Skin creams are commonly used to improve skin health and create a smooth, soft, and moist perception. This is achieved by altering the surface roughness, friction, and adhesion of skin surface. Despite the fact that there are many commercial creams available, there is no consistent scientific approach to determine their frictional and adhesive properties.
Two different test procedures are used on the Basalt-N2 tribometer for friction and adhesion of commercial skin creams. Friction is studied by a reciprocating sliding, performed by applying a film of cream on an artificial skin. As a counter material, silicone was used to simulate the mechanical properties of skin. Different sliding speeds, applied loads and sliding distances can be used to evaluate and compare different ways of cream application and sensation. In addition, the adhesion of the skin creams was measured based on approach-retraction curves. In this procedure a silicone counter body gradually approaches the artificial skin with the cream, until a pre-set contact load is reached. Then, the silicone moves away from the substrate, until complete physical separation is achieved. During this approach-retraction cycle, the force on the load sensor is measured as a function of time and distance moved.
- The frictional behavior of various creams can be compared in an accurate, objective and economically efficient way, under realistic conditions.
- The same apparatus and setup can also be used to measure the adhesion and separation energy of creams on artificial skin.