performance testing of conditioning systems, and for supporting damage repair claims.

The dry surface friction test simulates the forces required to rub one’s fingers over the surface of the hair after it has been washed and dried.  It is, therefore, designed to relate directly to the perception of hair smoothness or silkiness, or, alternatively, the lack of hair dryness.  This is different to the ease-of-combing tests that assess the forces required to untangle hair with a brush or comb.

The TRI dry surface friction test measures the force required to pull a tress of hair through two rubber cylinders pressed together, simulating the ends of your fingers.  Careful control of the speed at which the hair is pulled through, the pressure between the cylinders and the environmental conditions (room temperature and humidity), allow discrimination between different conditioning products and measurement of damage repair effects.

Hair friction studies, like hair combing studies, are sensitive to the levels of curl and underlying hair damage and are therefore prone to high levels of variability.  TRI can advise on the best protocols for your study.