Читать книгу Surface Science and Adhesion in Cosmetics - Группа авторов - Страница 54

The deposition of simple lipstick containing PE wax and single oils is evaluated as described in the experimental section. The effect of viscosity from selective oils on the lipstick deposit and lipstick hardness is shown in Figure 2.24. It is observed that increasing oil viscosity increases lipstick hardness but decreases the deposit thickness of lipstick on Bioskin. The results obtained are opposite to those for the wax – oil systems containing synthetic wax - polyethylene - polypropylene/ethylene copolymer reported in [33]. In that study, increasing oil viscosity enhanced the hardness of the lipstick and more deposit of lipstick was observed.

The deposit of applied lipstick is also dependent on wax amount and wax type. With low wax amount, the lipstick is softer and thickness of deposit is higher. De Clermond-Gallerande et al. [33] also observed that the thickness, smoother texture and uniformity of applied lipstick were enhanced when low amount of wax was used. In addition, at a fixed wax amount, changing wax type will change the thickness of applied lipstick.

Table 2.8 Effect of wax amount on lipstick hardness and structure in selected polar oils.

Figure 2.24 Effect of the thickness of deposit on lipstick hardness on Bioskin.

Figure 2.25 Effect of oil polarity and oil viscosity on sensorial perception (S+M region is the transition between smooth (S) and moist (M) regions).

The sensorial perception of more than 70 simple lipsticks containing oils with various polarities and viscosities was evaluated by professional formulators. The results show that the sensorial perception is strongly dependent on oil viscosity, but neither on oil polarity nor on hardness of lipstick (Figure 2.25) which is consistent with the conclusions from Abidh and coworkers [34]. When viscosity increases, the sensorial perception changes from being smooth to moist and then sticky. The transition between smooth and moist regions gives a watery feeling that is favored by Japanese consumers.