Hairstyling from a tribology point of view
In everyday life people use hairstyling products such as waxes or gels, to improve the holding of hair and improve/change its appearance. However, in the market there are many products available, claiming to have different characteristics (e.g. strong hold, silky/smooth touch…). To define the performance of such products, tribology comes into play. In particular two parameters are important. The friction determines how easy a wax or gel can be applied, whereas the stickiness and tackiness determine their holding ability.
For this application case the updated Basalt-N2 was used, operated at the mN range. In particular, two different test procedures are developed to evaluate the friction and stickiness/tackiness of commercial waxes and gels. To investigate the frictional behavior, a scratch test was performed on a thin film of wax or gel on a metallic substrate. The counter material was a silicone disk that simulates the area contact between the finger skin and the hairstyling media. Different sliding speeds, applied loads and sliding distances can be used to evaluate and compare different contact conditions. The stickiness/tackiness of waxes or gels was measured based on approach-retraction curves. In this procedure a silicone counter body gradually approaches the thin film of wax or gel, until a pre-set contact load is reached. Then, the silicone moves away from the greased substrate under well controlled conditions, 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.
- Both the friction and stickiness of gels and waxes can be measured by the Basalt-N2. This dual approach can be used to provide a ranking on the stickiness behaviour of commercial hairstyling products.
- Wax appears to stick more than gel : higher pull-off force. But its stickiness decreases sharply after the first cycle.
- Gels have a lower friction than waxes. The coefficient increase during sliding as the gel piles around the silicone counter material.